P.1 

OAR Box 1392 

Prepped by Ollie Stewart 

Document Number: 

127) ll-A-2 

Docket Number: 

A-94-52 

Printed 7/7/2008 9:45:58 AM Sheet 127 oj136 
LOCATING AND ESTIMATING 

AIR#ilSSIpNS FROM SOURCES 

OF STYRENE, INTERIM REPORT 

P.2 

%'frt 

United Statfc 

Environmental Protection 

Agenq 

Office of Air Quality 

Planning And Standards 

Research Triangle Park; NC 27711 

EPA-450/4-91-029 

Octoberl991 

AIR 

ME; \ N 1 r^ ti \ 
P 3 

EPA-450/4-91-029 

October 1991 

LOCATING AND ESTIMATING AIR EMISSIONS 

FROM SOURCES OF STYRENE, 

INTERIM REPORT 

By 

Darcy Campbell 

Radian Corporation 

Research Triangle Park, North Carolina 

Contract Number 68-DO-0125 

EPA Project Officer: Anne A. Pope 

U. S. ENVIRONMENTAL PROTECTION AGENCY 

Office Of Air and Radiation 

Office Of Air Quality Planning And Standards 

Research Triangle Park, North Carolina 27711 

or-j-
P.4 

This report has been reviewed by the Office of Air Quality Planning 

and Standards, U. S. Environmental Protection Agency, and has been 

approved for publication. Mention of trade names or commercial 

products does not constitute endorsement or recommendation for use. 

EPA 450/4-91-029 

n 
P.5 

PREFACE 

This version of the "Locating and Estimating Air Emissions 

from Sources of Styrene" is being published as an Interim Report 

pending incorporation of testing results from the U.S. 

Environmental Protection Agency (EPA). The EPA is currently 

testing several unsaturated polyester resin fabricators who 

produce cultured marble bathroom fixtures. When the test results 

are available, the EPA will, publish a final report including this 

data. Until that time, however, all of the information contained 

in this document is available to Federal, State, and local air 

pollution personnel who are interested in locating other 

potential sources of styrene and estimating air emissions. 

111 

i • imjm n*B!**!m*J 
P.6 

TABLE OF CONTENTS 

Section Page 

PREFACE iii 

1 Purpose of Document 1 

References for Section 1 4 

2 Overview of Document Contents 5 

3 Background 7 

Nature of Pollutant 7 

Overview of Production and Use 9 

References for Section 3 20 

4 Emissions from Styrene Production 23 

Process Description 23 

Emissions 32 

References for Section 4 . 41 

5 Emissions from Major Uses of Styrene 43 

Polystyrene Production 43 

Styrene-Butadiene Copolymer Production 54 

Styrene-Acrylonitrile Production 65 

Acrylonitrile-Butadiene-Styrene Copolymer 

Production 73 

Unsaturated Polyester Resin Production 82 

Miscellaneous Styrene Copolymer Production ... . 91 

References for Section 5 . 94 

6 Emissions from the Use of Styrene-Containing Materials . 97 

Thermodegradation of Styrene-Containing Materials . 99 

Acrylonitrile-Butadiene-Styrene Compounding ... . 101 

Unsaturated Polyester Resin Use 109 
" " l 

TABLE OF CONTENTS (Continued) 

Section Page 

Polystyrene Foam . .. 129 

References for Section 6 140 

7 Source Test Procedures 143 

EPA Reference Method 18 143 

NIOSH Method 1501 . 145 

EPA Method 5040 146 

Compendium Method TO-14 147 

EPA Reference Method 8270 149 

References for Section 7 ..-.-. 150 

A 

vi 
P.8 

LIST OF TABLES 

Table Page 

1 Chemical and Physical Properties of Styrene 8 

2 End-Uses of Styrene 12 

3 Potential Source Categories of Styrene Emissions ... . 13 

4 Styrene Production Locations and Capacities 24 

5 Styrene Storage and Secondary Emission Factors 34 

6 Average Emission Factors for Fugitive Emissions ... . 36 

7 Control Techniques and Efficiencies Applicable to 

Equipment Leak Emissions 38 

8 Polystyrene Production Facilities . . 45 

9 Emission Factors for Polystyrene Production 55 

10 Styrene-Butadiene Elastomer Production Facilities .. . 57 

11 Styrene-Butadiene Latex Production Facilities 58 

12 Typical Recipe for Emulsion SBR 61 

13 Emission Factors for Styrene-Butadiene Production .. . 66 

14 Styrene-Acrylonitrile Production Facilities ..... . 67 

15 Acrylonitrile-Butadiene-Styrene Production 

Facilities 75 

16 Typical Components Used to Form Unsaturated 

Polyester Resins 83 

17 Producers of Unsaturated Polyester Resins 86 

18 Emission Factors for Styrene from UPR Production ... . 90 

19 Miscellaneous Uses for Styrene in Chemical Production . 92 

20 Prevalence of Styrenic Resin Fabricators 98 

21 Styrene Emitted from Thermobxidative Degradation ... . 100 

22 Summary of Source Testing Data for an ABS Compound 

Facility Uncontrolled and with Temporary Controls . . . 105 

23 Summary of ABS Compounding Facility Source Test 

Data After Installation of Permanent Controls ... . 108 

v n 
1 

LIST OF TABLES (Continued) 

Table Page 

24 Geographic Distribution of Fiberglass Boat Industry 

by Number of Facilities . 119 

25 VOC Emission Factors for Polyester Resin Product 

Fabrication Processes .. . 124 

26 Monomer-Based Emission Factors for Polyester 

Resin/Fiberglass Operations 125 

27 Factors Affecting Styrene Emissions from Lamination . . 128 

28 Domestic Consumption of Polystyrene Foam by End Uses . . 131 

29 Distribution of PSF Producers by State 132 

Vill 
P.10 

LIST OF FIGURES 

Figure Page 

1 Chemical Use Tree for Styrene 11 

2 Locations of Plants Manufacturing Styrene 25 

3 Process Flow Diagram for Styrene Production by 

Ethylbenzene Dehydrogenation 27 

4 Process Flow Diagram for Styrene Production by 

Ethylbenzene Hydroperoxidation . . 29 

5 Process Flow Diagram for Styrene Production by 

Isothermal Processing 31 

6 Polystyrene Production by Suspension Polymerization . . 49 

7 Polystyrene Production by Mass Polymerization 50 

8 Polystyrene Production by Solution Polymerization .. . 52 

9 S-B/SBR Production by Emulsion Polymerization 59 

10 SBR Production by Solution Polymerization . 63 

11 Production of SAN by Emulsion Polymerization 69 

12 Production of SAN by Suspension Polymerization 71 

13 Production of SAN by Continuous Mass Polymerization . . 72 

14 Production of ABS/SAN by Emulsion Polymerization ... . 77 

15 Production of ABS by Suspension Polymerization 79 

16 Production of ABS by Continuous Mass Polymerization . . 81 

17 Typical Reactions for Unsaturated Polyester and 

Polyester Resin Formation . . 85 

18 Unsaturated Polyester Resin Production 89 

19 Original Vacuum and Vent System at an ABS 

Compounding Facility 102 

20 Permanent VOC Controls at an ABS Compounding Facility . 107 

21 Typical Filament Winding Process 113 

22 Typical Continuous Lamination Production Process ... . 115 

23 Geographic Distribution of Fiberglass Boat Manufacturing 

Facilities for States with More than Ten Facilities . . 121 

IX 
P.11 

LIST OF FIGURES (Continued) 

Figure Page 

24 Fiberglass Boat Production Process . 122 

25 Flow Diagram of Typical Polystyrene Foam Sheet 

Manufacturing Process . . 133 

26 Flow Diagram of a Typical Polystyrene Foam Board 

Manufacturing Process 136 

27 Flow Diagram of a Typical EPS Bead Process . . • 137 

28 Integrated Bag Sampling Train 144 

29 Schematic Diagram of Trap Desorption/Analysis System . . 147 

x 
P.12 

SECTION 1 

PURPOSE OF DOCUMENT 

The Environmental Protection Agency (EPA) and State and 

local air pollution control agencies are becoming increasingly 

aware of the presence of substances in the ambient air that may 

be toxic at certain concentrations. This awareness, in turn, has 

led to attempts to identify source/receptor relationships for 

these substances and to develop control programs to regulate 

emissions. Unfortunately, very little information is available 

on the ambient air concentrations of these substances or on the 

sources that may be discharging them to the atmosphere. 

To assist groups interested in inventorying air emissions of 

various potentially toxic substances, EPA is preparing a series 

of documents such as this that compiles available information on 

sources and emissions of these substances. Prior documents in 

the series are listed below: 

Substance EPA Publication Number 

Acrylonitrile 

Carbon Tetrachloride 

Chloroform 

Ethylene Dichloride 

Formaldehyde (Revised) 

Nickel 

Chromium 

Manganese 

Phosgene 

Epichlorohydrin 

Vinyl Chloride 

Ethylene Oxide 

Chlorobenzenes 

Polychlorinated Biphenyls (PCBs) 

« 

Polycyclic Organic Matter (POM) 

Benzene 

Organic Liquid Storage Tanks 

Coal and Oil Combustion Sources 

Municipal Waste Combustors 

Perchloroethylene and Trichloroethylene 

EPA-450/4-84-007a 

EPA-450/4-84-007b 

EPA-450/4-84-007C 

EPA-450/4-84-007d 

EPA-450/2-91-012 

EPA-450/4-84-007f 

EPA-450/4-84-007g 

EPA-450/4-84-007h 

EPA-450/4-84-007i 

EPA-450/4-84-007J 

EPA-450/4-84-007k 

EPA-450/4-84-0071 

EPA-450/4-84-007m 

EPA-450/4-84-007n 

EPA-450/4-84-007p 

EPA-450/4-84-007q 

EPA-450/4-88-004 

EPA-450/2-89-001 

EPA-450/2-89-006 

EPA-450/2-90-013 
_EJi 

1,3-Butadiene 

Chromium (supplement) 

Sewage Sludge 

EPA-450/2-89-021 

EPA-450/2-89-002 

EPA-450/2-90-009 

This document deals specifically with styrene. Its intended 

audience includes Federal, State and local air pollution 

personnel and others who are interested in locating potential 

emitters of styrene, and making gross estimates of air emissions 

therefrom. 

Because of the limited amounts of data available on some 

potential sources bf styrene emissions, and since the 

configurations of many sources will not be the same as those 

described here, this document is best used as a primer to inform 

air pollution personnel about (1) the types of sources "that may 

emit styrene, (2) process variations and release points that may 

be expected within these sources, and (3) available emissions 

information indicating the potential for styrene to be released 

into the air from each operation. 

The reader is strongly cautioned against using the emissions 

information contained in this document to try to develop an exact 

assessment of emissions from any particular facility. Because 

insufficient data are available to develop statistical estimates 

of the accuracy of these emission factors, no estimate can be 

made of the error that could result when these factors are used 

to calculate emissions from any given facility. It is possible, 

in some extreme cases, that order-of-magnitude differences could 

result between actual and calculated emissions, depending on 

differences in source configurations, control equipment, and 

operating practices. Thus, in situations where an accurate 

assessment of styrene emissions is necessary, source-specific 

information should be obtained to confirm the existence of 

particular emitting operations, the types and effectiveness of 

control measures, and the impact of operating practices. A 

source test and/or material balance should be considered as the 

best means to determine air emissions directly from an operation. 

In addition to the information presented in this document, 

another potential source of emissions data for styrene is the 

Toxic Chemical Release Inventory (TRI) form required by Section 

IWflSWUiWW *W * 
P.14 

313 of Title III of the Superfund Amendments and Reauthorization 

Act of 1986 (SARA 313).x SARA 313 requires owners and operators 

of certain facilities that manufacture, import, process or 

otherwise use certain toxic chemicals to report annually their 

releases of these chemicals to any environmental media. As part 

of SARA 313, EPA provides public access to the annual emissions 

data. The TRI data include general facility information, 

chemical information, and emissions data. Air emissions data are 

reported as total facility release estimates, broken out into 

fugitive and point components. No individual process or stack 

data are provided to EPA. The TRI requires the use of available 

stack monitoring or measurement of emissions to comply with SARA 

313. If monitoring data are unavailable, emissions are to be 

quantified based on best estimates of releases to the 

environment. 

The reader is cautioned that the TRI will not likely provide 

facility, emissions, and chemical release data sufficient for 

conducting detailed exposure modeling and risk assessment. In 

many cases, the TRI data are based on annual estimates of 

emissions (i.e., on emission factors, material balances, 

engineering judgment). The reader is urged to obtain TRI data in 

addition to information provided in this document to locate 

potential emitters of styrene, and to make preliminary estimates 

of air emissions from these facilities. To obtain an exact 

assessment of air emissions from processes at a specific 

facility, source tests or detailed material balance calculations 

should be conducted, and detailed plant site information should 

be compiled. 
P.15 

REFERENCES FOR SECTION 1 

ase Reporting: 

•21208. June 4, 1987. 

1. Toxic Chemical Release Reporting: Community Right-To-Know. 

Federal Register 52(107): 21152-21208. .Tnno A iaai 
P.16 

SECTION 2 

OVERVIEW OF DOCUMENT CONTENTS 

As noted in Section 1, the purpose of this document is to 

assist Federal, State and local air pollution agencies and others 

who are interested in locating potential air emitters of styrene 

and making gross estimates of air emissions therefrom. Because 

of the limited background data available, the information 

summarized in this document does not and should not be assumed to 

represent the source configuration or emissions associated with 

any particular facility. 

This section provides an overview of the contents of this 

document. It briefly outlines the nature, extent, and format of 

the material presented in the remaining sections of this report. 

.. Section 3 of this document briefly summarizes the physical 

and chemical characteristics of styrene, and provides an overview 

of its production and use. This background section may be useful 

to someone who needs to develop a general perspective on the 

nature of this substance and how it is manufactured and consumed. 

Sections 4, 5, and 6 of this document focus on major source 

categories that may discharge styrene air emissions. Section 4 

discusses emissions from the production of styrene; Section 5 

discusses emissions from the major uses of styrene; and Section 6 

addresses emissions from the use of styrene-containing materials. 

For each major industrial source category described in 

Sections 4, 5, and 6, example process descriptions and flow 

diagrams are given, potential emission points are identified, arid 

available emission factor estimates are presented.-that., show the 

potential for styrene emissions before and after..controls are 

employed by industry. Individual companies are named that are 

reported to be involved with either the production or use of 

styrene based primarily on information from trade publications. 

The final section of this document summarizes available 

procedures for source sampling and analysis of styrene. Details 

are not prescribed nor is any EPA endorsement given or implied to 
z 

any of these sampling and analysis procedures. At this time, EPA 

has not generally evaluated these methods. Consequently, this 

document merely provides an overview of applicable source 

sampling procedures, citing references for those interested in 

conducting source tests. 

This document does not contain any discussion of health or 

other environmental effects of styrene, nor does it include any 

discussion of ambient air levels or ambient air monitoring 

techniques. 

Comments on the contents or usefulness of this document are 

welcomed, as is any information on process descriptions, 

operating practices, control measures and emissions information 

that would enable EPA to improve its contents. All comments 

should be sent to: 

Chief, Emission Factor and Methodologies Section 

Emission Inventory Branch (MD-14) 

U. S. Environmental Protection Agency 

Research Triangle Park, North Carolina 27711 
P.18 

SECTION 3 

BACKGROUND 

NATURE OF POLLUTANT 

Styrene (CAS No. 100-42-5) is an unsaturated aromatic 

monomer that is widely used in the production of plastics, 

resins, and elastomers. In the past century production and use 

of styrene have increased rapidly because it can be polymerized 

and copolymerized easily to produce a wide variety of products. 

Styrene was the twenty-first highest-volume chemical produced in 

the United States in 1988.1 

Styrene's molecular formula is represented as: 

CH-CJ^ 

Table 1 shows the chemical and physical properties of 

styrene. Because of styrene's flammability and its ease of 

polymerization, an inhibitor (10-15 ppm tert-butylcatechol) must 

be added during storage and high temperatures must be avoided.3 

Styrene is released to the atmosphere during its manufacture 

and from the use of styrene-containing materials. Styrene has 

also been detected in small amounts in automobile emissions3 and 

from publicly owned treatment works.4 The combustion of styrenebased products is another potential source of styrene emissions.8 

Styrene is very reactive in the air, reacting readily with 

hydroxyl radicals and ozone.6 Styrene readily undergoes 

oxidation by ozone to produce formaldehyde, benzaldehyde, benzoic 

acid, and traces of formic acid. The styrene half-life resulting 
TABLE 1. CHEMICAL AND PHYSICAL PROPERTIES OF STYRENE 

P.19 

Synonyms: 

Chemical Abstracts 

Registry Number: 

Molecular Formula: 

Molecular Weight: 

Ambient state: 

Boiling Point: 

(760 mm Hg) 

Freezing Point: 

Density: 

Solubility: 

Flammable (explosive) 

Limits: 

Flashpoint: 

Autoignition Temperature: 

Vapor Pressure: 

Concentration in 

Saturated Air: 

Odor Threshold: 

Conversion Factors: 

(25°C, 760 mm Hg) 

Cinnamene, cinnamenol, cinnamol, 

ethenylbenzene, monotryrene, 

phenthylene, phenlethene, 

phylethylene, styrole, styrolene, 

styron, styropol, styropor, 

vinylbenzene, vinylbenzol 

100-42-5 

C6H5CH=CH2 

104.16 

Colorless volatile liquid 

145.2°C (293.4"F) 

-30.6° C (-23.1'F ) 

0.901 8 g/cm3 (25°C) 

Soluble in ethyl ether, benzene, 

methanol, toluene, ethanol, 

acetone, n-heptane, carbon 

tetrachloride, carbon disulfide; 

slightly soluble in water (about 

25 mg/100 g water at 25°C) 

1.1-6.1% by volume in air 

34.4°C (94°F) Tag closed cup 

36.7°C (98*F) Tag open cup 

490°C (914°F) 

:z 

50 

68 

77 

86 

104 

CC) 

(10) 

(20) 

(25) 

(30) 

(40) 

mm Hg 

2.34 

4.50 

6.45 

8.21 

14.30 

fkPa) 

(0.31) 

(0.60) 

(0.86) 

(1.09) 

(1.91) 

8,500 ppm (25*C) 

0.05 - 0.15 ppm 

1 ppm =4.2 6 mg/m3 

1 mg/m3 = 0.235 ppm 

Source: References 7 and 8. 
P.20 

from its oxidation by ozone is estimated to be at least 9 hours.6 

The oxidation of hydroxyl radicals yields benzaldehyde. The 

estimated half-life of styrene from this oxidation is 3 hours.6 

Styrene released to water is expected to have an evaporative 

half-life of 23.8 hours, assuming a water depth of 1 meter (3.28 

feet). In addition, styrene may be oxidized by some common water 

treatment compounds. Epichlorohydrin is formed in the presence 

of styrene and aqueous chlorine (hypochlorous acid).3 

Liquid styrene exposed to air results in polymerization of 

styrene initiated by ozone. As it polymerizes, styrene becomes 

increasingly viscous until .a clear, glossy solid is formed.' 

OVERVIEW OF PRODUCTION AND USE 

The total annual capacity of styrene manufacturing 

facilities in the United States was 4,075,142 Mg (8984 MM lbs) in 

1989.10 The majority of styrene is produced by dehydrogenation 

of ethylbenzene, with about 15 percent produced by 

hydroperoxidation of ethylbenzene. Propylene is a coproduct in 

the hydroperoxidation process. In 1989, eight companies at nine 

locations produced styrene in the United States. One additional 

facility has been on standby since 1985.10 The ethylbenzene used 

to manufacture styrene is produced by alkylation of benzene or 

extraction from mixed xylenes.11 Most ethylbenzene production 

processes are for captive styrene uses rather than for sale of 

the monomer.10 

•Styrene is manufactured as an intermediate for the 

production of polystyrene (68%), styrene-butadiene (SBR) 

| elastomers (6%), latexes (SBR latexes containing <45% styrene and 

| styrene-butadiene latexes containing >45% styrene) (7%), 

! acrylonitrile-butadiene styrene (ABS) resins and styreneacrylonitrile (SAN) (9%), unsaturated polyester resins (7%), and 

j for miscellaneous products and export (3%)." Seven of the eight 

styrene production facilities have some captive consumption of 

styrene monomer. Captively consumed monomer is mainly used for 

manufacturing polystyrene, but it is also used to a lesser extent 

to produce ABS, SAN, and styrene-butadiene copolymer latexes.13 

Figure 1 and Table 2 show some of the end products from styrene. 
P.21 

^ 

These products and some of their production processes will be 

covered in detail in Sections 5 and 6. Table 3 lists the 

potential source categories of styrene emissions by Standard 

Industrial Classification (SIC) code. It is important to note 

that these source categories db not necessarily denote 

significant sources of styrene emissions. 

10 
P.22 

Production Method Use Percent 

Ethylbenzene 

Dehydrogenatlon (85%) 

Ethylbenzene 

Hydroperoxidation (15%) 

Polystyrene 

Styrene butadiene 

(SBR) elastomer 

Styrene butadiene 

(SBR) latex (contains <45% 

styrene) and styrene-butadiene 

latex (contains >45% styrene) 

Unsaturated polyester resins 

Acrylonitrile-butadlene-styrene 

resins and styrene-acrylonttrile 

Miscellaneous and export 

68 

6 

7 

9 

Figure 1. Chemical Use Tree for Styrene12 

100 

11 
P.23 

TABLE 2. END USES OF STYRENE 

Polystyrene 

Styrene butadiene 

rubber (SBR) 

elastomers and 

latexes 

Styrene-butadiene 

(S-B) latexes 

Acrylonitrilebutadiene-styrene 

(ABS) 

Styreneacrylonitrile 

(SAN) 

Unsaturated 

polyester 

resins(reinforced 

plastics/ 

composites) 

Insulation board, loose-fill packaging, 

disposable dinnerware, food containers, 

toys, games, hobby kits, housings for 

room air conditioners and small handheld 

appliances, television cabinets, shower 

doors, drain pipes, tubing, light 

diffusers, audio and video tape 

cassettes, combs, brushes, eyeglasses, 

picnic coolers, molded shutters, 

furniture parts, watering cans, soap 

dishes, room dividers 

Passenger car tires, industrial hoses, 

conveyer belts, appliance parts, wire 

and cable insulation, footwear, coated 

fabrics, car bumpers and weatherstrips, 

additive in cements and adhesives 

Tufted carpet and upholstery ~ -

backcoatings, binder for paper coatings, 

binder for felt base of vinyl floor 

tile, cement additive, component of 

latex paints 

Piping (drain, waste, and vent), 

conduit, pipefittings, automotive 

components (instrument panels, consoles, 

front radiator grilles, headlight 

housings, etc.), refrigerator doorliners 

and food compartments, telephones, 

luggage and cases, toys, hobby kits, 

shower stalls and bathroom fixtures for 

mobile homes, margarine rubs, radio 

chassis 

Drinking tumblers, blender jars and 

covers, dishes, instrument panel lenses, 

battery cases 

Fiberglass reinforced boats, storage 

tanks, tub, spa, and shower units, truck 

camper tops, recreational vehicles, wall 

panels, cultured marble products, 

automotive parts, appliance/electrical 

components, and many other products. 

Source: Reference 8 

12 

•««*» . 
P.24 

TABLE 3. POTENTIAL SOURCE CATEGORIES OF STYRENE EMISSIONS 

SIC 

CODE" 

SOURCE DESCRIPTION 

1331 Crude petroleum and natural gas 

1321 Natural gas liquids 

1711 Plumbing, heating, air-conditioning 

1743 Terrazzo, tile, marble, mosaic work 

2221 Broadwoven fabric mills, manmade 

2262 Finishing plants, manmade 

2295 Coated fabrics, not rubberized 

2431 Millwork 

2434 Wood kitchen cabinets 

2492 Reconstituted wood products 

2499 Wood products, not elsewhere classified 

2511 Wood household furniture 

2517 Wood TV and radio cabinets 

2519 Household furniture not elsewhere classified 

2522 Office furniture, except wood 

2531 Public building and related furniture 

2599 Furniture and fixtures, not elsewhere classified 

265 PAPER AND ALLIED PRODUCTS 

2621 Paper mills 

2631 Paperboard mills 

265 Paperboard containers and boxes 

2655 Fiber cans, drums, and similar products 

2657 Folding paperboard boxes 

267 Miscellaneous converted paper products 

2672 Paper, coated and laminated, not elsewhere classified 

28 CHEMICALS AND ALLIED PRODUCTS 

281 Industrial gases 

2812 Inorganic pigments 

2813 Industrial inorganic chemicals, not elsewhere 

classified 

13 
P.25 

TABLE 3. (Continued) 

2816 Industrial pigments 

2819 Industrial inorganic chemicals, not elsewhere 

classified 

282 Plastics materials and synthetics 

2821 Plastics materials and resins 

2823 Cellulosic manmade fibers 

2833 Medicinals and botanicals 

2834 Pharmaceutical preparations 

2835 Diagnostic substances 

2836 Biological products (excluding diagnostic) 

2841 Soap and other detergents 

2842 Polishes and sanitation goods 

2843 Surface active agents 

2844 Toilet preparations 

2851 Paints and allied products 

286 Industrial organic chemicals 

2861 Gum and wood chemicals 

2865 Cyclic crudes and intermediates 

2869 Industrial organic chemicals, not elsewhere 

classified 

2873 Nitrogenous fertilizers 

2874 Phosphatic fertilizers 

2879 Agricultural chemicals, not elsewhere classified 

2891 Adhesive and sealants 

2892 Explosives 

2899 Chemical preparations, not elsewhere classified 

29 PETROLEUM AND COAL PRODUCTS 

2911 Petroleum refining 

2951 Asphalt paving mixtures and blocks 

2992 Lubricating oils and greases 

2999 Petroleum and coal products, not elsewhere classified 

14 
P.26 

TABLE 3. (Continued) 

30 RUBBER AND MISCELLANEOUS PLASTICS PRODUCTS 

3011 Tires and inner tubes 

3021 Rubber and plastics footware 

3052 Rubber and plastics hose and belting 

3069 Fabricated rubber products, not elsewhere classified 

308 Miscellaneous plastics'products, not elsewhere 

classified 

3081 Unsupported plastics film and sheet 

3082 Unsupported plastics profile shapes 

3083 Laminated plastics plate and sheet 

3084 Plastics pipe 

3086 Plastics foam products 

3087 Custom compound purchased resins 

3088 Plastic plumbing fixtures 

3089 . Plastics products,.not elsewhere classified 

3142 House slippers 

3229 Pressed and blown glass, not elsewhere classified 

3241 Cement, hydraulic 

3261 Vitreous plumbing fixtures 

3271 Concrete block and brick 

3272 Concrete products, not elsewhere classified 

3274 Lime 

3281 Cut stone and stone products 

3291 Abrasive products 

329 Mineral wool 

3299 Non-metallic mineral products, not elsewhere 

classified 

3312 Blast furnaces and steel mills 

3313 Electrometallurgical products 

316 Cold finishing of steel shapes 

3321 Gray and ductile iron foundries 

3324 Steel investment foundries 

15 
P.27 

TABLE 3. (Continued) 

3325 Steel foundries, not elsewhere classified 

3339 Primary nonferrous metals, not elsewhere classified 

3341 Secondary nonferrous metals 

3363 Aluminum die-casting 

3364 Nonferrous die-casting, excluding aluminum 

3365 Aluminum foundries 

3366 Copper foundries 

3369 Nonferrous foundries, not elsewhere classified 

34 FABRICATED METAL PRODUCTS 

3423 Hand and edge tools, not elsewhere classified 

343 Plumbing and heating, except electric - - -

3431 Metal sanitary ware 

344 Fabricated structural metal products 

3441 Fabricated structural metal 

3442 Metal doors, sash, and trim 

3343 Fabricated plate work (boiler shops) 

3444 Sheet metal work 

3446 Architectural metal work 

3451 Screw machine products 

3479 Metal coating and allied services 

3498 Fabricated pipe and fittings 

3499 Fabricated metal products, not elsewhere classified 

3511 Turbines and turbine generator sets 

3519 Internal combustion engines, not elsewhere classified 

352 Farm and garden machinery 

3523 Farm machinery and equipment 

3533 Oil and gas field machinery 

3541 Machine tools, metal cutting types 

3546 Power-driven handtools 

16 
P.28 

TABLE 3. (Continued) 

3548 Welding apparatus 

3561 Pumps and pumping equipment 

3563 Air and gas compressors 

3564 Blowers and fans 

3575 Computer terminals 

3585 Refrigeration and heating equipment 

3599 Industrial machinery, not elsewhere classified 

3612 Transformers, except electronic 

3613 Switchgear and switchboard apparatus 

3621 Motors and generators 

3624 Carbon and graphite products 

3625 Relays and industrial controls 

3643 Current-carrying wiring devices 

3644 Noncurrent-carrying wiring devices 

3647 Vehicular lighting equipment 

3661 Telephone and telegraph apparatus 

3663 Radio and TV communications equipment 

367 Electric components and accessories 

3671 Electron tubes 

3674 Semiconductors and related devices 

3679 Electronic components, not elsewhere classified 

3694 Engine electrical equipment 

37 TRANSPORTATION EQUIPMENT 

^371 Motor vehicles and equipment 

3711 Motor vehicles and car bodies 

3713 Truck and bus bodies 

3714 Motor vehicles parts and accessories 

3715 Truck trailers 

3716 Motor homes 

17 
P.29 

TABLE 3. (Continued) 

A 

3721 Aircraft 

373 Ship and boat building and repairing 

3731 Ship building and repairing 

3732 Boat building and repairing 

3792 Travel trailers and campers 

3799 Transportation equipment, not elsewhere classified 

3812 Search and navigation equipment 

3821 Laboratory apparatus and furniture 

3826 Analytical instruments 

3829 Measuring and controlling devices, not elsewhere 

classified ~ ~ 

3842 Surgical appliances and supplies 

3844 X-ray apparatus and tubes 

3861 Photographic equipment and supplies 

39 MISCELLANEOUS MANUFACTURING INDUSTRIES 

3931 Musical instruments 

394 Toys and sporting goods 

3944 Games, toys, and children's vehicles 

3949 Sporting and athletic goods, not elsewhere classified 

3965 Fasteners, buttons, needles, and pins 

3999 Manufacturing industries, not elsewhere classified 

4225 General warehousing and storage 

4226 Special warehousing and storage, not elsewhere 

classified 

4231 Trucking terminal facilities 

4991 Marine cargo handling 

4612 Crude petroleum pipelines 

4953 Refuse systems 

4961 Steam and air-conditioning supply 

5091 Sporting and recreational goods 

18 
P.30 

TABLE 3. (Continued) 

516 Chemicals and allied products 

5171 Petroleum bulk stations and terminals 

6512 Nonresidential building operators 

6514 Dwelling operators, excluding apartments 

7389 Business services, not elsewhere classified 

7999 Amusement and recreation, not elsewhere classified 

8062 General medial and surgical hospitals 

8731 Commercial physical research 

8999 Services, not elsewhere classified 

*SIC Code is listed as a potential source in the EPA "Crosswalk" 

document.13 The data in Crosswalk were obtained primarily from 

permitting and source test information contained in the 1986 

National Air Toxics Information Clearinghouse (NATICH) data base. 

Additional data were gathered from the Organic Chemical 

Producers' Data Base and Air Emissions Species Data Manual 

(Volume I, Volatile Organic Compound Species profiles), and SARA 

313 Toxic Release Inventory.13 

\ 

19 
P.31 

REFERENCES FOR SECTION 3 

1. Chemical and Engineering News. Facts and Figures for the 

Chemical Industry at a Glance, pp. 36-45. June 1989. 

2. National Research Council. The Alkyl Benzenes. Committee 

on Alkyl Benzene Derivatives; Board on Toxicology and 

Environmental Health Hazards; Assembly of Life Science. 

National Academy Press. 1981. 

3. Santodonato, J., et al. Investigation of Selected Potential 

Environmental Contaminants: Styrene, Ethylbenzene, and 

Related "Compounds. EPA-560/11-80-018. U. S. Environmental 

Protection Agency, Washington, D.C. 1980. 

4. Pope, A. A., et al. Toxic Air Pollutant Emission Factors -

A Compilation for Selected Air Toxic Compounds and Sources. 

EPA-450/2-88-006. U. S. Environmental Protection Agency, 

Research Triangle Park, North Carolina. 1988. 

5. Pfaffli, P., et al. Thermal Degradation Products of 

Homopolymer Polystyrene in Air. Scand. J. Work Environ, and 

Health. Suppl. 2:22-27. 1978. 

6. Alexander, M. The Environmental Fate, of Styrene. The SIRC 

Review, pp. 33-42. April 1990. 

7. Kirk-Othmer Encyclopedia of Chemical Technology. 3rd ed. 

Styrene. Volume 21. John Wiley and Sons. New York, New 

York. pp. 770-801. 1983. 

8. U. S. Department of Health and Human Services. Criteria for 

a Recommended Standard. Occupational Exposure to Styrene. 

DHHS (NIOSH) Publication No. 83-119. National Institute for 

Occupational Safety and Health, Cincinnati, Ohio. 1983. 

9- Lowenheim, F. A. and M. K. Moran. Styrene. In: Faith, 

Keyes, and Clark's Industrial Chemicals. John Wiley and 

Sons. New York, New York. pp. 779-785. 1975. 

10. SRI International. 1989 Directory of Chemical Producers, 

United States of America. Menlo Park, California. 1989. 

11. U. S. Environmental Protection Agency. Benzene Emissions 

from the Ethylbenzene/Styrene Industry - Background 

Information for Proposed Standards. EPA-450/3-70-035a. 

Research Triangle Park, North Carolina. 1980. 

12. A. T. Kearney. Impact Analysis of the EPA Office of 

Drinking Water Proposal to Regulate Styrene. Styrene 

Information Research Center. 1989. 

20 
P.32 

13. Pope, A. A., et al. Toxic Air Pollutant/Source Crosswalk 

A Screening Tool for Locating Possible Sources Emitting 

Toxic Air Pollutants, Second Edition. EPA-450/2-89-017. 

U. S. Environmental Protection Agency, Research Triangle 

Park, North Carolina. 1989. 

21 
P.33 

22 
P.34 

SECTION 4 

EMISSIONS FROM STYRENE PRODUCTION 

Styrene production and the associated air emissions are 

described in this section. Process flow diagrams are included as 

appropriate, with specific streams or vents in the figures 

labeled to correspond with the discussion in the text. Emission 

factors for the production processes are presented when 

available, and control technologies are described. The reader 

should contact the specific facility to verify the nature of the 

process used, production volume, and controls in place before 

applying any of the emission factors presented. 

Styrene is currently produced by eight companies at nine 

locations in the United States. One additional facility has been 

on standby since 1985 and is not currently manufacturing styrene. 

The production locations and capacities are presented in Table 4. 

The total annual capacity for all styrene manufacturing 

facilities is 4,075,142 Mg (8984 MM lbs) (not including the plant 

on standby),1 with facilities operating at 98 percent of 

capacity.2 As shown in Figure 2, the majority of styrenemanufacturing facilities are located on the Gulf Coast. 

All but one plant manufactures styrene by dehydrogenation of 

ethylbenzene. The other facility uses hydroperoxidation of 

ethylbenzene to produce propylene, with styrene as a by-product. 

PROCESS DESCRIPTION 

Ethylbenzene Dehydrogenation 

The majority of styrene produced in the United States is 

produced by the dehydrogenation of ethylbenzene. Seven 

facilities have the capacity to produce an annual total of 

3,480,926 Mg (7674 MM lbs). 

23 
P.35 

TABLE 4. STYRENE PRODUCTION LOCATIONS AND CAPACITIES 

Facility 

Amoco Corporation 

ARCO Chemical Co. 

Chevron Corporation 

Cos-Mar, Inc. 

Dow chemical 

Huntsman Chemical Corp. 

Rexene Products Co. 

Sterling Chemicals, Inc. 

Location 

Texas City, TX 

Channelview, TX* 

Monaca, PA 

St. James, LA 

Carville, LA 

Freeport, TX 

Midland, MIb 

Bayport, TX 

Odessa, TX 

Texas City, TX 

Annual Capacity 

Mg/yr 

362,880 

594,216 

99,792 

272,160 

680,400 

639,576 

146,966 

.453,600 

145,152 

680,400 

4,075,142 

MM 

lb/yr 

800 

13i0 

220 

600 

1500 

1410 

324 

1000 

320 

1500 

8984 

"Ethylbenzene hydroperoxidation process. 

"Plant has been on standby since 1985 (not included in total 

capacity). 

NOTE: This listing is subject to change as market conditions 

change, facility ownership changes, plants are closed down, etc. 

The reader should verify the existence of particular facilities 

by consulting current listings and/or the plants themselves. The 

level of styrene emissions from any given facility is a function 

of variables such as capacity, throughput, and control measures, 

and should be determined through direct contacts with plant 

personnel. These operating plants and locations were current as 

of January 1990. 

Source: Reference 1 

24 
P.36 

1. 

2. 

3. 

4. 

5. 

LEGEND OF PLANT NAMES ANO LOCATIONS 

ARCO, Monaca, PA 6. Dow, Midland, Ml 

Chevron, St. James, LA 7. Rexene Products Co., Odessa, TX 

Huntsman Chemical, Bayport, TX 8. Amoco Corporation, Texas City, TX 

Cos-Mar, Carville, LA 9. ARCO, ChanneMew, TX 

Dow, Freeport, TX 10. Sterling Chemicals, Texas City, TX 

Figure 2. Locations of Plants Manufacturing Styrene 

25 
P.37 

Styrene manufacture by ethylbenzene dehydrogenation is shown by 

the reaction: 

+ 

Ethylbenzene Styrene Hydrogen 

Figure 3 illustrates the process of ethylbenzene 

dehydrogenation. Purified ethylbenzene is preheated in a heat 

exchanger (Step 1), and the resultant vapor is mixed continuously 

with steam at 710°C in the dehydrogenation reactor (Step 2) that 

contains one of several catalysts such as zinc, aluminum, 

chromium, iron, or magnesium oxide. The reaction product exits 

through the heat exchanger and is further cooled in a condenser 

where water and crude styrene vapors are condensed (Step 3). The 

hydrogen-rich process gas is recovered and used as a fuel (Step 

4) and the process water is purified in a stripper (Step 5) and 

recycled to the boiler. The remaining crude liquid styrene goes 

to a storage tank (Step 6). The liquid consists of styrene 

(37%), ethylbenzene (61%), toluene (1%), benzene (0.7%) and tars 

(0.3%). Benzene and toluene are removed from the crude styrene 

in the benzene/toluene column (Step 7). They are then typically 

separated by distillation. The toluene is sold and the benzene 

is returned to the ethylbenzene production section or sold. 

Next, the ethylbenzene column removes ethylbenzene that is 

directly recycled (Step 8). Tars are removed and the styrene 

product emerges from the styrene finishing column (Step 9). In 

some facilities, an ethylbenzene/benzene/toluene stream is 

separated from the crude styrene initially and processed 

separately. 

Ethylbenzene Hydroperoxidation 

Styrene is currently manufactured by ethylbenzene 

hydroperoxidation at only one facility in the United States. 

26 
Ethylbenzene Production 

Benzene Recycle 

Column 

Toluene 

Storage 

Steam 

to 

-J Steam 

Superheater 

Denotes potential location 

of emission source 

Dehydrogenation 

Reaction Section 

Hydrogen 

Separation Section 

Styra 

ficatlor 

rerte 

.Purification Section 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 3. Process Flow Diagram for Styrene Production by Ethylbenzene 

Dehydrogenation 
P.39 

This process, shown in Figure 4, is described below. Styrene 

manufacture by ethylbenzene hydroperoxidation is shown by the 

reaction: 

Qqrgan Propytana Odd* Water 

Ethylbenzene is oxidized with air to produce ethylene 

hydroperoxide and small amounts of methylbenzylalcohol and 

acetophenone (Step 1). The exit gas (principally-nitrogen) is 

cooled and scrubbed to recover aromatics before venting. 

Unreacted ethylbenzene and low-boiling contaminants are removed 

in an evaporator (Step 2). Ethylbenzene is then sent to the 

recovery section to be treated before reuse (Step 3). 

The mixed stream of methylbenzylalcohol and acetophenone is 

then dehydrated over a solid catalyst to produce styrene 

(Step 4). Residual catalyst solids and high-boiling impurities 

are separated and collected for disposal. The crude styrene goes 

to a series of distillation columns where the pure styrene 

monomer product is recovered (Step 5). The residual organic 

stream contains crude acetophenone, catalyst residue, and various 

impurities. This mixture is treated under pressure with hydrogen 

to convert the acetophenone to methylbenzylalcohol (Step 6). 

Catalyst waste is separate from the methylbenzylalcohol which is 

returned to the recovery section for processing and reuse. 

Hydrogen and organic vapors are recovered for use as fuel. 

Ethylbenzene hydroperoxide is combined with propylene over a 

catalyst mixture under high pressure to produce propylene oxide 

and acetophenone (Step 7). Pressure is then reduced and residual 

propylene and other low-boiling compounds are separated by 

distillation (Step 8). The vent stream containing propane and 

some propylene can be used as a fuel. Propylene is recycled to 

the epoxidation reactor. The crude epoxidate is treated to 

28 
Air 

Hydroperoxidation 

Reactor 

Evaporation 

EB 

ACP 

MBA 

© 

EB 

EB 

Hydroperoxide 

EB 

VO 

Propylene 

Epoxidatlon 

Reactor © 

EB 

MBA 

ACP 

SM 

LEGEND 

Ethylbenzene 

Methylbenzylalcohol 

Acetophenone 

Styrene Monomer 

Dehydration 

Crude 

SM 

© 

© 

t 

Styrene 

Refining 

EB.MBA 

Recovery 

Section 

<: 

MBA 

rMD 

5 ) , 

ACP 

Dehydrogenation 

\"2 

© 

Propam ^ 

s 

Recycle Propylene 

lene 

Distillation © 

Caustic and 

Water Wash 

© 

Propylene 

Oxide 

Distillation 

Recycled 

Wash Water 

© 

© 

Styrene 

Storage 

Catalyst Waste 

-Vapor Fuels 

-Vapor Fuels 

Propylene 

Ide 

© 

Loading 

( Fugitives from 

overall process 

( Secondary 

sources 

( Storage and 

InnHInn lassa loading losses 

Denotes potential location 

of emission source 

Figure 4. Process Flow Diagram for Styrene Production by Ethylbenzene 

Hydroperoxidation

 4 
P.41 

remove acidic impurities and residual catalyst material (Step 9) 

and the resultant epoxidate stream is distilled (Step 10) to 

separate the propylene oxide product for 'storage. Residual water 

and propylene are recycled to the process train and liquid 

distillate is recovered as a fuel. The organic layer is routed 

to the ethylbenzene and methylbenzylalcohol recovery section. 

Isothermal Processing 

An isothermal process for producing styrene from 

ethylbenzene was patented in the United states in 1981.9 This 

process is not currently used in the United States, but it is 

used in several European countries. - ~ 

As shown in Figure 5, liquid ethylbenzene is vaporized by 

condensing steam in a heat exchanger (Step 1). Process steam is 

then introduced into the ethylbenzene stream and the feed mixture 

is superheated before it enters the molten-salt reactor (Step 2). 

In the reactor, the ethylbenzene/steam mixture passes 

through tubes where it comes into contact with the catalyst and 

is dehydrogenated. Heat for the dehydrogenation reaction is 

supplied by molten salt (preferably a mixture of sodium 

carbonate, lithium carbonate, and potassium carbonate) 

surrounding the tubes. The reactor is maintained at a uniform 

wall temperature by circulating the molten-salt mixture through 

the heat exchanger of a fired heater. 

The reaction products are cooled and condensed in a 

separator (Step 3). The liquid phase is a mixture of organic 

products: styrene, unreacted ethylbenzene, and small quantities 

of benzene, toluene, and high-boiling compounds. Styrene is 

separated from the other liquid constituents, which are then 

recovered and recycled. 

30 
u> 

Air Preheater 

Steam 

Generator 

Cooler 

Salt Bath 

Heater 

Fuel 

Ethylbenzene 

(liquid) -

Molten Salt 

Motor Mixer kA 

Ethylbenzene 

(vapor) 

Isothermal 

Reactor 

© 

© 

Compressor 

Heat 

Exchanger 

® 

Steam 

Steam-

© 

© 

' T© ^^^ © 

— • - Gas 

(returns to reactor 

as fuel) 

Separator © 

Styrene 

Storage 

Fugitives from 

overall process 

Secondary 

sources 

Storage and 

loading losses 

© i \Z^ 

Loading 

Denotes potential location 

of emission source 

Figure 5. Process Flow Diagram for Styrene Production by Isothermal Processing 
P.43 

The gas phase from the condensation step in the separator 

consists mainly of hydrogen, with small quantities of carbon 

dioxide, carbon monoxide, and methane. After these gases are 

compressed, they are cooled. Condensable products from this 

final cooling stage are then recovered and recycled to the 

separator. When hydrogen-rich' offgas is used as fuel for the 

heater of the molten-salt reactor, the fuel requirement for this 

stage of the process is zero. 

EMISSIONS 

Most air emissions associated with styrene production arise 

from loading operations, styrene monomer storage, and equipment 

leaks. Process vents may also contribute to air emissions in 

addition to secondary sources (such as waste treatment and 

disposal facilities). 

Process Emissions 

Figure 3 shows that during styrene production by 

ethylbenzene dehydrogenation, process vent discharges (A) of 

styrene occur primarily from the vacuum column vents. The 

hydrogen separation vent is only used during startup, shutdown, 

and during recovery section outages.* The vacuum column vents 

remove air that leaks into the column, as well as light 

hydrocarbons and hydrogen that form during dehydrogenation, 

noncombustibles dissolved in the column feed, and any entrained 

aromatics. The majority of styrene emissions occur at the first 

column, the benzene-toluene column, in the distillation train. 

Although no specific information on controls was available, 

process vents that have the potential to emit benzene may be 

controlled to prevent occupational exposure. 

Other sources of process emissions from ethylbenzene 

dehydrogenation are less likely because of the need to operate 

most processes under a vacuum and because of the heating value of 

the gases. No emission estimates for styrene production 

32 
P.44 

processes were located in the literature. Also, little 

information was found on emission controls. One type of control 

option is incineration, which can reduce styrene emissions by as 

much as 98 percent.* 

No information was located in the literature that discussed 

process emission sources from styrene production by ethylbenzene 

hydroperoxidation or the isothermal production process. Styrene 

emissions may occur during the styrene refining process for each 

of these production processes. 

Storage Emissions 

Other possible sources of styrene emissions are storage tank 

losses (B) and handling losses (C) that occur during product 

loading into drums, tank trucks, tank cars, barges, or ships. 

Styrene production plants typically have from 2 to 12 small, 

i 

fixed-roof monomer storage tanks. Storage tank losses are either 

working losses that occur while filling the tank, or breathing 

losses due to expansion from temperature changes. Both can be 

estimated using equations for storage tank emissions given in the 

U. S. Environmental Protection Agency's "Estimating Air Toxic 

Emissions from Organic Liquid Storage Tanks" report.6 in the 

absence of specific data on the storage tank, two emission 

factors were identified in the literature.7 Shown in Table 5, 

both are for uncontrolled emissions. No facilities are known to 

currently control emissions with floating roof tanks or 

incineration, although several use condensing units to recover 

styrene.2 

Eguipment Leak Emissions 

Emissions occur from process equipment components whenever 

the liquid or gas streams leak from the equipment. Equipment 

leaks can occur from the following components: pump seals, 

33 
P.45 

TABLE -5. STYRENE STORAGE AND SECONDARY EMISSION FACTORS 

Emission Source 

Storage 

Breathing Loss' 

Working Loss* 

Estimated Emission Factor 

0.18 g/L (1.5 lbs/10 lbs) storage 

capacity 3 

0.02 g/L (0.17 lbs/10 lbs) gallons 

throughput 

Secondary 

Wastewater Treatment*1 0.50 g/g (0.50 lb/lb) styrene in 

"Source: Reference 7. 

Source: Reference 8. 

wastewater 

34 
P.46 

process valves, compressor safety relief valves, flanges, openended lines, and sampling connections. Fugitive emissions will 

be primarily limited to the streams containing no benzene because 

of the National Emission Standard for Hazardous Air Pollutants 

(NESHAP) that applies to equipment in benzene service. This 

NESHAP addresses all equipment components handling process 

streams containing 10 percent by weight or greater benzene. 

Emission estimates can be calculated in the five ways described 

in the EPA publication "Protocols for Generating Unit-Specific 

Emission Estimates."9 The methods differ in complexity; however, 

the more complex, the better the emission estimate. 

The simplest method requires that the number of each 

component type be known. Furthermore, for every component the 

styrene content of the stream and the time the component is in 

service is needed. This information is then multiplied by the 

EPA's average emission factors for the Synthetic Organic Chemical 

Manufacturing Industries (SOCMI) shown in Table 6. This method 

should only be used if no other data are available, as it 

probably results in an overestimation of actual equipment leak 

emissions. For each component, estimated emissions are: 

No. of 

equipment 

components. 

Weight % 

styrene in the 

stream 

Component-specific 

emission factor 

No. hrs/yr in 

styrene service 

To obtain better equipment leak emission estimate? 

the more complex estimation methods, should *~ 

four methods require that some level of emi 

the facility's equipment components be coll 

described briefly, and the reader is referre 

document for the calculation details. 

/ 

A 

Ater may 

35 
P.47 

TABLE 6. AVERAGE EMISSION FACTORS FOR FUGITIVE EMISSIONS 

Equipment Service 

Emission Factor 

(Kg/hr/ 

Source) 

(Lb/hr/ 

Source) 

Valves 

Pump Seals 

Compressor Seals 

Pressure Relief 

Seals 

Flanges 

Open-Ended Lines 

Sampling Connections 

Gas 

Light Liquid 

Heavy Liquid 

Light Liquid 

Heavy Liquid 

Gas/Vapor 

Gas/Vapor 

All 

All 

All 

0.0056 

0.0071 

0.00023 

0.0494 

0.0214 

0.228 

0.104 

0.00083 

0.0017 

0.0150 

0.012 

0.016 

0.00051 

0.109 

0.472 

0.503 

0.229 

0.0018 

0.0037 

0.033 

Source: Reference 9. 

36 
P.48 

The leak/no leak approach is based on a determination of the 

number of leaking and non-leaking components. These values are 

then multiplied by two different sets of EPA-derived emission 

factors. The third method groups screening results into three 

ranges: 0-1,000 ppmv; 1,001-10,000 ppmv; and greater than 10,000 

ppmv. The number of each component falling in a particular range 

is multiplied by the component-specific emission factor for that 

range. These emission factors have also been developed by EPA. 

The fourth procedure uses screening data in correlation equations 

derived from earlier work by EPA. 

The fifth method gives the facility the option to develop 

its own correlation equations but requires more rigorous testing, 

bagging and analyzing of equipment leaks to determine mass 

emission rates. 

Although no specific information on controls used by the 

industry was identified, equipment components in benzene service 

will have some controls in place. Generally, control of fugitive 

emissions will require the use of sealless or double mechanical 

seal pumps, an inspection and maintenance program, as well as 

replacement or leaking valves and fittings. Typical controls for 

equipment leaks are listed in Table 7. Additionally, some 

leakless equipment is available such as leakless valves10 and 

sealless pumps.2 

Secondary Emissions 

Secondary emissions occur at both on-site and off-site 

facilities that treat and dispose of wastewater, liquid waste, or 

solid waste. Waste streams may be generated for any of the 

operations shown in Figures 3, 4, and 5. 

For secondary emissions resulting from treatment of 

wastewater containing styrene, one reference estimated that 

approximately 50 percent of the styrene present in the water may 

37 
TABLE 7. CONTROL TECHNIQUES AND EFFICIENCIES 

APPLICABLE TO EQUIPMENT LEAK EMISSIONS 

Equipment Component 

(Emission Source) 

Pump Seals 

Packed and Mechanical 

CJ 

03 

Double Mechanical1 

Compressors 

Flanges 

Valves 

Gas 

Liquid 

Control Technique 

Seal area enclosure vented to a 

combustion device 

Monthly LDARb 

Quarterly LDAR 

Semiannual LDAR 

Annual LDAR 

N/Ad 

Vent degassing reservoir to combustion 

device 

None available 

Monthly LDAR 

Quarterly LDAR 

Semiannual LDAR. 

Annual LDAR 

Monthly LDAR 

Quarterly LDAR 

Semiannual LDAR 

Annual LDAR 

Percent 

Reduction" 

100 

61 

32 

0 

0 

100 

0 

73 

64 

50 

24 

59 

44 

22 

0 
TABLE 7. (Continued) 

u> 

VO 

Pressure Relief Devices 

Gas Monthly LDAR 50 

Quarterly LDAR 44 

Rupture Disk 100 

Liquid N/A 

Sample Connections Closed-purge sampling 100 

Open-ended Lines Caps on open ends 100 

"If Reference 10 indicated a negative reduction for a control technique, zero was used. 

*LDAR = Leak detection and repair. 

cAssumes the seal barrier fluid is maintained at a pressure above the pump stuffing box 

pressure and the system is equipped with a sensor that detects failure of the seal and/or 

barrier fluid system. 

dN/A = Not applicable. There are no VOC emissions from this component. 

Source: References 2 and 10. 

Y 
P.51 

be released during processing at a publicly owned treatment works 

(POTW) facility.11 This emission factor is given in Table 5. No 

information was available on the styrene content in the 

wastewater. Furthermore, handling and processing practices will 

differ with each facility; therefore, the emission factor should 

be.reviewed as providing an order-of-magnitude estimate at best. 

y 

40 

V 
P.52 

REFERENCES FOR SECTION 4 

1. SRI International. 1990 Directory of Chemical Producers, 

United states of America. Menlo Park, California. 1990. 

2. A. T. Kearney. Impact Analysis of the EPA Office of 

Drinking Water Proposal to Regulate Styrene. Styrene 

Information Research Center. 1989. 

3. U. S. Environmental Protection Agency. Benzene Emissions -

from the Ethylbenzene/Styrene Industry - Background 

Information for Proposed Standards. EPA-450/3-70-035a. 

U. S. Environmental Protection Agency, Research Triangle 

Park, North Carolina. 1980. 

4. Cruse, P. A. Locating and Estimating Air Emissions from 

Sources of Benzene. EPA-450/4-84-007q. U. S. Environmental 

Protection Agency, Research Triangle Park, North Carolina. 

1988. 

5. Short, H. C. and L. Bolton. New Styrene Process Pares 

Production Costs. Chemical Engineering. August: 30-31. 

1985. 

6. Murphy, P. Estimating Air Toxics Emissions From Organic 

Liquid Storage Tanks. EPA-450/4-88-004. U. S. 

Environmental Protection Agency, Research Triangle Park, 

North Carolina. 1988. 

7. Stockton, M. B. and J. H. E. Stelling. Criteria Pollutant 

Emission Factors for the 1985 NAPAP Emissions Inventory. 

EPA-600/7-87-015. U. S. Environmental Protection Agency, 

Washington, D.C. p. 134. 1987. 

8. Pope, A. A., et ai. Toxic Air Pollutant Emission Factors -

A Compilation for Selected Air Toxic Compounds and Sources. 

EPA-450/2-88-006. U. S. Environmental Protection Agency, 

Research Triangle Park, North Carolina. 1988. 

9. U. S. Environmental Protection Agency. Protocols for 

Generating Unit-Specific Emission Estimates for Equipment 

Leaks of VOC and VHAP. EPA-450/3-88-010. U. S. 

Environmental Protection Agency, Research Triangle Park, 

North Carolina. 1988. 

10. U. S. Environmental Protection Agency. Fugitive Emission 

Sources of Organic Compounds—Additional Information on 

Emissions, Emission Reductions, and Costs. EPA-450/3-82-

010. U. S. Environmental Protection Agency, Research 

Triangle Park, North Carolina. April 1982. 

41 
P.53 

11. White, T. S. Volatile Organic Compound Emissions from 

Hazardous Waste Treatment Facilities at Downstream POTW. 

Prepared for the U. S. Environmental Protection Agency, 

Research Triangle Park, North Carolina, pp. 5-6. 1987. 

42 
P.54 

SECTION 5 

EMISSIONS FROM MAJOR USES OF STYRENE 

This section discusses emissions from major industrial 

processes that use styrene as a feedstock. The processes 

described are production of polystyrene (PS) polymer, styrenebutadiene copolymers (S-B, SBR), styrene-acrylonitrile copolymer 

(SAN), acrylonitrile-butadiene-styrene copolymer (ABS), and 

unsaturated polyester resins (UPR). In addition, product and 

process descriptions are provided for the miscellaneous styrene 

copolymers: styrene-butadiene-vinylpyridine (SBV) latex, methyl 

methacrylate-butadiene-styrene (MBS) resins, and methyl 

methacrylate-acrylonitrile-butadiene-styrene (MABS) polymer. 

Process flow diagrams are included as appropriate, with specific 

streams or vents in the figures labeled to correspond with the 

discussion in the text. 

Emissions of styrene are expected from all facilities that 

produce the above listed resins. However, insufficient 

information is available to develop emission factors for 

fugitives or process emission sources. Available information is 

provided in each subsection. The reader is encouraged to contact 

State or local air pollution control agencies, the toxic release 

inventory, and specific production facilities for information on 

styrene emissions and control technologies. 

POLYSTYRENE PRODUCTION 

Polystyrene is produced by the polymerization of styrene 

monomer. The polymer is available in a wide range of 

formulations including crystal, high impact and expandable (EPS). 

Crystal PS is the general purpose grade.. It is a clear, rigid 

plastic with excellent electrical and insulation properties and 

low impact resistance.1 To increase the toughness of the 

polystyrene plastic, rubber particles (usually polybutadiene) may 

43 
P.55 

be incorporated into the polymer matrix. This rubber-modified 

form is known as high impact PS.2 Expandable polystyrene is 

produced by the addition of a volatile blowing agent to the 

polystyrene which causes the polymer to expand when heated. The 

blowing agent may be added during the polymerization process or 

during the fabrication process.3 

Polystyrene is used in injection and extrusion processes to 

produce a wide variety of products. The major end use for PS is 

in packaging. The resin also finds applications in the building, 

electronics, furniture, housewares, and recreational marketing 

areas. Polystyrene is the leading resin used for making toys. 

Injection molding is used to make products such as tumblers, 

tooth brush handles, computer disk reels, pill bottles, and toys. 

Extrusion is used to make egg cartons, meat/poultry trays, and 

fast-food packages. Crystal PS is used to make fast-food 

packages and egg cartons. High impact PS is used to produce 

fast-food cups, lids, and containers, toys, containers for food, 

fruit juices, and dairy products, kitchen housewares, and small 

appliances. Expandable PS, which is easy to process, is used to 

make disposable drinking cups, loose fill packaging, insulation, 

and packaging shapes. Polystyrene is commonly marketed in bead 

or pellet form; however, some is captively converted to film, 

sheet, or foam.* 

Polystyrene is currently produced by 17 companies at 34 

facilities in 16 States. These facilities and their 1990 

production capacities are listed in Table 8.s Manufacture of 

polystyrene is the major end use of styrene monomer, consuming 

approximately 68 percent of the styrene produced in the United 

States.6 

Process Description 

Polystyrene may be produced by the suspension, mass (bulk), 

solution, and emulsion processes. The suspension process is 

44 
P.56 

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TABLE 8. (Continued) 

Akron, OH 

Decatur, AL 

Leominster, MA 

Springfield, MA 

Fort Worth, TX 

City of Industry, CA 

TOTAL 

54,431 

63,503 

72,575 

71,647 

34,927 

29,948 

3,045,419* 

-

120 

140 

160 

180 

77 

55 

6,714 

cn 

Polysar 

Scott Polymers 

Tenneco 

'Numbers do not total due to rounding. 

NOTE: The listing on Table 8 is subject to change as market conditions change, facility 

ownership changes, plants are closed down, etc. The reader should verify the existence of 

particular facilities by consulting current listings and/or the plants themselves. The 

level of styrene emissions from any given facility is a function of variables such as 

capacity, throughput, and control measures, and should be determined through direct 

contact with plant personnel. These operating plants and locations were current as of 

January 1990. 

Source: Reference 5. 
P.58 

operated in a batch mode, whereas the mass and solution processes 

are operated in the continuous mode.7 The mass and suspension 

methods are commercially significant.7 Use of the emulsion 

process for PS production has decreased significantly since the 

mid-1940's.* It is not used for the production of crystal PS 

because the soap solution (emulsifier) adversely affects the 

clarity and electrical-insulation characteristics of the 

product.3 Therefore, the emulsion process will not be discussed 

here. 

To produce impact grade polystyrene, the rubber component 

may be incorporated by mechanical means after styrene 

polymerization or it may be added to the polymerization reactor 

along with the styrene monomer. If mechanical means are used, 

rubber latex may be added to polystyrene latex followed by 

coagulation and drying, or dry rubber can be milled with dry 

polystyrene. Alternatively, chopped preformed unsaturated rubber 

can be dissolved into styrene monomer and then the mixture can 

undergo polymerization by any of the three processes described 

below.3 Most impact PS is produced by suspension 

polymerization.3 

Expandable polystyrene is produced by modifying the batch 

suspension process. A blowing agent, such as n-pentane, may be 

added to the reactor before or after polymerization and is 

absorbed by the polystyrene. The post-impregnation process is 

more commonly used.8 In this method the finished polystyrene 

product bead from the suspension process is fed through a second 

suspension process train where the blowing agent is impregnated 

into the product beads through the use of temperature and applied 

pressure. 

47 
Suspension Process— 

The suspension process (Figure 6) is a batch polymerization 

process that may be used to produce crystal, impact or expandable 

polystyrene beads. In this process, polymerization is carried 

out in an aqueous medium to permit removal of the heat of there 

action.1 The polystyrene polymer is formed in small beads which 

are easily separated from the aqueous phase. 

Styrene monomer from storage is first washed to remove any 

inhibitors of the polymerization reaction (Step l). The washed 

styrene is transferred to a mixing tank where it is combined with 

a free radical initiator (Step 2). The styrene is then fed into 

an agitated reactor along with water, initiator, a monomer 

soluble suspending agent and suspension stabilizer (Step 3). A 

blowing agent or rubber may be added at this time for the 

production of expandable PS or high impact PS respectively. Both 

the blowing agent and the rubber may also be added later as part 

of a post polymerization process. Following polymerization, the 

polymer beads are transferred to a wash tank where they are 

washed with acid to remove initiators and suspension stabilizers 

(Step 4). The wet beads are sent to a centrifuge (Step 5) and 

then a dryer (Step 6) for dewatering and drying. The beads are 

passed to a devolatilization extruder for recovery of unreacted 

styrene monomer (Step 7). Recovered monomer is recycled into the 

polymerization reactor. The purified polymer beads are dried and 

sent to product storage.3 

Mass Process— 

The mass process uses no water or organic solvents and is 

the simplest process for producing polystyrene. As shown in 

Figure 7, there are four major stages in the mass process: 

prepolymerization, polymerization, devolatilization, and 

extrusion. Styrene monomer is stripped of inhibitors in a steam 

stripper (Step 1) then pumped into a stirred prepolymerization 

48 

I 
vo 

Styrene -

SteamX 

Monomer 

Wash 

<£ To Wastewater 

Treatment 

A 

Radical Initiator -

Mixing 

Tank 

<S> 

Water 

Dispersing Agent 

Suspension Stabilizer 

(Rubber) 

(Blowing Agent) 

Denotes potential location 

of emission source 

4 

, 

• 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Reactor 

© Acid Water 

L-C-® © ® 

Devolatilization 

Extruder^ 

To Wastewater 

Treatment 

To Wastewater 

Treatment 

Polystyrene 

Beads 

Polystyrene 

Pellets 

Figure 6. Polystyrene Production by Suspension Polymerization1 
o 

Styrene -

Steam 

X 

Monomer 

Wash 

© 

InitiatorFugitives from 

overall process 

.To Wastewater 

Treatment 

© 

Prepolymerization 

Reactor 

Low Molecular 

-*- Weight Polymer 

to Landfill 

i 

Extruder. 

Polystyrene 

Pellets 

Secondary sources 

Storage and 

loading losses 

Denotes potential location 

of emission source 

Figure 7. Polystyrene Production by Mass Polymerization' 
P.62 

reactor equipped with a reflux condenser operating under reduced 

pressure (Step 2). Reaction temperature is controlled by 

removing some of the monomer vapor, condensing it, and then 

returning the liquid monomer to the reactor. Polymerization may 

be initiated either thermally or through the use of chemical 

initiators. In this reactor monomer conversion proceeds to 25 to 

35 percent. The polymer melt is then fed through a series of 

stirred reflux reactors (Step 3). The reaction temperature is 

continually raised to promote polymerization and reduce the 

viscosity of the polymer mass. Final temperatures typically 

range from 150 to 200"C. The polymer melt is transferred to a 

static devolatilizer (Step 4) where unreacted monomer and low 

molecular weight polymers are flashed off distilled and recycled 

(Step 5). The stripped polymer is fed through a vent extruder 

and pelletized (Step 6).3 

Solution Process-— 

A block diagram of the polystyrene solution process is 

presented in Figure 8. In this process, polymerization proceeds 

in a solvent medium. In Step l, styrene monomer is steam 

stripped to remove any inhibitors of the polymerization reaction. 

The washed styrene monomer is mixed with a solvent (such as 

ethylbenzene) and an initiator, then fed through a series of 

agitated reactors (Step 2). The initial ethylbenzene 

concentration may range from 5 to 25 percent. Following 

polymerization the polymer mix is sent to a flash tank for the 

removal of unreacted styrene and solvent (Step 3). Recovered 

styrene and solvent are recycled with the reactor feed. The 

purified polymer is fed through an extruder and chopped into 

pellets (Step 4).3 

Emissions 

Typical emission sources at a polystyrene plant include 

process vents, storage tanks, equipment leaks, secondary sources, 

51 
Ol 

M 

StyreneSteam 

Monomer 

Wash 

© 

_^. To Wastewater 

Treatment 

Ethylbenzene 

Initiator 

Rash 

Tank 

®, A 1 

Extruder ® 

Denotes potential location 

of emission source 

Polystyrene 

Pellets 

Fugitives from 

overall process 

Secondary sources 

c 5 

Storage and 

loading losses 

Figure 8. Polystyrene Production bv Solution Polvmrwatinn" 
P.64 

and transfer and handling operations. Styrene may also be 

emitted during accidental or emergency releases.3 

Styrene may be emitted from reactor vents, mixing tanks, 

wash tanks, devolatilizer condenser vents, styrene recovery unit 

condenser vents, and during polymer drying and finishing stages.3 

The monomer storage tank, the mixing/dissolving tanks, and the 

reactor feed tank typically have fixed roofs.4 Emissions from 

these sources are relatively small and are due to normal 

breathing and filling of the tanks.4 Vapor balance use on 

working condensor is the largest styrene emission source in a 

polystyrene plant; however, the quantity of emissions is not 

particularly large.4'* Following the devolatilization step, 

residual styrene monomer in the polymer is typically less than 

one percent.3 The extruder pelletizer vent is potentially the 

second largest styrene emission source.4 

Vent emissions may be controlled by routing the process 

streams to a flare or a blowdown tank.6 Conservation valves can 

be installed on holding and mixing tanks.4 Vapor return lines to 

tank cars or trucks can be installed to reduce styrene losses 

during storage tank filling.4 

Fugitive emissions result from leaks in flanges, valves, 

pumps, open drains, and other equipment components. Control of 

these emissions may be accomplished through a regular inspection 

and maintenance program as well as by equipment modification. 

The mode of operation also influences emissions. Batch 

processes generally have high conversion efficiencies, leaving 

only small amounts of unreacted styrene to be emitted if the 

reactor is purged or opened between batches." In continuous 

processes a lower percentage of styrene is converted to 

polystyrene, and thus larger amounts of unreacted styrene may be 

emitted.' 

53 
P.65 

Facilities using batch processes may manufacture a wide 

variety of polystyrene products. Styrene emissions vary with the 

product grade with higher emissions expected during the 

manufacture of lower molecular weight products.10 Typical 

emission factor ranges suggested by the Chemical Manufacturers 

Association (CMA) for three batch process vents are presented in 

Table 9. 

For plants using the continuous process, a wide range of 

emission rates have been found, depending in part on the type of 

vacuum system used.* The shift from the use of steam eductors to 

vacuum pumps results in lower emission factors.10 Table 9 

presents VOC emission factors given by CMA for the continuous 

polystyrene plants. Emission factors for the same vents based on 

information from other industry sources are also presented in 

Table 9.9 

STYRENE-BUTADIENE COPOLYMER PRODUCTION 

Styrene-butadiene copolymers are composed of monomer units 

of styrene and butadiene. The copolymers may be categorized into 

two general types: styrene-butadiene rubber (SBR) and 

styrene-butadiene latex (S-B latex), based on percent styrene 

composition. However, the exact nomenclature for the different 

types of styrene-butadiene copolymers is often used differently 

between the plastics and rubber industry. 

SBR copolymers contain less than 45 percent styrene and have 

rubber-like qualities. They are characterized by processability, 

heat aging, and abrasion resistance. SBR can be in a solid 

(elastomer) or latex (elastomer emulsion) form. The solid form 

of the copolymer is also known as crumb. 

As the styrene content is increased above 45 percent, 

copolymers become more plastic-like and are in latex form. They 

may be referred to as S-B latex. S-B latex is characterized by 

54 
TABLE 9. EMISSION FACTORS FOR POLYSTYRENE PRODUCTION 

Uncontrolled Emission Rate 

Emission 

Source 

Feed dissolver 

(mixing tank) 

Process (Kg Styrene/ (Lb Styrene/ 

Type Mg Resin) Ton Resin) 

Continuous 0.009 0.018 

Stream 

Composition 

92% styrene* 

7.5% polybutadiene 

1.5% other 

Ref, 

Ol 

Ol 

Reactor heading 

vent 

Devolatilizer 

condenser vent 

Styrene recovery 

unit condenser vent 

Extruder quench 

vent 

Batch 

Batch 

Continuous 

Continuous 

Continuous 

Continuous 

Batch 

Continuous 

Continuous 

0.15-1.35 

0.25-0.75 

0.05-0.06 

0.05-2.96 

0.05-0.06 

0.05-0.13 

0.15-0.30 

0.009-0.01 

0.15 

0.3-2.7 

0.5-1.5 

0.10-0.12 

0.10-5.92 

0.10-0.12 

0.10-0.26 

0.30-0.60 

0.018-0.02 

0.30 

N/Ab 

N/A 

N/A 

21.8% styrene 

78.2% steam 

N/A . 

2.1% styrene 

97.9% steam 

N/A 

N/A 

trace styrene 

99.99% steam 

10 

10 

10 

9 

10 

9 

10 

10 

9 

"It is assumed that numbers do not total due to rounding. 

"Not available. 
P.67 

excellent resistance to water and very good electrical insulation 

qualities. 

Styrene-butadiene copolymers account for 13 percent of 

national styrene consumption.6 SB copolymers are produced by 13 

companies at 23 facilities in 12 states. Elastomer and latex 

production facilities are listed in Tables 10 and 11, 

respectively. The U. S. annual production capacity of SB 

copolymers for 1990 is estimated to be 1,575,691 Mg 

(3474 MM lbs), 61 percent elastomer and 39 percent latex.8 Most 

SBR elastomer is used to manufacture automobile tires and related 

automotive products. In the United States, SBR has the highest 

production rate of all synthetic rubbers. However, due" to the 

longer life of tires and the use of smaller tires, U. S. demand 

for SBR is declining. Other automotive uses of SBR include 

belts, hoses, gaskets, and seals. Non-automotive uses of SBR 

include cable insulation, hoses, tubes, conveyor belts, floor 

tiles, shoe soles, adhesives, and sporting goods. Over 

80 percent of styrene-butadiene latexes are used in the 

carpet/upholstery backing and paper coating industries.3 

Process Description 

Styrene-butadiene elastomer is manufactured by two types of 

polymerization processes: (1) the emulsion process, in which the 

monomers are dispersed in water, and (2) the solution process, in 

which the monomers are dissolved in a solvent. The emulsion 

process is more commonly used. Styrene-butadiene latex is 

produced by the emulsion process in a similar manner to SBR, 

except that the emulsion breaking (coagulation) and drying steps 

are omitted. 

Emulsion Process— 

A flow diagram of the emulsion process for SBR elastomer 

production is shown in Figure 9. In Step l, fresh styrene and 

56 
P.68 

TABLE 10 . SBR ELASTOMER PRODUCTION FACILITIES 

Company 

Ameripol 

Copolymer 

Firestone 

General Tire 

Goodyear 

Location 

Port Neches, TX 

Baton Rouge, LA 

Lake Charles, LA 

Odessa, TX 

Beaumont, TX 

Houston, TX 

TOTAL 

Annual 

(Mg/yr) 

336,000 

125,000 

120,000 

90,000 

20,000* 

305.000 

996,000 

Capacity 

(MM Ib/yr) 

741 

276 

265 

198 

44 

672 

2,196 

"For captive use. 

NOTE: This listing is subject to change as market conditions 

change, facility ownership changes, plants are closed down. etc. 

The reader should verify the existence of particular facilities 

by consulting current listings and/or the plants themselves. The, 

level of styrene emissions from any given facility is a function 

of variables such as Capacity, throughput, and control measures, 

and should be determined through direct contact with plant 

personnel. These operating plants and locations were current as 

of January 1990. 

Source: Reference 5. 

57 
P.69 

TABLE 11. STYRENE-BUTADIENE LATEX PRODUCTION FACILITIES 

Company 

SBR LATEX* 

BASF 

B.F. Goodrich 

GenCorp 

Goodyear 

S-B LATEX* 

BASF 

B.F. Goodrich 

Colloids 

Dow Chemical 

Location 

Chattanooga, TN 

Akron, OH 

Mogadore, OH 

Akron, OH 

Calhoun, GA 

Houston, TX 

TOTAL 

Chattanooga, TN 

Monaca, PA 

Akron, OH 

Gastonia, GA 

Dalton, GA 

Annual Capacity 

(Mg/yr) (MM 

9,030 

907" 

6,804b 

3,175° 

5,443b 

22.680 

68,039 

49,895 

24,948 

907 

15,876 

181,437 

lb/yr) 

64 

2 

15 

7 

12 

50 

150 

110 

55 

2 

35 

400 

GenCorp 

Goodyear 

Reichhold 

W.R. Grace 

Unocal 

Freeport, TX 

Gales Ferry, CT 

Midland, MI 

Pittsburg, CA 

Mogadore, OH 

Calhoun, GA 

Cheswold, DE 

Kensington, GA 

Owensburg, KY 

Charlotte, NC 

La Mirada, CA 

TOTAL 

84, 

39, 

69, 

4, 

27, 

12, 

511, 

,822 

r916 

r853 

,536 

,216 

,247 

,652* 

187 

88 

154 

10 

60 

27 

1,128 

*<45% styrene ... , . 

"Capacity includes s-b-vinylpryidine latex. 

Capacity is all s-b-vinylpyridine latex. 

d>45% styrene ^ .. 

•Numbers do not total due to rounding. 

NOTE* This listing is subject to change as market conditions 

chanae facilitv ownership changes, plants are closed down, etc. 

T I S reader snoHd verify the existence of particular facilities 

bv consulting current listings and/or the plants themselves. The 

level of styrene emission from any given facility is a function 

of variables such as capacity, throughput and control measures, 

and should be determined through the direct contact with plant 

personnel. These operating plants and locations were current as 

of January 1990. 

Source: Reference 5. 

58 
Styrene, 

Butadiene 

Recycled Monomers 

Ol 

vo 

© 

Monomer 

Wash © 

© 

Reactors 

Activator, 

Modifiers, 

Soap Solution, 

Catalyst, 

Water 

Denotes potential location 

of emission source 

© 

© 

Monomer 

Recovery ® 

Shortstop 

Antioxidant 

© 

Acid-brine 

Blending 

® 

Coagulation 

Washing and 

Drying 

S-B/SBR 

•» Latex 

SBR 

Elastomer 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 9. S-B/SBR Production by Emulsion Polymerization11 
P.71 

butadiene monomers are washed to remove inhibitors which may have 

been added to prevent premature polymerization. The washed 

monomers are mixed with recycled monomers, modifiers, activators, 

soap solution (emulsifier), and catalyst and charged into a 

j polymerization reactor (Step 2). A typical recipe for emulsion 

i SBR is presented in Table 12. Polymerization proceeds in a 

\ stepwise fashion through a chain of reactors that allow the 

facility a high degree of flexibility in producing different 

grades of SBR. Either a hot (50°C) or a cold (4*C) process may 

be used. The reaction is normally carried out to a 60 percent 

monomer conversion after which a shortstop solution is added to 

prevent further polymerization. The latex reaction mixture is 

sent to a vacuum flash tank for recovery of unreacted-butadiene 

and then to a steam stripping unit for the recovery of unreacted 

styrene (Step 3). After the monomer is removed, the latex may 

take one of two routes. In one route, SBR elastomer is formed 

through emulsion breaking and drying steps. The stripped latex 

is transferred to a blending and storage tank where an 

antioxidant is added to prevent the polymer from reacting with 

oxygen or ozone (Step 4). The latex stream is then pumped into 

coagulation tanks where the emulsion is broken (Step 5). An 

acid-brine mixture (aluminum sulfate) is added which causes the 

rubber (known as crumb) to precipitate out. The rubber copolymer 

is then sent to a washing and drying section (Step 6) and pressed 

into bales.11'

12 

The second route, which produces styrene butadiene latex as 

the end product, includes the same steps as the elastomer 

production except for the latex coagulation and final rinsing, 

drying and baling. However, in some instances the latex 

polymerization reaction may be continued to a 98 or 99 percent 

conversion—as opposed to 60 percent conversion for emulsion 

crumb rubber. Therefore, in these instances, the monomer 

recovery steps are omitted. The latex product is also passed 

60 
P.72 

TABLE 12. TYPICAL RECTPw rwr, TM„ 

KfaCIPE FOR EMULSION SBR 

Components 

Butadiene 

Styrene 

d-Isopropyl Benzene 

Hydroperoxide 

Ferrous Sulfate 

Tert-Dodecyl Mercaptan 

Potassium Pyrophosphate 

Rosin Acid Soap 

Water 

Source: Reference 11. 

-££i2htPercent 

2 5 

1 0 

<0 

<0 

0 . 

0 . 

1 . 

6 3 

. 0 

. 0 

. 1 

. 1 

1 

1 

4 

. 0 

Function 

Monomer 

Monomer 

Catalyst 

Activator 

Modifier 

Buffer 

Emulsifier 

<>l 
P.73 

through a series of screen filters (Step 7) to remove large 

solids before it is sent to the blending tank for storage (Step 

8).1 1 '" 

Solution Process-— 

A flow diagram for the solution process is shown in 

Figure 10. In this process, polymerization takes place in an 

organic solvent medium, usually hexane. Freshly washed (Step 1) 

and recycled styrene and butadiene monomers and the organic 

solvent are pumped through dryers to remove any water (Step 2), 

then blended together to form the mixed feed. The feed may be 

sent to a dryer as well (Step 3) to remove any residual traces of 

water. The mixture is added to the polymerization reactor along 

with a catalyst (Step 4). Polymerization takes place through a 

series of reactors and proceeds to greater than 90 percent 

conversion. A shortstop solution is added to halt further 

polymerization. The reaction product is in the form of rubber 

cement. It is pumped to product storage (Step 5) where it is 

washed to remove catalyst and then an antioxidant and other 

desired chemicals such as oils and fillers are added. The rubber 

cement is pumped to a coagulator (Step 6) where the rubber is 

precipitated in crumb form. Unreacted monomers and solvent are 

recovered by steam stripping. The stripped rubber cement slurry 

is sent to a washing and drying section (Step 7) where it is 

separated, washed, and then passed through an extruder for 

dewatering and drying. The dried rubber is baled and stored."••" 

Emissions 

The emission sources at an SB copolymer facility are typical 

of those common to chemical production facilities: process 

vents, open process equipment, equipment leaks, storage tanks and 

transfer operations and secondary emissions from the handling and 

disposal of wastes. Styrene may also be emitted during 

accidental or emergency releases. 

62 
Monomer 

Wash © 

CJ 

© 

Monomer 

Drying 

Recycled Monomers and Solvent 

© © 

Feed Drying 

Stripper 

Solvent 

© 

Reactors 

Catalyst 

© 

Rubber Cement 

Wash 

Shortstop 

Antioxidant, 

Oils, 

Fillers 

© 

Coagulation and 

Steam Stripping 

M 

Washing and 

Drying 

SBR 

-*- Elastomer 

Denotes potential location 

of emission source 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 10. SBrt Production by Solution Polymerization 

11 
P.75 

Emissions from process vents and open equipment occur from 

reactors, recovery columns, blend and coagulation tanks, filter 

screens, dryers and other process vessels. They may occur 

continuously (from a continuous process) or intermittently (from 

a batch process). Polymerization reactors for both emulsion and 

solution processes are normally sealed using rupture discs, with 

venting to a flare during rare, extreme upset conditions. Most 

of the styrene emitted during the emulsion crumb process occurs 

by evaporation from open blend and coagulation tanks and from 

dryer vents. An estimated 78 percent of total VOC emissions 

(mostly styrene) from the emulsion crumb process are emitted 

during the copolymer drying steps.14 An emission factor for the 

drying step in SBR emulsion polymerization is given in Table 13. 

Emission data for other process sources are not available.15 In 

the SB latex production process, the latex is stripped of 

unreacted monomers and passed through shaker screens to remove 

large agglomerated solids. These screens are open to the 

atmosphere, but emissions are estimated to be very low. 

Concentrations of 25 ppm styrene (and 39 ppm butadiene) have been 

measured above the screens, but the air flow rate could not be 

determined.ia 

To control process vent emissions, the process streams can 

be routed to a flare or blowdown tank. Recovered styrene 

emissions from the vacuum distillation column are recycled with 

the reactor feed stream. Where feasible, open equipment may be 

enclosed.6 

Sources of fugitive emissions are listed in Section 4. Also 

provided is a description of the procedure for estimating 

emissions and a table of control options and efficiencies. 

At these facilities the major source of air emissions of 

styrene occurs from styrene transfer during the unloading of 

trucks, tank cars and barges and the filling of the monomer 

storage tanks. No SB copolymer facilities are known to have 

64 
P.76 

installed control devices to reduce or capture these emissions.* 

Losses of styrene from storage tanks also occur due to normal 

tank breathing processes. Uncontrolled emission factors for 

breathing and fugitive losses of styrene from storage tanks are 

presented in Table 13." 

STYRENE-ACRYLONITRILE PRODUCTION 

Styrene-acrylonitrile copolymers are noncrystalline, linear 

resins. They are characterized by good hardness, rigidity, 

dimensional stability, high heat deflection temperatures, and 

chemical resistance.1 Acrylonitrile provides the chemical 

resistance and heat stability, and styrene provides rigidity and 

processing ease. A diversity of SAN specialty grades, including 

UV-stabilized, antistat, barrier, and weatherable grades are 

available.17 The styrene content of SAN ranges from 65 to 

85 percent.6'

17'18 

The majority of SAN manufactured is used captively to 

produce acrylonitrile-butadiene-styrene resins. SAN also has a 

wide range of applications in the automotive, housewares, 

electronics, appliances, and packaging marketing areas. SAN is 

used in automotive trim, marine instruments, tractor components, 

coffee filter funnels, instrument panels on appliances and 

automobiles, boat hulls, swimming pool components, cassette 

parts, syringes, dentures, toothbrush handles, blender bowls, and 

vacuum cleaner parts. Most of the SAN sold in the United States 

is used for injection molding as a replacement for polystyrene.19 

Only two companies produce SAN exclusively for sale on the 

market. These facilities and their annual capacities are listed 

in Table 14. SAN is also produced at all ABS facilities, as a 

step in the manufacture of ABS.5 Less than four percent of 

styrene production in the United States is used in the 

manufacture of SAN for direct sale.20 

65 
TABLE 13. EMISSION FACTORS FOR STYRENE-BUTADIENE PRODUCTION 

Emission Rate 

Industrial 

Process 

Emission 

Source 

(Kg Styrene/ 

Mg Resin) 

(Lb Styrene/ 

Ton Resin) 

Control 

Status 

SBR-emulsion Drying 0.6 1.2 Uncontrolled 

SBR-emulsion 

SBR-emulsion/ 

solution 

Storage tank 

(fugitive) 

Storage tank 

(breathing) 

0.4 

0.02 

0.8 

0.04 

Uncontrolled 

Uncontrolled 

<f> 

Source: Reference 12. 

^ i 

^ i 
P.78 

TABLE 14. STYRENE-ACRYLONITRILE PRODUCTION FACILITIES 

Company* 

Dow 

Monsanto 

Location 

Midland, MI 

Addyston, OH 

TOTAL 

Annual 

(Mg/yr) 

31,751 

22.679 

54,431b 

Capacity 

(MM lb/yr) 

70 

50 

120 

'Only those producers who manufacture SAN for sale on the 

merchant market are listed. All ABS resins producers have SAN 

resin production capacity. 

"Numbers do not total due to rounding. 

NOTE: This listing is subject to change as market conditions 

change, facility ownership changes, plants are closed down, etc. 

The reader should verify the existence of particular facilities 

by consulting current listings and/or the plants themselves. The 

level of styrene emissions from any given facility is a function 

of variables such as capacity, throughput, and control measures, 

and should be determined through direct contact with plant 

personnel. These operating plants and locations were current as 

of January 1990. 

Source: Reference 5. 

67 
P.79 

Process Descriptions 

SAN resins may be produced by emulsion, suspension, or 

continuous mass polymerization. The majority of SAN for captive 

use is produced using emulsion polymerization. SAN for sale in 

the marketplace is most often produced by mass polymerization.31 

Emulsion Process— 

SAN production by emulsion polymerization, shown in 

Figure 11, may be conducted in either a batch or a continuous 

mode.2'

11'18 The batch process is more commonly used»_20_ In both 

processes, styrene and acrylonitrile monomers are pumped into a 

monomer-makeup tank along with recovered acrylonitrile and 

chemical additives (Step 1). The monomer mix is fed into the 

polymerization reactor with emulsifier, initiator, chain-transfer 

agent and deionized water (Step 2). Copolymerization is carried 

out in the temperature range of 70-100°C (160-212°F) and proceeds 

to 90-98 percent conversion.21 The polymerization temperature 

may be reduced to as low as 38°C (100°F) if redox catalysis 

systems are used. After a suitable retention time in the 

reactor, the SAN copolymer melt (latex) is pumped to a steam 

stripper for recovery of unreacted monomers (Step 3). The 

copolymer latex may be used directly in the production of ABS 

resin, or it may be sent to a coagulation and flocculation 

section (Step 4). The polymer is filtered (Step 5) then washed, 

and dried (Step 6) to produce the solid SAN copolymer.2 Dyes, 

antioxidants and other additives may be mechanically blended into 

the copolymer using extruders and rolling mills (Step 7). 

Polymer sheets from these operations are then pelletized and 

packaged. 

68 
VO 

Recycled Monomers 

© © 

Monomer 

Make-Up © 

Polymerization 

Rleacto < r 

© 

Styrene, 

Acrylonitrile, 

Additives 

Emulsifier, 

Initiator, 

Chain Transfer Agent, 

Water 

© 

Steam 

Stripper © 

© 

Coagulation, 

Flocculatkwi 

© 

ABS Production 

Filters 

© 

Washing and 

Drying 

® 

© 

3lendlng, Milling, 

Compounding 

© 

Denotes potential location 

of emission source 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 11. Production of SAN by Emulsion Polymerization21 
P.81 

Suspension Process— 

SAN production by suspension polymerization may be conducted 

in either batch or continuous mode.2'

11'18 A block flow diagram 

for the suspension process is given in Figure 12. Styrene and 

acrylonitrile monomers are fed into a pressure reactor and 

mechanically dispersed in water containing catalysts and 

suspending agents (Step 1). The water functions to remove heat 

and control particle size. Equal amounts of monomer and water 

are used.19 While suspended by agitation, the monomer droplets 

copolymerize forming insoluble beads of polymer. The temperature 

of the polymerization reactor ranges from 60-150°C (140-300°F). 

A monomer conversion of 95 percent is normally achieved. The 

polymer slurry is pumped to a centrifuge for washing and 

dewatering (Step 2). The polymer is sent to a flash tank and 

steam or vacuum stripper' for recovery of unreacted monomers 

(Step 3). The solid and liquid phases of the polymer slurry are 

separated by centrifugation and/or filtration (Step 4). The 

solid phase is then dried in a rotary dryer (Step 5). The dried 

SAN is finished by mechanically blending in dyes, antioxidants 

and other additives. The polymer sheets are then pelletized and 

packaged (Step 6).7'

8 This suspension process is simpler than the 

emulsion process as no coagulation and flocculation steps are 

required. 

Continuous Mass Process— 

The continuous mass process, shown in Figure 13, is a selfcontained system that does not require emulsifiers, suspending 

agents, salts, or water. Solvents are used to control the 

viscosity. In Step one, styrene and acrylonitrile monomers are 

heated together with modifier-solvent and pumped continuously 

into the agitated polymerization reactor maintained at about 

275 kPa (40 psia) and 100-200'c (212-390°F). Catalyst is added 

and reaction 'proceeds to 20 percent conversion. The polymer is 

passed through a series of devolatilizers to remove unreacted 

70 
Styrene, . 

Acrylonitrile 

Recycled Monomers 

L * Polymerization 

Reactor _ 

© 

Water, 

Catalysts, 

Suspending Agents 

© 

Washing and 

Dewatering 

© 

© 

Flash Tank 

and Stripper 

© 

Filters 

© 

Dryer 

© 

^lending, MilllngJ 

Compounding 

© 

Denotes potential location 

of emission source 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 12. Production of SAN by Suspension Polymerization21 
NJ 

Styrene, 

Acrylonitrile, 

Modifer-Solvent 

Recycled Monomers and 

Modifier-Solvent 

© 

Polymerization 

Reactor 

© 

Catalyst 

0 

Devolatilizers 

© 

0 

Blending, Milling, 

Compounding 

© 

Denotes potential location 

of emission source 

FugKrves'from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 13. Production of SAN by Continuous Mass Polymerization 

21 
P.84 

monomers and' modifier-solvent (Step 2). Devolatilization occurs 

under vacuum at a temperature ranging from 120-260°C (248-500°F). 

Inerts, unreacted monomers and modifier-solvent are removed 

overhead from the devolatilizers. The overheads are the 

condensed and passed through a refrigerated styrene scrubber to 

recover monomers and modifier-solvent which are recycled to the 

feed tanks. The bottoms from the final devolatilizer are almost 

pure polymer melt. The polymer melt is pumped through an 

extruder, cooled and chopped into pellets (Step 3).2,11,ia 

EjiH salons 

Facilities manufacturing SAN emit styrene from process 

equipment vents, open process equipment, equipment leaks, storage 

tank vents, secondary sources, and transfer and handling 

operations. No emissions data for any of these sources are 

available. 

Process equipment sources include monomer make-up tanks, 

polymerization reactors, monomer strippers, devolatilizers, 

coagulation/flocculation stages, dewatering/drying stages, and 

blending/compounding operations. The emissions will vary 

according to the type of polymerization process used and the 

exact monomer mix. 

As described under styrene-butadiene copolymer production, 

process vent emissions may be controlled by routing the streams 

to a flare or blowdown. Currently, neither SAN facility has 

controls to capture or prevent styrene emissions from transfer 

operations. 

ACRYLONITRILE-BUTADIENE-STYRENE COPOLYMER PRODUCTION 

Acrylonitrile-butadiene-styrene resins are produced by 

grafting styrene-acrylonitrile copolymer onto a rubber and then 

blending the grafted rubber with SAN.23 Polybutadiene is 

72 
P.85 

monomers and modifier-solvent (Step 2). Devolatilization occurs 

under vacuum at a temperature ranging from 120-260°C (248-500°F). 

Inerts, unreacted monomers and modifier-solvent are removed 

overhead from the devolatilizers. The overheads are the 

condensed and passed through a refrigerated styrene scrubber to 

recover monomers and modifier-solvent which are recycled to the 

feed tanks. The bottoms from the final devolatilizer are almost 

pure polymer melt. The polymer melt is pumped through an 

extruder, cooled and chopped into pellets (Step 2) A'11'" 

Emissions 

Facilities manufacturing SAN emit styrene from process 

equipment vents, open process equipment, equipment leaks, storage 

tank vents, secondary sources, and transfer and handling 

operations. No emissions data for any of these sources are 

available. 

Process equipment sources include monomer make-up tanks, 

polymerization reactors, monomer strippers, devolatilizers, 

coagulation/flocculation stages, dewatering/drying stages, and 

blending/compounding operations. The emissions will vary 

according to the type of polymerization process used and the 

exact monomer mix. 

As described under styrene-butadiene copolymer production, 

process vent emissions may be controlled by routing the streams 

to a flare or blowdown. Currently, neither SAN facility has 

controls to capture or prevent styrene emissions from transfer 

operations. 

ACRYLONITRILE-BUTADIENE-STYRENE COPOLYMER PRODUCTION 

Acrylonitrile-butadiene-styrene resins are produced by 

grafting styrene-acrylonitrile copolymer onto a rubber and then 

blending the grafted rubber with SAN.23 Polybutadiene is 

normally used as the backbone or substrate rubber, but nitrile 

73 
P.86 

rubbers and SBR are also used. The resulting polymer has three 

phases: continuous matrix of SAN, dispersed phase of 

polybutadiene or other rubber, and boundary layer of SAN graft.22 

The SAN grafted rubber provides adhesion between SAN and the 

rubber which would have been incompatible. 

ABS possesses the useful properties of SAN, such as rigidity 

and resistance to chemicals and solvents, while the rubber 

additive imparts impact resistance.2 ABS resins are produced 

with a wide range of properties that are tailored to specific 

applications. The differences in application are achieved by 

changing the relative concentrations of the three monomers and by 

using additives. Over 75 grades of ABS are available, including 

glass reinforced, UV-resistant, flame retardant, foamable, and 

electroplating grades.a3'

24'2S The resins are marketed in powder 

form or as natural and precolored pellets.32 

ABS resins are used to make plastic components for a variety 

of products such as automotive parts, pipes and fittings, 

appliances, telephones, business machines, toys and sporting 

goods. The major use for ABS is in the automotive industry, 

where the resins are injection molded to make interior trim 

components, consoles, instrument panel trim grills and wheel 

covers. 

Currently ABS resins are produced by three companies at ten 

locations in eight States. These facilities and their production 

capacities are listed in Table 15. These ten facilities also 

produce SAN as a step in the manufacture of ABS. Industry-wide 

ABS capacity for 1990 is about 790,158 Mg/yr (1742 MM lbs).5 

Manufacture of ABS and SAN resins consumes 9 percent of u. S. 

styrene production.6 

74 
P.87 

TABLE 15. ACRYLONITRILE-BUTADIENE-STYRENE PRODUCTION FACILITIES 

Company 

Diamond Polymers 

Dow 

General Electric 

Monsanto 

Location 

Akron, OH 

Gales Ferry, CT 

Ironton, OH 

Midland, MI 

Torrance, CA 

Bay St. Louis, MS 

Ottawa, IL 

Washington, WV 

Addyston, OH 

Muscatine, IA 

TOTAL 

Annual 

(Mg/yr) 

9,979 

27,215 

36,287 

68,039 

18,144 

95,254 

136,078 

158,757 

145,150 

95.254 

790,158 

Capacity 

(MM lb/yr) 

22 

60 

80 

150 

40 

210 

300 

350 

320 

210 

1,742 

NOTE: This listing is subject to change as market conditions 

change, facility ownership changes, plants are closed down{ etc. 

The reader should verify the existence of particular facilities 

by consulting current listings and/or the plants themselves. The 

level of styrene emissions from any given facility is a function 

of variables such as capacity, throughput, and control measures, 

and should be determined through direct contact with plant 

personnel. These operating plants and locations were current as 

of January 1990. 

Source: Reference 5. 

75 
P.88 

Process Descriptions 

ABS resins may be synthesized by emulsion, suspension, and 

continuous mass (bulk) polymerization. The majority of 

production is by batch emulsion. Specialized resins are produced 

by suspension polymerization. Emulsion and suspension 

polymerizations are based on an aqueous-phase reaction. In 

contrast, the continuous mass process, the newest technology, 

does not proceed in water. Therefore, dewatering and polymer 

drying are not required and wastewater treatment is minimized.23 

Emulsion Process— - -. _ 

A block diagram showing two routes by which ABS is produced 

using the emulsion process is presented in Figure 14. This 

process is referred to as the ABS/SAN process because SAN is 

prepared in a side step and mixed with graft ABS. 

The emulsion process involves three distinct 

polymerizations: 

polymerization of butadiene to form polybutadiene; 

grafting of styrene and acrylonitrile monomers to the 

polybutadiene substrate; and 

copolymerization of styrene-acrylonitrile. 

Butadiene monomer is converted to polybutadiene latex 

(Step l) and then pumped into the ABS reactor with styrene, 

acrylonitrile, emulsifiers and initiators (Step 2). The styrene 

and acrylonitrile monomers are grafted to the polybutadiene latex 

substrate in either a batch or continuous process. Reaction 

conversion is 90 to 95 percent. Vapors from the reactor are 

usually vented to an acrylonitrile absorber. The absorber 

emissions are usually vented to the atmosphere or incinerated. 

The graft ABS is then transferred to a coagulator (Step 3). SAN 

76 
Polybutadiene 

Reactor ~ . © 

ABS Latex 

Reactor-. 

© 

Styrene 

Acryonitrile, 

Emulsifiers and 

Initiators 

Stryene, 

Acrylonitrile, 

Emulsifiers, 

Catalysts, Water 

0 

Coagulator. 

?—T 

SAN 

SAN Resin 

Reactor 

© (8 

Screei fe 

Steam, 

Antioxidant, 

Coagulant 

Coagulator 

© 

Centrifuge 

© 

Additives, 

Antioxidants, • 

Dyes 

Alternative SAN Path 

0 

Vacuum 

Filtration © 

Mechanical 

Blending 

© 

•> Dewaterlng 

< $ 

Packaging 

© 

Denotes potential location 

of emission source 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 14. Production of ABS/SAN by Emulsion Polymerization n 
P.90 

copolymer is prepared in a separate side step (Step 8) (see 

process descriptions under SAN copolymers in this section). The 

graft ABS and the SAN may be mixed together at either of two 

points in the emulsion process. The SAN latex may added to the 

graft ABS latex in the ABS coagulator (Step 3). The agglomerated 

polymer is dewatered by screening (Step 4), centrifuging 

(Step 5), and vacuum filtration (Step 6). No drying step is 

required. However, some facilities employ a dryer in place of 

the centrifuge and vacuum filter. The ABS is sent to a finishing 

section where dyes, antioxidants, and other additives are 

mechanically blended in (Step 7). Alternatively, the SAN latex 

may be pumped into an SAN coagulator (Step 8) and sent, to a 

dewatering section (Step 10) separately. The solid SAN is then 

mechanically mixed with solid graft ABS at the finishing stage 

(Step 7). The polymer sheets are cut into pellets and packaged 

(Step ll).2-"'" 

In a third route (not shown) SAN graft and styreneacrylonitrile copolymerization occur in the same reaction vessel. 

The resulting ABS latex is coagulated, washed, filtered and 

dried. 

Suspension Process— 

A block flow diagram of the suspension ABS process is shown 

in Figure 15. This process begins with polybutadiene rubber 

which is so lightly cross linked that it is soluble in the 

acrylonitrile and styrene monomers. The polybutadiene is first 

dissolved in styrene and acrylonitrile monomers to produce a 

solution free of crosslinked rubber gels (Step 1). The solution 

is pumped into a prepolymerizer where a free-radical initiator is 

added along with chain-transfer agents in a prepolymerizer 

(Step 2). After 25 to 35 percent monomer conversion, the polymer 

syrup is transferred to a suspension reactor where it is 

dispersed in water by agitation (Step 3). 

78 
Styrene, 

Acrylonitrile 

10 

© 0 

Rubber 

Dissotver © 

Polybutadiene 

Rubber 

Pre 

Polymerlzer 

© 

Initiators and 

Chain Transfer Agents 

© 

Suspension 

Reactor 

© 

Suspending Agent, 

Water 

© 

Dewatering 

© 

© B 

J 

Dryer 

© 

Product 

Storage © 

Denotes potential location 

of emission source 

\ 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 15. Production of ABS by Suspension Polymerization 

11 
P.92 

After achieving the desired monomer conversion, the products 

are transferred to a washing/dewatering system (Step 4), usually 

a continuous centrifuge. The polymer beads are then sent to a 

hot air dryer (Step 5). The dried finished beads are transferred 

to product storage (Step 6).2'"'18 

Continuous Mass Process—'• 

A block flow diagram for the continuous mass ABS process is 

shown in Figure 16." Unlike emulsion and suspension 

polymerization, this polymerization process does not proceed in 

water. A lightly cross-linked, monomer-soluble form of 

polybutadiene is dissolved in styrene and acrylonitrile monomers, 

along with initiators and modifiers (Step 1). The mixed feed is 

pumped into a prepolymerizer, in which a conversion reaction 

causes the ABS rubber to precipitate out of solution (Step 2). 

When monomer conversion reaches about 30 percent, the resulting 

syrup is transferred to the bulk polymerizer where monomer 

conversion is continued to between 50 to 80 percent (Step 3). 

The polymer melt is sent to a devolatizer (Step 4) where 

unreacted monomer is removed under vacuum. The monomer vapors 

are condensed and recycled to the prepolymerizer. The ABS 

polymer is then passed through an extruder, cooled in a water 

bath (Step 5), and chopped into pellets (Step 6).2'

11'18 

Emissions 

Information is available on acrylonitrile and butadiene 

emissions from 10 ABS production facilities. Although styrene 

emissions were not reported separately by any of the facilities, 

three facilities listed "other VOC" emission estimates, of which 

the major component is likely to be styrene. These VOC emissions 

were attributed to process vents from polymerization reactors, 

coagulation/washing steps, dewatering, intermediate process 

tanks, and compounding.23 Significant styrene emissions result 

primarily from unloading styrene from tank trucks and barges and 

80 
00 

Acrylonitrile, 

Initiators, 

Styrene Modifiers 

Polybutadiene 

Rubber 

0 

Rubber 

Dissolver © 

© 

Prepolymerizer 

© 

Monomer 

Recycle 

Condensor © 

Bulk 

Polymarker 

© 

A 

Devolatilizer 

© 

© 

Extruder/ 

Water Bath 

© 

Pellet izer 

© 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses Denotes potential location 

of emission source 

§ 

Figure 16. Production of ABS by Continuous Mass Polymerization *' 
P.94 

filling the storage tank.6 In addition, some emissions are 

possible from secondary sources and emergency and accidental 

releases. Insufficient information is available to develop 

emission factors for fugitives or process emission sources. 

The emission points vary depending upon the type of 

polymerization process used. The emulsion process has the 

highest emissions while the continuous mass process has 

inherently low emissions. In addition, styrene emissions may 

vary from plant to plant depending on product mix. 

Manufacturers of ABS resins have taken two basic-approaches 

to control some of the AN process vents: high monomer conversion 

technology (HMCT) and thermal oxidation. These techniques would 

also control styrene emissions. The high monomer conversion is 

achieved using a second reactor the same size as the first 

reactor where conversion is increased to around 98 percent. The 

HMCT requires that the second reactor and an absorber be 

installed at the polymer filter step. Thermal oxidation is 

applicable to all types of ABS processes. In this approach 

emission vents are tied into one or more combustion devices. 

These devices may be parts of steam generators, incinerators or 

flares.23 

UNSATURATED POLYESTER RESIN PRODUCTION 

Thermoset polyester resins are complex polymers resulting 

from the cross-linking reaction of a liquid unsaturated polyester 

with a vinyl type monomer, most often styrene. The unsaturated 

polyester is formed from the condensation reaction of an 

unsaturated dibasic acid or anhydride, a saturated dibasic acid 

or anhydride, and a polyfunctional alcohol. Table 16 lists the 

most common compounds used for each component of the polyester 

"backbone," along with the principal cross-linking monomer 

styrene. The chemical reactions that form both the unsaturated 

82 
P.95 

TABLE 16. TYPICAL COMPONENTS USED TO FORM 

UNSATURATED POLYESTER RESINS 

Unsaturated 

Acids 

Saturated 

Acids 

Polyfunctional 

Alcohols 

Cross-Linked 

Agent 

(Monomer) 

Maleic 

anhydride 

Fumaric acid 

Phthalic 

anhydride 

Isophthalic 

acid 

Adipic acid 

Propylene 

glycol 

Ethylene glycol 

Diethylene 

glycol 

Dipropylene 

glycol 

Neopentyl 

glycol 

Pentaerythritol 

Styrene 

Source: Reference 27. 

83 
P.96 

.i-

| polyester and the cross-linked polyester resin are shown in 

] Figure 17.27 

In order to be used in the fabrication of products, the 

\ liquid resin must be mixed with a catalyst to initiate 

: polymerization into a solid thermoset. Catalyst concentrations 

generally range from 1 to 2 percent by original weight of resin; 

within certain limits, the higher the catalyst concentration, the 

faster the cross-linking reaction proceeds. Common catalysts are 

organic peroxides, typically methyl ethyl ketone peroxide or 

benzoyl peroxide. Resins may contain inhibitors, to avoid self 

curing during resin storage, and promoters, to allow 

polymerization to occur at lower temperatures.27 

Unsaturated polyester resins (UPR) are produced by 23 

companies at 56 locations in the United States as shown in 

Table 17. Production capacity for these facilities was not found 

in the literature. Although styrene is not the only monomer that 

may be used as a cross-linking agent, it is the most common. In 

1988, total UPR production in the United States was 768,852 Mg 

(1695 MM lbs).6 UPR is a thermoset resin used in construction 

(tubs and showers), marine and marine accessories (boats, boat 

accessories), casting (cultured marble and onyx), transportation 

(distributor caps, auto body parts), consumer goods (appliances), 

gel coatings, surface protective coatings, bonding/adhesives, 

electrical components, and business machines. 

Process Description 

Unsaturated polyester resins can be produced by a fusion or 

a solvent process. There is no published information on their 

relative capacities, however. In the fusion process, an inert 

gas (typically nitrogen) is used to remove water that is 

generated during the production process. The solvent process 

uses azeotropic distillation.4 Both of these are batch 

processes. The fusion process consists of the reacting 

84 
Reaction 1 - Unsaturated Polyester 

o o 

\\ // 

c—o-c _ 

1 1 o o 

n • HC = . CH + 2n • HOH.C —CHOH + n • C — O — C -

\ / 

Malelc Anhydride Ethylene Glycol 

Phthatlc Anhydride 

— C C — 

\ / 

O 

II 

O — CHj— CHy- O — C 

I 

HC 

C — O —CHj—CH^— O 

I 

CH 

+ 2n • HjO 

Unsaturated Polyester 

03 Reaction 2 - Polyester Resin 

O

Unsaturated 

+ Polyester 

Styrene 

o o 0 

II I II II 

( —CHj—CHj— O — C —CH—CH— C — O — CHr-CH — O — C 

I 

H — C — H 

I 

H —C -

II — / 3 — C — O — ) n 

( - O — C — { 3 — C — O — CHj-CHj— O — C —CH—CH— C — O —CHj—CHj- ) n 

II I 

O H—C—H 

H—C— ff ^ Cross-finked 

• **& Polyester Resin 

Figure 17. Typical Reaction for Unsaturated Polyester and 

Polyester Resin Formation 27 

CD 
P.98 

TABLE 17. PRODUCERS OF UNSATURATED POLYESTER RESINS 

Facility Location(s) 

The Alpha Corporation 

American Cyanamid Company 

Aristech Chemical Corporation 

Ashland Chemical Inc. 

Barton Chemical Corporation 

BASF Corporation 

Bayer USA Inc. 

BP America, Inc. 

Cargill, Inc. 

Cook Composites 

Dow Chemical U.S.A. 

Emhart Corporation 

The P.D. George Company 

High J. - Resins Company 

ICI American Holdings, Inc. 

(The Gliden Company) 

Insulating Materials Inc. 

Collierville, TN 

Kathleen, FL 

Perris, CA 

Wallingford, CT 

Bartow, FL 

Colton, CA 

Jacksonville, AR 

Neville Island, PA 

Ashtabula, OH 

Calumet City, IL 

Los Angeles, CA 

Philadelphia, PA 

Bartow, FL 

Chicago, IL 

Detroit, MI 

Houston, TX 

Covington, KY 

Hawthorne; CA 

Atlanta, GA 

Parpentersvilie, IL 

Ennis, TX 

Forest Park, GA 

Lynwood, CA 

Bethlehem, PA 

North Kansas city, MO 

Catham, VA 

Marshall, TX 

Saukville, WI 

Joliet, IL 

Middleton, MA 

St. Louis, MO 

Long Beach, CA 

Columbus, GA 

Reading, PA 

Schenectady, NY 

86 
P.99 

TABLE 17. (Continued) 

Facility Location(s) 

Interplastic Corporation 

The O'Brien Corporation 

Owen's Corning Fiberglas Corp. 

Reichhold Chemicals, Inc. 

Sherex Chemical Company 

Trinova Corporation 

Valspar Corporation 

(McWhorter, Inc., subsidiary) 

Minneapolis, MN 

Pryor, OK 

South Bend, IN 

Anderson, SC 

Valparaiso, IN 

Azusa, CA 

Bridgeville, PA 

Houston, TX 

Jacksonvilie, FL 

Morris, IL 

Oxnard, CA 

Lakeland, FL 

Auburn, ME 

Chicago, IL 

Rochester, PA 

Baltimore, MD 

Carpenstersvilie, IL 

Kankakee, IL 

Los Angeles, CA 

Philadelphia, PA 

Portland, OR 

NOTE: This listing is subject to change as market conditions 

change, facility ownership changes, plants are closed down, etc. 

The reader should verify the existence of particular facilities 

by consulting current listings and/or the plants themselves. 

These operating plants and locations were current as of January 

1990. 

Source: Reference 5. 

87 
P.100 

(polyesterification) and thinning stages (Figure 18). During 

polyesterification, dibasic acids such as maleic and phthalic 

anhydrides, isophthalic acids, and glycols such as ethylene and 

propylene glycol are combined to form a soluble resin. This 

condensation reaction is carried out in an insulated stainless 

steel or glass-lined kettle. The mixture is then heated to about 

200*C and held for 10 to 20 hours, and water (by-product) is 

continuously removed by bubbling an inert gas through the 

mixture.4'

28 When the desired degree of condensation is reached, 

the product is cooled, blended with additives if necessary, and 

transferred to the thinning tank. In the thinning tank, styrene 

monomer is combined with the cooling unsaturated resin from the 

polyesterification tank (Step 2). The final product is then 

transferred to a storage tank (Step 3). 

The solvent process is similar to the fusion process except 

that instead of bubbling an inert gas through the mixture to 

remove water, xylene is added. A xylene-water azeotrope is 

formed. The azeotrope enhances the separation of water vapor 

by-product. The xylene in the condensed azeotrope is separated 

from the water and is recycled using a decanter and two 

receivers. 

Emissions 

The following information is taken directly from a 1979 

report prepared for the U. S. Environmental Protection Agency 

that estimated and ranked VOC emissions for'the plastics 

industry. Data were gathered through literature surveys, 

calculations, site visits, and questionnaire responses.* For UPR 

production (both the fusion and the solvent processes), one 

source of styrene emissions is the thinning tank vent (A). 

Overhead vapors from the thinning operation are usually 

controlled by a cooling-water condensor; otherwise they remain 

uncontrolled. The emission factor developed for the UPR thinning 

tank is shown in Table 18. The authors of Reference 4 estimate 

88 
CO 

vo 

PhthaJlc 

Anhydride 

Maleic 

Anhydride 

Propylene 

Glycol 

Inert Gas 

or Xylene 

Polyesterificatlon 

Reactor 

© 

Water 

Styrene 

Monomer 

Storage 

Product 

Blending 

Tank 

(£) 

Product 

Storage 

<D 

Denotes potential location 

of emission source 

To Drumming or 

Truck Loading 

Fugitives from 

overall process 

Secondary sources 

Storage and 

loading losses 

Figure 18. Unsaturated Polyester Resin Production 
TABLE 18. EMISSION FACTORS FOR STYRENE 

FROM UPR PRODUCTION 

P.2 

Emission 

Source 

Estimated Emission Factor" 

(Kg/Mg Resin) (Lb/Ton Resin) 

Thinning tank 

Blending tank 

Product storage 

Monomer storage 

0.08 

0.05 

0.05 

0.02 

0.16 

0.10 

0.10 

0.04 

"The emission factors are for fusion and solvent processes (while 

reactor is operating). ~ -

Source: References 4 and 28. 

90 
P.3 

that the use of a refrigerated brine condensor on the thinning 

tank vent could reduce emissions by 80 percent. Industry experts 

indicate that this method is no longer practiced and that Thermal 

Oxidation is the preferred method today.2* 

Also shown in Table 18 are styrene emission factors for UPR 

product storage (C) and styrene monomer storage (B). The 

emission factor shown for UPR product storage assumes that the 

tanks are equipped with fixed-roof tanks. Monomer storage tanks 

are also assumed to be equipped with fixed-roof tanks, with a 

50 percent reduction in styrene emissions achievable with 

floating-roof tanks and/or refrigerated vent condensers. 

MISCELLANEOUS STYRENE COPOLYMER PRODUCTION 

In addition to the sources of styrene emissions previously 

discussed, styrene is also used in the production of 

miscellaneous products such as styrene-butadiene-vinylpyridine 

(SBV) latex, methyl methacrylate-butadiene-styrene (MBS) resins, . 

and methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) 

polymer. Table 19 summarizes the location of these facilities 

and their estimated production capacities. 

Available details of the production processes will be 

provided, where known. Often these details are incomplete; 

therefore, readers should contact the facilities directly for the 

most accurate information. No information was found in the 

literature about styrene emissions from these facilities. 

Styrene-Butadiene-Vinylpyridine Latex 

No information on the production process or use of styrenebutadiene-vinylpyridine latex is available. As a copolymer, the 

production is likely to be similar to that of other copolymers. 

91 
TABLE 19. MISCELLANEOUS USES OF STYRENE IN CHEMICAL PRODUCTION 

Company Location 

Ameripol Synpol Port Neches, TX 

Product 

Styrene-butadienevinylpyridine (SBV) 

Latex 

Borg-Warner 

Chemical Co. 

GenCorp 

NJ 

Goodyear 

Goodyear 

Kaneka Texas 

Co. 

Metco America 

Rohm & Haas Co. 

Standard Oil 

Chemical Co. 

Washington, WV 

Mogadore, OH 

Akron, OH 

Calhoun, GA 

Bayport, TX 

Axis, AL 

Louisville, KY 

Lima, OH 

Methyl Methacrylatebutadiene-styrene 

(MBS) Resins" 

SBV Latex 

SBV Latex 

SBV Latex 

MBS Resins 

MBS Resins 

MBS Resins 

Methyl Methacrylate 

acrylonitrilebutadiene-styrene 

(MABS) Polymer 

«n—11 capacity not known. 

b Increased capacity due on-line by 

Source: Reference 11. 

the end of 1987. 

Mode of 

Operation 

Unknown 

Unknown 

Unknown 

Unknown 

Unknown 

Batch 

Unknown 

Batch 

Unknown 

1986 Design 

Capacity 

(Mg/yr) 

(MM 

lb/yr) 

__« 

24,000* 53 

V 
P.5 

I 

Methyl Methacrylate-Butadiene-Styrene Terpolvmers 

Methyl methacrylate-butadiene-styrene terpolymers are 

produced in resin form by four companies at four locations. This 

resin is used as an impact modifier in rigid polyvinyl chloride 

products for applications in packaging, building, and 

construction. Production of MBS terpolymers is achieved using an 

emulsion process in which methyl methacrylate and styrene are 

grafted onto a styrene-butadiene rubber. The product is a twophase polymer." 

Methyl Methacrvlate-AcrYlonitrile-Butadiene-Styrgne Polymers 

Methyl methacrylate-acrylonitrile-butadiene-styrene polymers 

are produced by Standard Oil Company under the trade name Barex®. 

The MABS copolymers are prepared by dissolving or dispersing 

polybutadiene rubber in a mixture of methyl methacrylateacrylonitrile-styrene and butadiene monomer. The graft 

copolymerization is carried out by a bulk or a suspension 

process. The final polymer is two phase, with the continuous 

phase terpolymer of methyl methacrylate, acrylonitrile, and 

styrene grafted onto the dispersed polybutadiene phase.11 

These polymers are used in the plastics industry in 

applications requiring a tough, transparent, highly impactresistant, and thermally formable material. Except for their 

transparency, the MABS polymers are similar to the opaque 

acrylonitrile-butadiene-styrene plastics. The primary function 

of methyl methacrylate is to match the refractive indices of the 

two phases, thereby imparting transparency.11 

93 
P.6 

REFERENCES FOR SECTION 5 

1. Swett, R. M. Polystyrene. Modern Plastics Encyclopedia. 

63:74-78. 1986-1987. 

2. Kirk-Othmer Encyclopedia of Chemical Technology. 3rd 

Edition. Styrene Plastics. John Wiley and Sons. New York, 

New York. Vol. 1, pp. 427-441, Vol. 21, pp. .801-811. 1978. 

3. Industrial Process Profiles for Environmental Use. Chapter 

10 - The Plastics and Resins Production Industry, pp. 74-

93, 465-518, 641-657. 

4. Click, C. N. and D. K. Webber. Polymer Industry Ranking by 

VOC Emissions Reduction That Would Occur From New Source 

Performance Standards. Prepared for U. S. Environmental 

Protection Agency, Research Triangle Park, NorthJ^arolina. 

pp. 187-198, 227, 233-236. 1979. 

5. SRI International. 1990 Directory of Chemical Producers -

U.S.A. Menlo Park, California. 

6. A. T. Kearney. Impact Analysis of the EPA Office of 

Drinking Water Proposal to Regulate Styrene. Styrene 

Information Research Center. 1989. 

7. Chemical Product Synopsis. Polystyrene. April 1988. 

8. U. S. Environmental Protection Agency. Polymer 

Manufacturing Industry - Background Information for Proposed 

Standards. Draft EIS. EPA-450/3-83-019a. U. S. 

Environmental Protection Agency, pp. 3-40 to 3-53. 1985. 

9. U. S. Environmental Protection Agency. Guideline Series -

Control of Volatile Organic Compound Emissions from 

Manufacture of High-Density Polyethylene, Polypropylene, and 

Polystyrene Resins. EPA-450/3-83-008. U. S. Environmental 

Protection Agency, pp. 2-18 to 2-25. 1983. 

10. Letter from J. S. Matey, Chemical Manufacturers Association, 

to E. J. Vincent, U. S. Environmental Protection Agency. 

October 19, 1981. 

11. Buchanan, S. K. Locating and Estimating Air Emissions from 

Sources of 1,3-Butadiene. EPA-450/2-89-021. U. S. 

Environmental Protection Agency, Research Triangle Park, 

North Carolina, pp. 44-45, 71-79. 1989. 

12. Chi, C. T. et al. Source Assessment: Rubber Processing, 

State of the Art. EPA-600/2-78-004J. U. S. Environmental 

Protection Agency, pp. 12-21. 1978. 

94 
P.7 

13. Chemical and Process Technology Encyclopedia, pp. 387-392. 

1974. 

14. U. S. Environmental Protection Agency. Guideline Series -

Control of Volatile Organic Compound Emissions from 

Manufacture of Styrene-Butadiene Copolymers. U. S. 

Environmental Protection Agency, Research Triangle Park, 

North Carolina. Preliminary Draft, pp. 2-12. 1981. 

15. Pope, A. A. et al. Toxic Air Pollutant Emission Factors - A 

Compilation for Selected Air Toxic Compounds and Sources. 

EPA-450/2-88-006. U. S. Environmental Protection Agency, 

Research Triangle Park, North Carolina, p. 4-216. 1988. 

16. Rubber Products Styrene-Butadiene Rubber Manufacture. 

Emission Test Report General Tire and Rubber Company, 

Mogadore Chemical Plant, Mogadore, Ohio. U. S. 

Environmental Protection Ageney, Research Triangle Park, 

North Carolina. EMB Report No. 79-RBM-4. 

17. Shay, J. J. Styrene-Acrylonitrile. Modern Plastics 

Encyclopedia. 63:88-89. 

18. Energy and Environmental Analysis, Inc. Source Category 

Survey for the Acrylonitrile Industry - Draft Report. 

Prepared for U. S. Environmental Protection Agency, pp. 3-

10, 3-30 to 3-37. 1981. 

19. Click, C. N. and D. O. Moore. Emission, Process and Control 

Technology Study of the ABS/SAN, Acrylic Fiber, and NBR 

Industries. Prepared for U. S. Environmental Protection 

Agency. Pullman Kellog. Houston, Texas, pp. 18, 33. 

1979. 

20. Chemical Profile: Styrene. Chemical Marketing Reporter, 

pp. 49, 50. August 14, 1989. 

21. U. S. Environmental Protection Agency. Locating and 

Estimating Air Emissions From Sources of Acrylonitrile. 

EPA-450/4-84-007a. U. S. Environmental Protection Agency, 

Research Triangle Park, North Carolina, pp. 34-45. 1984. 

22. Hensley, D.S. and CA . Johnson. ABS and Related 

Multipolymers. Modern Plastics Encyclopedia, pp. 6-7. 

1985-1986. 

23. Memorandum from R. Burt and R. Howie, Radian Corporation, to 

L.B. Evans, EPA/Chemicals and Petroleum Branch, January 29, 

1986. Estimates of Acrylonitrile, Butadiene, and Other VOC 

Emissions and Controls for ABS and NBR Facilities. 

95 
P.8 

24. Lantz, J. M. ABS and Related Multipolymers. Modern 

Plastics Encyclopedia, pp. 6,8. 1986-1987. 

25. Considine, D. M. ed. Acrylonitrile-Butadiene-Styrene 

Resins. Chemical and Process Technology Encyclopedia. 

McGraw-Hill Publishing Co., Los Angeles, California, pp. 

32-34. 1974. 

26. Rolston, J. A'. Fiberglass Composite Materials and 

Fabrication Processes. Chemical Engineering, January 28: 

96-110. 1980. 

27. U. S. Environmental Protection Agency. Compilation of Air 

Pollutant Emission Factors. EPA-AP-42. U. S. Environmental 

Protection Agency, Research Triangle Park, North Carolina, 

pp. 4.12-1 to 4.12-3. September 1985. 

28. Letter from Randazzo, C., SPI Composites Institute. 

Comments on draft "Locating and Estimating Air Emissions 

from Sources of Styrene" document. December 1990. 

96 
SECTION 6 

EMISSIONS FROM THE USE OF STYRENE-CONTAINING MATERIALS 

As discussed in Section 3, styrene-based resins are present 

in many materials, including packaging, appliances, building 

materials, furniture, electrical materials, housewares, rubber 

products, paints, adhesives, and automotive and recreational 

equipment parts. Sections 4 and 5 evaluate the potential for 

styrene emissions from styrene production and from the major 

intermediate styrene processors. Often these processors sell the 

resins as pellets, granules, powders, or liquids.1 These resins 

may then be combined with colorants and fillers before they are 

transferred to the fabricator for manufacture of the final 

product. Alternately, the resin may be sold to a separate 

compounding facility for this treatment. The fabricators then 

extrude, inject, or spray styrene-based resins to make the final 

products. 

To provide some idea of the prevalence of styrene-containing 

product manufacture, Table 20 presents an estimate of the total 

number of some of the styrenic resin fabricators in the United 

States. In addition to the resin producers listed in Sections 4 

and 5, an additional 200 distributors and compounders sell 

styrenic resins to fabricators in the United States.1 

The production process descriptions and emissions data 

presented in this section cover some of the most common processes 

and products. Because of styrene's widespread use, all processes 

cannot be included here. Furthermore, emissions data were 

limited. Individuals are encouraged to examine the lists of 

final products in Section 3 to identify specific facilities to 

contact for emissions information. 

This section also describes the results of industrial 

hygiene measurements of the release of styrene from the 

97 
P.10 

TABLE 20. PREVALENCE OF STYRENIC RESIN FABRICATORS 

Type of Facility 

UPR fabricators, cultured marble 

UPR fabricators, marine 

UPR compounders (bulk and sheet molding) 

UPR fabricators, -tubs, showers, spas, and 

hot tubs 

Tire and inner tube manufacturers (SBR use) 

Crystal and/or IPS 

Polystyrene foam producers 

Number 

1,600 

. 977 

28 

197 

56 

29 

237 

Source: References 1 and 2. 

98 
P.11 

thermodegradation of styrene-containing thermoplastics. In 

addition, three categories of styrene emission sources are 

described. The first is styrene emissions from an 

acrylonitrile-butadiene-styrene (ABS) compounding facility that 

receives ABS granules and adds colorants. The second category is 

styrene emissions from unsaturated polyester resins (UPR) use in 

different molding processes. Finally, the process descriptions 

for the manufacture of polystyrene foam products for drinking 

cups, loose fill, and other products are provided; no emissions 

data are available for this category. 

THERMODEGRADATION OF STYRENE-CONTAINING MATERIALS 

One less obvious source of styrene emissions is the 

thermodegradation of styrene-containing materials to form the 

final product. Because the processing of these materials 

typically involves high temperatures, varying amounts of occluded 

styrene monomer may be released. Styrene-containing 

thermoplastics are extruded or molded (by injection, compression, 

or blowing) at temperatures that range from 150 tp 320°C. The 

following information on the release of styrene monomer during 

the processing of PS, impact (IPS), ABS, and SAN is based on 

industrial hygiene investigations conducted in Sweden and 

Finland.3'

4 

In general, the thermostability of these materials is 

dependent on their molecular weight, mode of polymerization, and 

composition.4 Table 21 shows the range of styrene monomer 

released during the thermooxidative degradation of styrenecontaining materials. The temperatures used and the oxygen 

content during combustion were intended to represent those 

encountered in industrial process situations. For PS, typical 

processing temperatures are 150 to 280°C for extrusion and 

injection molding and 190 to 235°c for blow molding.4 

99 
TABLE 21. STYRENE EMITTED FROM THERMOOXIDATIVE DEGRADATION 

(Mg/g, lb/ton)" 

Temperature Impact Acrylonitrile- Styrene-

(°C) Polystyrene Polystyrene Butadiene-Styrene Acrylonitrile 

197 —

b — 7800, 15.6 (68)c 

200 Trace 

208 — — 2300, 4.6 (32) 

218 — — — 2700, 5.4 (3.2) 

224 — 310, 0.62 (3.4) 

240 520, 1.04 (8.0) 

250 740, 1.48 (7.0) 280, 0.56 (3.8) 

o "Uncontrolled emissions, 

tn—II Not measured. 

cStyrene yield is given in parenthesis as the percentage of total loss in weight. 

Source: References 3 and 4. 
P.13 

Polystyrene is the most thermostable of the styrene-containing 

materials studied, and is considered stable during commercial 

molding and extruding at temperatures below 275°C.4 

ACRYLONITRILE-BUTADIENE-STYRENE COMPOUNDING 

The following material was provided by a State air pollution 

control office following source testing of an ABS compounding 

facility.9 Uncontrolled styrene emissions for this facility are 

presented under two different scenarios and the facility's 

original control system, a water spray scrubber, was evaluated 

for its effectiveness in reducing styrene emissions. The 

facility operators and State representatives then installed and 

tested an interim control measure of two packed columns in series 

in an effort to temporarily reduce styrene emissions while 

designing a permanent control system. Once installed, the 

permanent control system was found to be 99.5 percent effective 

in reducing total styrene emissions. The applicability of this 

information to other facilities is not known, nor is there any 

information on the number or location of similar facilities. 

Process Description 

The ABS compounding facility receives granulated ABS resin, 

mixes the resin with dyes and additives, and extrudes the final 

product (Step 1) into pellets for shipment (Figure 19). The 

s plant operates six extruders; all of the extruder vacuum vents 

are pumped to one water ring vacuum pump (Step 2). All die vents 

are also pumped to a common vent and a common blower. The 

gaseous components are pulled into the vent system, while the 

water is discharged to the oil-water separation sump (Step 3). 

The discharge from the oil-water separation sump (Step 4) is then 

sent through a basket strainer and baffled to separate the oil 

from the water. The oil is hand skimmed and the water is sent to 

a rotating biological contactor (RBC) for biological treatment. 

101 
® 

Vacuum Pump 

Water Spray 

Scrubber 

Spray Water 

Drain 

Air-Water 

Separator 

ABS Pellets 

i , , 

© 

Main Exhaust 

Stack 

Secondary 

sources 

Storage and 

loading losses 

Oil-Water 

Separation Sump 

To Biological 

Treatment 

Denotes potential location 

of emission source 

Figure 19. Original Vacuum and Vent System at an ABS Compounding Facility 
P.15 

The RBC sump and the outlet from the RBC are also piped into the 

die vent system. 

Emission Measurements 

The emissions from the die and vacuum pump streams were 

tested under a variety of control situations and are discussed 

below. In addition,-styrene emissions were monitored to compare 

the emissions when the oil-water separation tank was enclosed and 

when it was open. The emissions were measured by gas 

chromatograph (GC) analyses and delta nonaqueous volatile (NAV) 

mass balance. 

The extruder vacuum pump and die vent emissions were tested 

under four scenarios: uncontrolled with the oil-water separation 

tank open and enclosed, and controlled with a water spray 

scrubber with the oil-water separation tank open and enclosed. 

The vacuum pump discharge from the separator was also 

disconnected from the main stack to measure its emissions 

separately. Gas chromatograph styrene measurements were also 

taken around the oil-water separation sump. 

Of the total emissions, the majority were from the vacuum 

pump discharge, with the remainder coming from the die vent. 

Stack emissions increased 20 percent when the oil-water 

separation sump was enclosed due to the reduction in fugitive 

losses. The results showed that the water spray scrubber was 

only 25 percent efficient in reducing styrene emissions, and in 

one measurement the controlled emissions were actually higher 

than uncontrolled emissions. Attempts to reduce vacuum pump 

emissions with a water spray in the outlet line were only 12 

percent effective in overall emission reduction. 

Emission estimates derived from GC analysis were then 

compared with estimates from NAV. The* NAV is a mass balance 

estimate determined by monitoring resin content of the ABS resin, 

pellets produced, vent oil sludge, and vacuum pump discharge 

103 
P.16 

water. In general, GC and NAV were found to agree within 21 

percent. 

Because the water spray scrubber does not adequately control 

styrene emissions, design of a better system was proposed. In 

the interim, two packed columns in series vented to a temporary 

carbon adsorption system were installed. The water/gas mixture 

discharged from the vacuum pump was first sent to an air-water 

separator, and the air leaving the separator was scrubbed in two 

columns. Water was fed to the columns from a recirculation tank. 

A total of 40 gallons per minute (gpm) were circulated through 

each column. About 6 gpm was drained from the recirculation tank 

for treatment in the RBC. The air leaving the second column was 

heated to raise the relative humidity above 50 percent and sent 

to a Calgon unit for carbon adsorption of the styrene. After 

passing through the carbon adsorption bed, the vacuum pump air 

stream combined with the die vent stream. This air stream then 

passed through the water spray scrubber system. Test results 

showed a total styrene emission reduction from the vacuum pump 

exhaust and die vent of 96.4 percent. Table 22 presents the 

emission factors developed from these data. 

Permanent VOC controls were installed on this ABS 

compounding facility at a later date (Figure 20). The air from 

the air-water separator (about 200 standard cubic feet per minute 

(scfm)) is scrubbed in two columns. The outlet of the second 

scrubber passes through a heat exchanger. The air then passes 

through two small carbon beds (2,000 pounds each) and the outlet 

of the second bed is joined with the outlet of the die vent 

system blower. This air then passes through two large carbon 

beds (4,000 lbs each). Follow-up source testing indicated that 

emissions were reduced by more than 99.5 percent for total 

reactive organic compounds. Table 23 presents the emissions 

information for styrene at the outlet of the first large carbon 

bed (a worst case scenario if operating on only one bed), and at 

the outlet of the second large carbon bed. 

104 
TABLE 22. SUMMARY OF SOURCE TESTING DATA FOR AN ABS 

COMPOUNDING FACILITY UNCONTROLLED AND WITH TEMPORARY CONTROLS 

Emission 

source 

Extruder vacuun 

punp and die 

vent 

Same as above 

Same as above 

Same as above 

Extruder vacuum 

puip 

Same as above 

Die vent 

Same as above 

Extruder vacuun 

punp and die vent 

Same as above 

Same as above 

Same as above 

Extruder vacuun 

pump 

Control 

device 

Mater scrubber 

none 

Mater scrubber 

none 

Mater scrubber 

none 

Mater scrubber 

none 

Mater scrubber 

none 

water scrubber 

none 

scrubber/carbon 

adsorption 

Data basis 

(NAV or GO* 

GC 

GC 

GC 

GC 

GC 

GC 

GC 

GC 

NAV 

NAV 

NAV 

NAV 

GC 

Emission factor 

(lbs sty/103 lbs product 

or Kg sty/Mg product) 

1.196 

1.676 

1.033 

1.366 

1.129 

1.113 

0.013 

0.013 

1.420 

1.790 

1.175 

1.307 

0.006 

Conrnents 

o 

Ul 

Nonnai process operation, oil-HjO separator tank 

enclosed, 6 lines running (max. production rate) 

Same as above 

Nonnai operation, oil-H-,0 separator tank open, higher 

fugitives, less process emissions 

Same as above 

Vacuun pump discharge measured separately from die 

vent 

Same as above 

Same as above 

Same as above 

Nonnai operation, 6 lines running, oil-HjO separator 

tank enclosed 

Same as above 

Nonnai operation but discharges measured separately, 

emission factor represents combined emissions 

Same as above 

Measured at carbon adsorption outlet, oll-H-,0 punp 

separator enclosed 

(continued) 
TABLE 22. (Continued) 

Emission 

source 

Extruder vacuun 

punp and die vent 

Extruder vacuum 

punp 

Control 

device 

scrubber/carbon 

adsorption 

none 

Data basis 

(NAV or GC)* 

GC 

GC 

Emission factor 

(lbs sty/103 lbs product 

or Kg sty/Mg product) Comments 

Same as above scrubber GC 

0.042 

1.291 

0.859 

Main plant exhaust after control, oil-HjO separator 

enclosed, vacuun pumps scrubber and adsorber 

controlled, die vents scrubber controlled 

Uncontrolled vacuun punp emissions measured prior 

to scrubber 

Emissions measured after scrubbers and prior to 

carbon adsorption 

o 

ON 

'NAV « nonaqueous volatile (mass balance of residual hydrocarbons in the resin, pellets, vent oil and Hastewater). 

GC = Gas Chromatograph Analysis 

TJ 

oo 
Vent Hoods 

Die Vents 

BerlngerOven 

RBC Sump (A) 

RBC(B) 

•~-g >~ -

Blower #1 

Blower #2 

nl 4000 b .Carbon 

Adaocptlon Peek 

O 

Extruder 

Vacuum 

Parts -

lAlr/H^D 

Vacuum Pumps 

•HXJ—QHXJ-1 

Alr/HpSeparator 

Scrubber #2 

Scrubber #1 

•HgQ Make-up 

Stack 

i r j 

4000bCaibon 

Adsorption Pack *XJAlr 

Heat 

Exchanger 

Air 

H2 0 

Air 

Blowdown 

ip I L_ H r\ »i 

Vent 

Sump 

20001b 

Carbon 

Adsorbtlon 

Pack 

H^O Make-up 

20001b 

Carbon 

Adsorbtlon 

Pack 

_Alr £_ 

RBC Sump 

RBC City Sewer 

fi 

Figure 20. Permanent VOC Controls at an ABS Compounding Facility 

P 

Ico 
P.20 

TABLE 23. SUMMARY OF ABS COMPOUNDING FACILITY SOURCE TEST 

DATA AFTER INSTALLATION OF PERMANENT CONTROLS* 

Emission Source 

Outlet of first large 

carbon bed 

Outlet of first large 

carbon bed 

Vacuum pump outlet 

Vacuum pump outlet 

Outlet of second 

small carbon bed 

Outlet of first small 

carbon bed 

Outlet of second 

Styrene Emission 

Factor4" 

0.0012 

0.0017 

1.5157 

1.6507 

0.0012 

0.0017 

0.0017 

Comments 

small carbon bed 

Six lines running 

(max. production 

rate) 

Five lines running 

Six lines running 

Five lines running 

Six lines running 

after change of small 

carbon bed 

Five lines running 

after change of small 

carbon bed 

Five lines running 

after change of small 

carbon bed 

"Measured by gas chromatograph. 

blbs/103 lb product or kg/Mg product. 

108 
P.21 

UNSATURATED POLYESTER RESIN USE 

Styrene-containing UPR is used in the manufacture of boats, 

vehicle components, bowling balls, bathroom fixtures, gasoline 

storage tanks and other products. 

Unsaturated polyester resins can be used in reinforced or 

non-reinforced applications. Eighty percent of UPR is 

reinforced, usually with glass fibers, and extended with various 

inorganic filler materials such as calcium carbonate, talc, mica 

or small glass spheres.*'7 These composite materials are often 

referred to as fiberglass reinforced plastic (FRP), or simply 

fiberglass.* The Society of the Plastics Industry designates 

these materials as "reinforced plastic/composites" (RP/C). Also, 

advanced reinforced plastic products are now formulated with 

fibers other than glass, such as carbon, aramid and aramid/carbon 

hybrids.7 Reinforced UPR is used to make boats and marine 

accessories, tub and shower stalls, transportation components and 

recreational vehicle components.* Nonreinforced UPR is used in 

casting processes to make simulated marble products, cast 

furniture parts, buttons, and bowling balls. 

Molding processes are either closed or open. Closed molding 

techniques are compression, injection, pultrusion, continuous 

lamination, marble casting, bag molding, and resin transfer. 

Open molding processes are hand layup, filament winding,

 an(i 

spray layup. Selection of closed or open molding depends on the 

•size and volume of the product to be manufactured. Open molding 

is used for large parts such as boats and recreational vehicle 

structures. Open molding processes of spray layup and hand layup 

*As used in this report, "fiberglass" means glass fibers or 

fiberglass reinforced plastic. The term does not necessarily 

mean "FiberglasTM, trademark of Owens/Corning Fiberglas 

Corporation, Toledo, Ohio. 

109 
P.22 

offer advantages for firms that produce a limited number of units 

for each mold, require rapid startup, and operate with restricted 

capital for tooling. Because of limited production and/or unique 

designs, many fabricators will continue to rely on open mold 

fabrication. 

In descending order of resin use, the UPR molding processes 

are:7 

Spray layup (sprayup); 

Hand layup; 

.Continuous lamination; 

Press molding; 

Marble casting; ~ """ 

Pultrusion; 

Filament winding; 

Resin transfer molding; and 

Bag molding. 

Process descriptions for these molding processes are given below. 

Open Molding 

Most open mold fabricators use similar processes to produce 

products with varying composition, sizes, and shapes. For 

products with a smooth, durable surface, a smooth and highly 

polished mold is required. For many products, a catalyzed gel 

coat is applied as the initial step. The resins are generally 

either hand rolled or sprayed into the fiberglass reinforcement. /"•' 

Some hand rolling is essential even when the resin is sprayed, 

for removing voids and ensuring proper compaction of resin and 

reinforcing material. 

;. •-:' '.-Mostopen moldfabrication 1 facilities.consist ;.of one or more 

open production areas. In these open areas, a large number of 

exhaust fan outlets are provided. Emissions can be reduced by 

using airless spray guns, spray booths for gel coating and resin 

application, isolated work bay operations, and air filtration. 

110 
P.23 

Spray Layup— 

In UPR spray layup, the mold defines the shape of the outer 

surface, and the mold itself is usually made of reinforced 

plastic. The mold is first coated with a wax to ensure removal 

after curing. A layer of gel coat is then sprayed on to the mold 

to form the outermost surface of the products. Gel coats are 

highly pigmented unsaturated polyester resins that provide a 

smooth, colored surface that gives the appearance of a painted 

part.' The gel coat is allowed to cure for several hours but 

remains tacky so subsequent resin layers adhere better. The 

polyester resin is applied with a spray gun that has a glass 

chopper attachment. This allows simultaneous spraying of resin 

and chopped glass onto the mold. The spray gun has separate 

resin and catalyst streams which mix as they exit the gun. Air 

spray guns require a large volume of air flow at high pressures. 

This provides good control over spray patterns; however, this 

type of spraying contributes to excessive fogging, overspray, and 

bounce back, resulting in increased emissions and material loss. 

To reduce styrene emissions, air-assisted airless spray guns can 

be used to apply gel coats and resins. Because high pressure is 

not needed at the nozzle, air-assisted airless spraying results 

in lower emissions and less material loss. Unsaturated polyester 

resins designed for use in spray layup-are promoted for cure at 

room temperature and usually are catalyzed with a liquid peroxide 

such as methyl ethyl ketone peroxide (MEKP).9 

Hand Layup— 

Hand layup involves the same initial steps (up through 

application of the gel coat) as used in spray layup. Following 

gel coat application, alternate layers of catalyzed polyester 

resin and reinforcement material are applied. The ratio of resin 

to glass is usually 60 to 40 by weight, but varies by product. 

Each reinforcement layer is "wetted out" with resin, and then 

rolled out to remove air pockets. The process continues until 

111 
P.24 

the desired thickness is achieved. Hand layup is also a room 

temperature curing process. 

Filament Winding— 

Filament winding, shown in Figure 21, is the process of 

laying a band of resin impregnated fibers onto a rotating mandrel 

surface in a precise geometric pattern, and curing them to form 

the product. This is an efficient method of producing 

cylindrical parts with optimum strength characteristics suited to 

the specific design and application. Glass fiber is most often 

used for the filament, but aramid, graphite, and sometimes boron 

and various metal wires may be used. The filament can~be wetted 

during fabrication, or previously impregnated filament 

("prepreg") can be used. The three most common winding patterns 

are circumferential, helical, and polar winding. The various 

winding patterns can be used alone or in combination to achieve 

the desired strength and shape characteristics. Mandrels are 

made of a wide variety of materials and, in some applications, 

remain inside the finished product as a liner or core. Example 

products are storage tanks, fuselages, wind turbine and 

helicopter blades, and tubing and pipe.7 

Closed Molding 

Closed molding systems reduce styrene emissions by 

eliminating the requirement for atomization of the resin. The 

most common closed molding processes are press molding, marble 

casting, pultrusion, continuous lamination, resin transfer 

molding, and bag molding. Of these, the two largest categories 

are press molding and marble casting. 

112 
w 

Polar Winding (J 

Figure 21. Typical Filament Winding Process 
Press Molding— 

Press molding includes compression, injection and transfer 

molding, and requires a large hydraulic press typically ranging 

from 454 to 4536 Mg (500 to 5000 tons) in capacity. Press 

molding uses either bulk molding or sheet molding compounds of 

resin and reinforcing materials.8 

Bulk molding compounds are produced in rope or solid bulk 

form, and isheet molding compounds are produced in sheet form. 

Generally the UPR compounders have indoor UPR tanks containing 

less than 37,853 liters (10,000 gallons) each. The UPR is pumped 

from the storage tanks to a mixing tank where fillers ^primarily 

calcium carbonate, clay or alumina) and catalysts are added. To 

make sheet molding compounds, the resulting paste is reinforced 

with glass fibers and formed into sheets on a continuous basis. 

To make bulk molding compounds, the paste is placed in a mixer 

with glass fibers. After compounding, the product is extruded 

into rope form or packaged in bulk form. Air emissions arise 

from storage tanks, mixing tanks, and mixing rooms. 

Compression molding uses sheet molding compound where the 

sheet is compressed between heated molds and cured. Injection 

and transfer molding use bulk molding compound. The molding 

compound is forced through a small opening into a closed heated 

mold and cured.8 

Continuous Lamination— 

Garage doors, truck bed liners, patio covers, skylights, and 

solar collectors are some of the products made with unsaturated 

polyester resins using the continuous lamination process. 

As shown in Figure 22, the polyester resin is first applied 

to a film on an impregnation table- on a conveyor belt. The film 

forms the bottom surface of the product. This film can be made 

114 
Resin Metering Device 

Resin Mix 

ui 

Jk^PlckerRoll

 To^m 

Heated Wetout 

Table 

Bottom Film 

Squeeze Rolls 

Cure Area Cross Cut Saw or Shear 

Rim 

Rewind 

Edge Trim 

?n o o o 

* - & 

Pull Rolls 

Inspection Area 

Stacking Device 

Figure 22. Typical Continuous Lamination Production Process 
P.28 

of polyester, cellophane, or nylon. The resin usually contains 

additives such as calcium carbonate or aluminum trihydrate to 

increase weather and flame resistance. Chopped glass is then 

added to the wet coat of resin, and a top layer of film is added 

and the layers are pulled through rollers to remove air bubbles. 

The conveyor belt then carries the laminate to a curing oven 

(200°C). After exiting the oven the films are removed and the 

laminate is trimmed to the desired size.7 Impregnation ensures a 

high degree of control of fiber/resin ratio and catalyst/resin 

ratio. Styrene emissions are reduced as compared to air 

sprayers. 

Synthetic Marble Casting— 

The polyester resin used in synthetic marble casting usually 

has higher viscosity and lower monomer levels than the resins 

used for laminating and gel coats. Fillers and colorants are 

mixed with the resin in large vats. To achieve the marbled 

effect, the colorants are often hand stirred. The mixed resin is 

then hand poured into partially closed molds. The resin is cured 

at room temperature and, after curing, the mold is removed. Gel 

coats may also be used, in which case, they are applied to the 

mold surface before pouring in the resin. Sources of emissions 

include equipment leaks, UPR storage tanks, process operations, 

and transfer and handling operations. The major sources of 

process operation emissions are the gel coat area and casting 

areas, where UPR is mixed and poured into molds.

 r 

Pultrusion— 

Pultrusion, which can be thought of as extrusion by pulling, 

is used to produce continuous cross-sectional lineals similar to 

those made by extruding metals such as aluminum. Reinforcing 

fibers are pulled through a liquid resin mix bath and into a long 

machined steel die, where heat initiates an exothermic reaction 

to polymerize the thermosetting resin matrix. The composite 

emerges from the die as a hot, constant cross-sectional profile 

116 
P.29 

that cools sufficiently to be fed into a clamping and pulling 

mechanism. The product can then be cut to desired lengths.7 The 

final pultruded product is typically at least 70 percent 

reinforcement by weight. These products are used in the 

electrical and building industries. 

Resin Transfer Molding— 

Resin transfer molding is a low pressure closed molding 

process which is normally carried out at room temperature. In 

the process, continuous or chopped strand glass fiber mats are 

placed in a mold, with catalyzed resin injected after the mold is 

closed. Because no resin surfaces are exposed to air during 

curing, styrene emissions from this molding process are greatly 

reduced as more styrene is retained in the mixture and added to 

the polymer as it cures, instead of volatilizing out of the 

mixture. Gel coats, which are often used with resin transfer 

molding, are applied to the molds (which may be reinforced 

plastic). After the gel coat cures, glass reinforcement is 

placed in the mold and resin is injected. This molding process 

is best used for intermediate volume production of small to midsized components such as restaurant seats, hatches, doors, 

automotive parts, tubs, and shower units.8 

Bag Molding— 

Bag molding is best used to produce an intermediate volume 

of small to mid-size components such as seats, boat hatches, boat 

deck structures, and other items with shallow draft molds. Bag 

molding is conducted in sealed molds at room temperature. The 

process is initiated with gel coat applied to the surface of the 

mold. Glass reinforcing fibers and other materials are carefully 

cut to fit the mold and placed over it. Catalyzed resin is 

sprayed, pumped or poured over the layup. Once the layup 

materials are in place, the exposed area is covered with special 

layers of plastic which are sealed to the edges of the mold. 

Styrene emissions occur primarily from gel coat layup, UPR 

117 
storage, and handling operations. The bag molding process uses a 

bag or flexible membrane to apply pressure during molding; 

usually in conjunction with an autoclave.10 A reinforced 

laminate is layed up by hand or sprayed and pressure is applied 

by drawing a vacuum under a cellophane, vinyl, or nylon bag 

covering it. This assembly is then heated under pressure in an 

autoclave. The use of bag molding allows the final product to 

have a higher fiberglass to resin ratio.' 

Spas/Tubs/Showers— 

Open mold processes (spray layup) are used to fabricate 

spas, tubs, and showers. The process consists of gel coat 

sprayup and laminating operations. The polyester resin is hand 

rolled to build successive layers of reinforced plastic. The 

product is usually cured at room temperature. Significant 

sources of emissions are from UPR storage, transfer operations, 

and open mold operations. 

Fiberglass Boat Production— 

The fiberglass boat industry is a large consumer of UPR, 

with facilities scattered throughout the United States. The 

production process is discussed separately here because no one 

specific process is used.9 

Currently, there are over 900 fiberglass boat plants in the 

United States. The distribution of large fiberglass boat 

manufacturing facilities in 1987 by number in each State is shown 

in Table 24. Only 16 States do not have any fiberglass boat 

manufacturing establishments.11 Furthermore, 10 States have more 

than 10 boat manufacturing facilities and represent 65 percent of 

the facilities: California, Florida, Illinois, Indiana, 

Michigan, North Carolina, South Carolina, Tennessee, Texas, and 

118 
P.31 

TABLE 24. GEOGRAPHIC DISTRIBUTION OF THE FIBERGLASS BOAT 

INDUSTRY BY NUMBER OF FACILITIES 

Florida 

Tennessee 

California 

Texas 

Michigan 

South-Carolina 

Indiana 

Illinois 

Washington 

North Carolina 

Arkansas 

Massachusetts 

Missouri 

Louisiana 

Georgia 

Maryland 

Minnesota 

Rhode Island 

Maine 

Wisconsin 

New Jersey 

Ohio 

Alabama 

Arizona 

Kansas 

Oklahoma 

Oregon 

Connecticut 

Kentucky 

Mississippi 

New York 

Pennsylvania 

Iowa 

Nebraska 

Utah 

Virginia 

77 

40 

23 

21 

14 

14 

13 

12 

11 

10 

9 

9 

9 

9 

8 

8 

8 

7 

7 

6 

5 

5 

4 

4 

4 

4 . 

4 

3 

3 

3 

3 

2 

1 

1 

1 

1 

TOTAL: 363 

Source: Reference 11. 

119 
P.32 

Washington. The geographic distribution of major fiberglass boat 

manufacturing facilities by State is presented in Figure 23. 

Points that represent more than one establishment in a given city 

are assigned a numerical value. In general, the major locations 

of fiberglass boat manufacturing facilities are centered near 

lakes, rivers, and coastal areas.9 

The styrene concentration of UPR used in fiberglass boat 

manufacture is usually 35 to 45 percent, and the styrene content 

of the gel coat is typically 45 to 50 percent. The most common 

fiberglass boat production process is contact molding, both spray 

layup and hand layup (Figure 24).1C Concave female molds are 

preferred for boat hulls and decks as they leave smooth~outer 

surfaces (male molds leave smooth inner surfaces). As discussed 

in the spray layup description, an airless spray gun is normally 

preferred. Gel coat application typically takes place in a 

ventilated spray area in boat manufacturing facilities. Hand and 

spray layup, as well as automated fabrication techniques, can be 

used in the manufacture of fiberglass boats. Often the first 

layer is allowed to cure to the touch before subsequent layers 

are applied to the desired thickness. Automated layup of large 

hull boats involves the simultaneous mechanical application of 

resin and reinforcement material, and may still require hand 

rolling to remove air bubbles. Spray layup is used for small 

parts, hulls, and decks. Hand rollers are also used to remove 

air bubbles. Small parts are usually produced in a ventilated 

booth in the molding area. A separate assembly room is used for 

sanding parts and assembling the entire craft. Carpet and other 

fixtures are also installed in the assembly area.9 

A less common molding method for the fiberglass boat 

manufacturing industry is the resin transfer molding process 

typically used to manufacture small parts such as boat seats, 

hatch covers, and bait boxes." 

120 
121 

1 ^*"M»»* 

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)• • 

l • \ C 1 

\ * 1 r l " 

12 J* v"C— - \ L |V 

» ^ . lV^v i 

7 1 1 ^r. / 1 \ ^\ •••a ^ ^ 

^ " ^ / / ^»*» >J / 1 \ A £' 

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V- \ Y «* J 

^

s

- v A \_**l 

F i

-

2 3 - ^ ^ 

/ ^ 1 

1 j^ A • 

1682722F 
Molding Room Assembly Room H 

Coat Mold 

with Wax 

NJ 

Hull and Deck Fabrication 

• apply resin 

• lay fiberglass reinforcement 

• wet out 

Remove 

from Mold 

Gel 

Spray th 

Small Parts Spray Booth 

Small Parts Fabrication 

• spray on 

> wet out 

Remove 

from Mold 

• Sand 

• Assemble boat 

• Install carpet and 

accessories 

% 

Figure 24. Fiberglass Boat Production Process 

co 
P.35 

Emission Measurements by Molding Process 

The U. S. Environmental Protection Agency has published 

emission factors for fabrication processes using styrene as the 

monomer.7 These emission factors, shown in Table 25, are 

presented as pound VOC per pound monomer used. Styrene is by far 

the most common monomer used.7 Table 25 includes emission 

factors for vapor-suppressed (VS) resins, which can be used to 

reduce VOC emissions in place of nonvapor-suppressed (NVS) 

resins. Discussions with industry representatives indicate, 

however, that VS gel coats are not used, nor are VS resins used 

in closed molding processes.13 

The California Air Resources Board (CARB) has also developed 

emission factors for UPR by molding process."'14 These emission 

factors are shown in Table 26, and are based on resin monomer 

content, layup process, and microenvironmental conditions (such 

as temperature, indoor versus outdoor processes, and 

ventilation). It should be noted that the CARB emission factors 

are given in pounds of monomer emitted per pound of monomer used. 

The emission factors published by EPA and CARB are similar 

for many of the processes shown in Tables 25 and 26. Notable 

exceptions are the emission factors for hand layup. The EPA 

emission factors are much lower than CARB's emission factors. 

Sample Calculation Using EPA Emission Factors7— 

A fiberglass boat building facility consumes an average of 

500 lb per day of styrenercontaining resins using a combination 

of hand layup (65%) and spray layup (35%) techniques. The 

laminating resins for hand and spray layup contain 41.0 and 42.5 

percent, respectively, of styrene. The resin used for hand layup 

contains a vapor-suppressing agent. 

123 
P.36 

TABLE 25. VOC EMISSION FACTORS FOR POLYESTER RESIN PRODUCT 

FABRICATION PROCESS" 

(Pound VOC emitted/pound monomer used) 

Resin 

Process NVS V Sf c 

Gel Coat 

NVS VSb 

Hand Layup 

Spray Layup . 

Continuous 

Lamination 

Pultrusion* 

Filament Winding" 

Marble Casting 

Closed Molding9 

0.05-0.10 

0.09-0.13 

0.04-0.07 

0.04-0.07 

0.05-0.10 

0.01-0.03 

0.01-0.03 

0.02-0.07 

0.03-0.09 

0.01-0.05 

0.01-0.05 

0.02-0.07 

0.01-0.02 

0.01-0.02 

0.26-0.35 

0.26-0.35 

0.08-0.25 

0.08-0.25 

"Ranges represent the variability of processes and sensitivity of emissior 

to process parameters. Single value factors should be selected with 

caution. NVS = nonvapor-suppressed resin. VS = vapor-suppressed resin. 

"Factors are 30-70% of those for nonvapor-suppressed resins. 

cGel coat is not normally used in this process. 

"Resin factors for the continuous lamination process are assumed to apply. 

•Resin factors for the hand layup process are assumed to apply. 

'Factors unavailable. However, when case parts are subsequently sprayed 

with gel coat, hand and spray layup gel coat factors are assumed to apply 

"'Resin factors for marble casting, a semiclosed process, are assumed to 

apply. 

Source: Reference 7. 

|lh:c 124 
P.37 

TABLE 26. MONOMER-BASED EMISSION FACTORS FOR POLYESTER 

RESIN/FIBERGLASS OPERATIONS 

(Pound monomer emitted/pound monomer used) 

Process 

Hand Layup Only 

Spray Layup Only 

Hand and Spray 

Marble Casting 

Continuous 

Lamination 

Pultrusion 

Filament Winding 

Closed Molding 

NVS 

0.16-0.35 

0.09-0.13 

0.11-0.19 

0.01-0.03 

0.06-0.13 

0.06-0.13 

0.06-0.13 

0.01-0.03 

Resin 

VS 

0.08-0.25 

0.05-0.09 

0.06-0.13 

0.01-0.03 

0.06-0.13 

0.06-0.13 

0.03-0.09 

0.01-0.03 

Gel 

NVS 

47 

0.26-0.35 

0.31-0.38 

0.26-0.35 

NA 

NA 

0.26-0.35 

NA 

Coat 

VS 

0.24-0.33 

0.13-0.25 

0.16-0.27 

0.13-0.25 

NA 

NA 

0.13-0.25 

NA 

NA - Not applicable; gel coat normally not used for these processes. 

Source: References 12 and 14. 

125 
P.38 

From Table 25, the factor for hand layup using a vaporsuppressed resin is 0.02 - 0.07 pounds VOC per pound monomer 

used. The factor for spray layup is 0.09 - 0.13 pounds VOC per 

pound monomer used (NVS). Assuming the midpoints of these 

emission factor ranges, and assuming that all VOC emissions are 

styrene, total styrene emissions are: 

(500 lb) X [(0.41)(0.04)(0.65) + (0.425)(0.11)(0.35)] 

=13.5 lb/day. 

The emission factor ranges shown for marble casting in both 

tables include emissions for both gel coat spraying and casting. 

In general, the styrene emissions from synthetic marble~casting 

are expected to be lower than those from other processes because 

of the closed mold nature of the process. Emissions vary with 

the amount of time the resin is exposed to air, and the majority 

of emissions were due to gel coat spraying. 

For continuous lamination, exposure of the resin surface to 

air at the impregnation table is a source of styrene emissions. 

In addition, the ovens and the final sawing operations release 

some uncured resin to the atmosphere. The emissions from 

pultrusion operations are assumed to be the same as continuous 

lamination. 

The prevalence of emission control use in the UPR industry 

is not known. The 1982 California study found that VS resins 

were used for 26 percent of resin and gel coat application. 

Vapor suppressants are typically paraffin waxes that reduce 

styrene emissions by migrating to the surface and reducing 

volatilization of styrene. In laminating resins, the vapor 

suppressant content can range from 0.3 to 0.6 percent by weight. 

Other vapor suppressants in use are thermoplastics and fatty acid 

esters. 

Other ways to reduce styrene emissions would be to change 

from open to closed molding, reduce rollout times, and in general 

126 
P.39 

improve housekeeping. In addition, the amount of polyester 

resin used can be reduced by redesigning products, adding more 

fillers, and improving spray gun efficiency. Reformulation of 

UPR could also be used to reduce the monomer content in the 

resin. 

Emission Measurements for Fiberglass Boat Manufacture 

Styrene can be emitted during storage and transfer of the 

polyester resin and from the lamination area. Resin is typically 

stored in outdoor temperature-controlled tanks and transferred to 

55-gallon drums for spray application. Emissions from these 

sources are expected to be small compared to the process 

emissions.9 

As discussed previously, styrene emissions occur during gel 

coat and resin application and from resin curing. Gel coats are 

typically sprayed on and the resins are applied either by hand or 

spray layup. The emission factors from hand and spray layup are 

shown in Tables 25 and 26. 

Several factors influence the styrene process emissions 

during fiberglass boat manufacture. These include resin 

temperature, air temperature, air velocity in the lamination 

area, mold surface area, and spray gun transfer efficiency 

(Table 27). The reader is encouraged to contact the fiberglass 

boat manufacturing facility to obtain specific information on the 

layup process used and environmental conditions in the lamination 

area in order to better estimate styrene emissions. 

Control of styrene emission from fiberglass boat 

manufacturing can be accomplished with several of the options 

described above for UPR use including:9 

Reduction of styrene content in resin; 

Improved transfer efficiency of spray guns; 

127 
Resin temperatures 

Air temperatures 

Spray gun 

pressure/equipment 

atomization 

Air velocity in lamination 

area 

Mold surface area 

Resin/gel coat styrene 

content 

Emissions increase as temperature 

rises 

Emission increase as temperature 

rises 

Greater pressure increases the 

atomization which increases the 

overspray 

Greater air flow may increase 

evaporation resulting in increased 

emissions and decreased 

concentration 

Greater surface area allows more 

vaporization in terms of total mass 

Increase emissions from increased 

styrene monomer content 

Source: Reference 9. 

128 
P.41 

Use VS resins; and 

Use of add-on controls. 

The use of low styrene resins (35 percent styrene versus 43 

percent) can potentially reduce total styrene emission by 19 

percent from resin application and curing. Problems with 

application may occur as viscosity increases, and curing problems 

may result in structural defects. By improving the transfer 

efficiencies of the spray guns used to apply gel coat and resin, 

styrene emissions due to overspray can be reduced to 42 percent 

for gel coat and 33 percent for resin spray layup.9 Another 

option is the use of VS resins which may reduce styrene emissions 

by 30 to 50 percent during curing. However, the resins form a 

wax layer during curing which must be thoroughly removed between 

each laminate application to ensure interlaminate bonding. If 

maximum strength is not required, reducing the curing time 

between laminate applications can partially address the wax layer 

buildup problem.12 Because of the difficulty in removing the wax 

layer, VS resins are only suitable for selected applications. 

Add-on controls that have been evaluated for use by the 

fiberglass boat manufacturing industry include incineration, 

adsorption (mass transfer) systems, and absorption (wet scrubber) 

systems. None of these add-on controls are currently used, 

however.13 Problems (primarily economic) with the use of add-on 

controls by the fiberglass boat manufacturing industry are due to 

the high flow rates and low VOC concentrations in the exhaust. 

POLYSTYRENE FOAM 

Polystyrene foam (PSF) products consist of foam sheet, foam 

board, and expandable beads. These products are manufactured by 

either extrusion or expandable bead blowing. The density, 

strength, formability, and insulating qualities of PSF make it an 

ideal material for packing "peanuts," hamburger boxes, and hot or 

cold drink cups, and many other products. A 1988 estimate of end 

uses for polystyrene resin indicates that foam packaging accounts 

129 
P.42 

for 26 percent, disposables account for 16 percent, consumer and 

institutional products account for 16 percent, and expandable 

polystyrene (EPS) beads account for 11 percent of total United 

States polystyrene production. The remainder goes into 

electronics, compounding, furniture manufacturing, and 

construction.15 Most extruded PSF products are manufactured by 

polystyrene producers. Blowing agent is incorporated into the 

polystyrene as it is extruded. Expanded polystyrene products, 

however, are made from polystyrene beads which contain an 

inactive blowing agent. These beads are usually produced by the 

large chemical companies, but they are expanded and molded at 

different facilities. Although no information on styrene 

emissions from the manufacture of polystyrene foam was found in 

the literature, process descriptions and facility locations are 

provided. Table 28 lists the major end uses of PS foam board and 

sheet and presents total United States consumption of PS foam 

products in 1988. Table 29 indicates the number of PSF producers 

in the United States by State. 

Process Description 

Polystyrene is foamed through the use of physical blowing 

agents that are gases or liquids that are soluble in the molten 

polymer under pressure. Under depressurization, the blowing 

agent volatilizes, causing the polymer to foam through the 

formation of gas cells. 

Polystyrene Foam Sheet— 

The formation of PSF sheet is an extrusion process, commonly 

using two extruders in series or one extruder with two sections. 

The process produces foam sheets 1 to 7 mm thick, with densities 

of 32 to 160 kg/m3.

20 A typical extruded PSF foam sheet 

manufacturing process flow diagram is shown in Figure 25. 

130 
P.43 

TABLE 28. DOMESTIC CONSUMPTION OF POLYSTYRENE FOAM BY END USES 

1988 1988 

End Use (Mg) (MM lb) 

Extruded Foam 

Board 66,679 147 

Sheet 

Single Service Containers 

Stock Food Trays 

Egg Cartons 

Other Foamed Sheet 

Total Foamed Sheet 

Expandable Beads 

Building and Construction" 

Cups and Containers 

Packaging 

Loose Fill 

. Other EPS Products 

Total EPS Bead Products 

"Values include construction uses other than insulation, such as 

wall and ceiling coverings and concrete filler. 

Source: Reference 16. 

156,038 

86,184 

36,288 

15.876 

361,065 

77,112 

75,298 

48.082 

27,216 

35,401 

253,109 

344 

190 

80 

_25 

796 

170 

166 

106 

60 

56 

558 

131 
P.44 

TABLE 29. DISTRIBUTION OF PSF PRODUCERS BY STATE 

Sheet, Film, Board, and Block Producers 

Including Foam Blowers and Extruders 

State Number of 

' Facilities 

California 23 

Pennsylvania 19 

Michigan 14 

Mississippi 14 

New York 14 

Ohio 14 

Illinois 12 

Massachusetts 12 

Georgia 11 

Missouri 9 

New Jersey 9 

Texas 8 

Arkansas 7, 

Connecticut 7 

Florida 6 

Washington 6 

Indiana 5 

Wisconsin 5 

Colorado 4 

Kentucky 4 

North Carolina 4 

Virginia 4 

Maryland 3 

Minnesota 3 

Tennessee 3 

Alabama 2 

Iowa 2 

Nebraska 2 

Rhode Island 2 

South Carolina 2 

Arizona 1 

Hawaii 1 

Idaho l 

Kansas 1 

New Hampshire l 

Oklahoma 1 

TOTAL: 237 

Source: References 17, 18, and 19, 

132 
OJ 

Virgin Polystyrene Resin, 

Nucleating Agent 

Reclaimed 

Resin 

Blowing Agent Storage 

Screen 

Primary /y^- J 

Extruder v£> — 

Scrap Sheet L. 

T~ ^# Scra 2 p Grinder 

Transport Air 

Polystyrene Thermoformer 

Foam Sheet _ 

Transport 

Air 

4 

m^ 

Scrap Resin 

Storage Silos 

^>^N ^P^>s V^ S 

Scrap Grinder 

YXJ 

4-

Sales 

-&r j Scrap Resin 

I Repellstlzer 

(optional) 

Figure 25. Flow Diagram of a Typical Polystyrene Foam Sheet 

Manufacturing Process 
P.46 

Polystyrene pellets are mixed with a small amount (0.2 to 2 

percent) of powdered nucleating agent such as talc, or a 

combination of citric acid and bicarbonate of soda (Step l).20 

This mixture is fed into the primary extruder (Step 2). The 

extruder is heated to provide an increasing temperature profile 

along its length, so that the polystyrene melts. The blowing 

agent is injected as a liquid, under high pressure, into the 

primary extruder where it mixes with the molten polystyrene. A 

screen is used to remove impurities from the molten polystyrene 

before it enters the secondary extruder. The secondary extruder 

introduces a cooling profile that increases the mixture's 

viscosity and give it enough strength to contain the blowing 

agent as it expands (Step 3). As the viscous polystyrene mix 

leaves the second extruder through a die, it foams and partially 

solidifies. The blowing agent bubbles attach to the nucleating 

agent and a cellular structure is formed. 

An annular extrusion die is used in extruded polystyrene 

sheet production, resulting in a tubular form (Step 4). Foaming 

initiates near the die outlet where the pressure rapidly 

decreases, allowing the blowing agent to volatilize. As the 

foamed polystyrene passes through the die, compressed air is 

applied, forming a skin on the outer surfaces. Additional 

foaming occurs outside the die as the polystyrene tube passes 

over a forming mandrel, which determines the final circumference 

of the foam tube (Step 5). At the end of the mandrel the tube is 

split lengthwise, flattened out, and an S-wrap, or sheet wrapping 

unit, winds the sheet into a roll (Step 6). The PSF sheet is 

then stored for two to five days. During this time, a portion of 

the blowing agent diffuses out of the foam cells and is replaced 

with air. This results in an optimum ratio of air to blowing 

agent within the foam cells, which will allow for postexpansion 

of the PSF during thermoforming. 

Thermoforming is a process in which the extruded PSF sheet 

is reheated, then pressed between the two halves of a metal moid 

to form the desired end product such as fast-food containers 

134 
P.47 

(Step 7). After thermoforming, the molded shape is trimmed, 

sometimes printed, and packaged. Resulting scraps are ground and 

sent to scrap storage silos. This scrap is introduced into the 

primary extruder with virgin polystyrene. Polystyrene scrap 

typically makes up 35 percent of the total polystyrene fed to the 

primary extruder. 

Extruded Polystyrene Foam Board— 

Polystyrene foam board ranges from 1.25 to 15 cm thick, with 

densities of 27 to 66 kg/m3. The extrusion of PS foam boards is 

identical to that of PS foam sheets (Step 1: mixing PS pellets 

with necleating agent, Step 2: primary extrusion, Step 3: 

secondary extrusion), with the exception that a simple slit 

aperture die is used instead of an annular die so that board is 

extruded as slabs rather than a tube (Step 4). Following cooling 

of the PS board, it is trimmed to size and packaged. A typical 

PSF board manufacturing process flow diagram is shown in 

Figure 26. Some board is laminated with facing materials that 

act as a vapor barrier or aid in the retention of low 

conductivity gas.21 

Expandable Polystyrene— 

Expandable polystyrene is produced from spherical 

polystyrene beads which have been impregnated with a volatile 

hydrocarbon such as n-pentene or CFC-12. The polystyrene beads 

are produced by polymerizing styrene in a water suspension and 

adding it to a volatile liquid such as n-pentane. That serves as 

the blowing agent. The beads typically contain 5 to 7 weight 

percent of blowing agent. Prior to use, the beads are stored at 

temperatures below 21*C (70°F) to inhibit premature expansion.22 

A typical EPS bead manufacturing process flow diagram is 

shown in Figure 27. Normally, the beads are expanded in one step 

135 
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Manufacturing Process 
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and molded in another. The beads are first expanded to achieve 

the desired molding density (Step 1). Expansion is promoted by 

exposing the beads to a continuous flow of steam of hot air at 

temperatures of 212 to 220°F within a process unit called a preexpander. The amount of expansion is controlled by steam 

pressure and temperature and the bead feed rate." Both batch 

and continuous processes are common. The transfer of heat 

vaporizes the volatile hydrocarbon trapped in the polystyrene 

matrix. As the volatiles are released from the matrix, the beads 

foam and expand. 

Following the expansion process, the excess moisture 

acquired during the steaming is eliminated with hot air ^nd the 

beads are transported to storage silos constructed of large mesh 

bags, where they are allowed to cool (Step 2). " The beads are 

allowed to age for 2 to 72 hours, during which time a portion of 

the remaining trapped volatile compounds evaporates and is 

replaced with air that diffuses into the beads. Air may be 

pumped through the beads to accelerate the aging process. 

Once aged, the beads are placed in molds and steam is used 

to expand the beads (Step 3). There are three types of molding: 

shape, block, and cup molding.22 In shape molding, a premeasured 

amount of expanded beads is fed to a preheated split cavity mold. 

The beads are exposed to steam through small holes in the mold. 

The beads undergo further expansion, become soft and molten due 

to the' transfer of heat from the steam, and fuse together under 

these conditions to form a single polymer mass. Following the 

expansion and fusing process, the mold and PSF part are cooled by 

circulating water through the mold. The mold is then opened, and 

the molded part is ejected by compressed air, mechanical pins, or 

manually. Shape-molded polystyrene foam products have densities 

ranging from 1.0 to 2.5 lb/ft3.

23 

In block molding, pre-expanded beads are molded into large 

blocks of densities from 0.8 to 1.0 lb/ft3." Following cooling 

and intermediate storage, blocks are sliced into sheets or custom 

138 
P.51 

fabricated shapes. Cup molding uses smaller beads and lower 

blowing agent content than block or shape molding. Cup density 

is over 3.5 lb/ft3." Cups are molded at a moderate temperature; 

the final product is packaged in plastic and boxed for shipping. 

Post molding operations of aging (Step 4) and fabrication 

(Step 5) are the final steps before printing and shipping of the 

product. 

Polystyrene Loose Fill Packaging— 

Polystyrene loose fill packaging is manufactured with a 

combination of extrusion and bead expansion. Recycled and new 

polystyrene are mixed with a nucleating agent and melted, as for 

extrusion. The blowing agent is injected under pressure, and the 

viscous mix is extruded, foaming as the blowing agent evaporates, 

and forming hollow strands as it exits through the die. The 

hollow strands are cut into 3/4-inch pieces. The strands are 

then steamed for further expansion, as are EPS beads. 

Intermediate aging follows, and then the strands are further 

steam expanded, dried in ovens, and aged. The density of loose 

fill is about 0.2 lb/ft3. 

.3 23 

Emissions from Polystyrene Foam Production 

No information was located in the literature on styrene 

emissions associated with these processes. The reader is 

encouraged to contact individual facilities in question to obtain 

styrene emissions data. 

139 
P.52 

i 

} REFERENCES FOR SECTION 6 

1. A. T. Kearney. Impact Analysis of the EPA Office of 

Drinking Water Proposal to Regulate Styrene. Styrene 

Information Research Center. 1989. 

2. Clark, R., et al. Potential Environmental Impact of 

Compounding and Fabricating Industries: A Preliminary 

Assessment. EPA-600/2-77-160. U. S. Environmental 

Protection Agency, Cincinnati, Ohio. 1977. 

3. Pfaffi, P., et al. Degradation Products of Homopolymer 

Polystyrene in Air. Scand. J. Work Environ. Health 4 

(suppl. 2): pp. 22-27. 1987. 

4. Hoff, A., et al. Degradation Products of Plastics: 

Polyethylene and Styrene - Containing Thermoplastics -

Analytical, Occupational and Toxicologic Aspects. Scand. J. 

Work Environ. Health 8 (suppl 2): 

p. 60. 1982. 

5. Letter and enclosure from Terri Thomas, Ventura County 

Resource Management Agency, California, to D. Campbell, 

Radian Corporation. 

June 27, 1989. ' 

6. Sprow, T. K. Unsaturated Polyester. Modern Plastics 

Encyclopedia. pp. 48-50. 1986-1987. 

7. U. S. Environmental Protection Agency. Compilation of Air 

Pollutant Emission Factors. AP-42. U. S. Environmental 

Protection Agency, Research Triangle Park, North Carolina, 

p. 4.12-1 - 4.12-12. 

8. Randazzo, C , SPI Composites Institute. Comments on draft 

"Locating and Estimating Air Emissions from Sources of 

Styrene" document. December 1990. 

9. Stockton, M. B. and I.R. Kuo. Assessment of VOC Emissions 

from Fiberglass Boat Manufacturing. EPA-600/2-90-0019. 

U. S. Environmental Protection Agency, Research Triangle 

Park, North Carolina. 1990. 

10. Gibbs and Cox, Inc. Marine Design Manual for Fiberglass 

Reinforced Plastics. McGraw-Hill Book Company, New York, 

New York. pp. 4-16. 1960. 

11. Thomas Register of American Manufacturers, Thomas 

Publishing Company, New York, New York. 1987. 

12. Rogozen, M. B. Control Techniques for Organic Gas Emissions 

from Fiberglass Impregnation and Fabrication Processes. 

California Air Resources Board Report No. ARB/R-82/165. 

1982. 

14Q 
P.53 

13. Randazzo, C., SPI Composites Institute. Comments on draft 

"Locating and Estimating Air Emissions from Sources of 

Styrene" document. August 1991. 

14. Rogozen, M. B. Development of an Inventory of Styrene 

Emissions from Polyester Resin/Fiberglass Fabrication in 

California. In: The Air Pollution Control Association, ed. 

A Specialty Conference on Emission Inventories and Air 

Quality Management. April 27-30, Kansas city, Missouri, 

pp. 363-378. 1982. 

15. Chemical Profile; Polystyrene. Chemical Marketing Reporter, 

June 20:52. 1988. 

16. Resin Report 1989. Journal of Modern Plastics, January, 

1989. 

17. Society of the Plastics Industry. Membership Directory, 

1989. 

18. U. S. Environmental Protection Agency. Industrial Process 

Profiles for Environmental Use: Chapter 10. Prepared by 

Radian Corporation, 1987. 

19. Thomas Register of American Manufacturers. Thomas 

Publishing Company, New York, New York. 1988. 

20. Kirk-Othmer Encyclopedia of Chemical Technology. 3rd ed. 

Styrene Polymers. Volume 16. John Wiley and Sons. New 

York, New York. pp. 148-245. 1979. 

21. Foundation Design Handbook: Volume 1. Undercurrent Design 

Research. Underground Space Center, University of 

Minnesota. 

22. Rodriquez, F. Principles of Polymer Systems. McGraw-Hill, 

Inc., New York, New York, 1970. 

23. Tsitsopoulas, L. and M. Mills. Staff Report, Proposed Rule 

1175: Control of Emissions from the Manufacture of 

Polymeric Cellular Products (Foam). South Coast Air Quality 

Management District; Rule Development Division, September, 

1989. 

141 
P.54 

142 
P.55 

SECTION 7 

SOURCE TEST PROCEDURES 

Styrene emissions can be measured by several methods, five 

of which are: (1) EPA Reference Method 18, which was announced 

in the Federal Register on October 18, 1983;\ (2) NIOSH 

Analytical Method 1501 published in the NIOSH Manual of 

Analytical Methods on February 15, 1984;

2 (3) EPA Method 5040 

which was published in EPA Report No. SW-846 in November 1986;3 

(4) Compendium Method TO-14, determination of volatile organic 

compounds (VOCs) in ambient air using canister sampling;4 and 

(5) EPA Reference Method 8270.s 

EPA Reference Method 18 applies to the sampling and analysis 

of approximately 90 percent of the total gaseous organics emitted 

from an industrial source; whereas NIOSH Method 1501 applies only 

to the collection and analysis of ten specific aromatic 

hydrocarbons. A method similar to the NIOSH Method 1501 is the 

American Society for Testing and Materials (ASTM) D 3686-84 

method (published on June 29, 1984).6 EPA Method 5040 applies to 

the analysis of TENAX® and TENAX®/charcoal cartridges used to 

collect volatile principal organic hazardous constituents (POHCs) 

from wet stag gas effluents. Compendium Method TO-14 is 

applicable to specific VOCs that have been tested and determined 

to be stable when stored in pressurized and sub-atmospheric 

pressure canister.* EPA Method 8270 is used to determine the 

concentration of semivolatile organic compounds using gas 

chromatography/mass spectrometry (GC/MS). 

EPA REFERENCE METHOD 18 

In Method 18, a sample of the exhaust gas to be analyzed is 

drawn into a Tedlar® or aluminized Mylar® bag; as shown in 

Figure 28. The bag is placed inside a rigid, leakproof;container 

143 
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P.57 

and evacuated. The bag is then connected by a Teflon® sampling 

line to a sampling probe (stainless steel, Pyrex® glass, or 

Teflon®) at the center of the stack. The sample is drawn into 

the bag by pumping air out of the rigid container. 

The sample is then analyzed by gas chromatography (GC) 

coupled with flame ionization detection (FID). Based on field 

and laboratory studies, the recommended time limit for analysis 

is within 30 days of sample collection.7** The GC operator should 

select the column and GC conditions that provide good resolution 

and minimum analysis time for styrene. Zero helium or nitrogen 

should be used as the carrier gas at a flow rate that optimizes 

the resolution. 

The peak areas corresponding to the retention times of 

styrene are measured and compared to peak areas for a set of 

standard gas mixtures to determine the styrene concentrations. 

The detection limit of this method ranges from about 1 part per 

million (ppm) to an upper limit governed by the FID saturation or 

column overloading. However, the upper limit can be extended by 

diluting the stack gases with the inert gas or by using smaller 

gas sampling loops. 

When access to the sampling location is difficult, an 

alternative sampling method described in Section 7.4 of EPA 

Reference Method 18 may be preferred.* 

NIOSH METHOD 1501 

, This method has limited application. . The method applies 

only to ten specific aromatic hydrocarbons. Several necessary 

modifications are. recommended if this method is to be used.9 

In the NIOSiH method, samples are collected with solid 

sorbent tubes containing coconut shell charcoal. Five to 14-

liter air samples are collected with the use of a personal 

sampling pump at a known flow rate of < 1 L/minute.2 

145 
P.58 

Samples are desorbed with carbon disulfide and analyzed by 

GC equipped with an FID and a column capable of resolving styrene 

from the solvent front and other interferences. The column 

specified in NIOSH Method 1501 isa3.0mx2m m glass or 

stainless steel, 10% OV^275 on 100/120 mesh Chromosorb® W-AW, or 

equivalent.2 

The amount of styrene in a sample is obtained from the 

calibration curve in units of milligrams per sample, storage 

stability has not been assessed for this method, thus, analysis 

should occur as soon as possible following sample collection. 

Styrene can dimerize during handling and storage. The" rate of 

dimerization is a function of temperature, increasing as the 

temperature increases. Consequently, samples should be stored at 

low temperatures. 

This procedure is applicable for monitoring styrene air 

concentrations .ranging from 2.17 to 8.49 mg. The GC column and 

operating conditions should1 provide good resolution and minimum 

analysis time. 

EPA METHOD 5040 

In Method 5040, a sample of stack gas is collected on TENAX® 

and T.ENAX®/charcoal sorbent cartridges using a volatile organic 

sampling train, (VOST).3 Because the majority of gas streams 

sampled using VOST will contain a high concentration of water, 

the analytical method is based on the quantitative thermal 

desorption of volatile POHCs from the TENAX® and TEN.AX®/charcoal 

traps. The analysis is by purge-and-trap GC/MS. 

A schematic diagram of the analytical system is shown in 

Figure 29. The contents of the sorbent cartridges are spiked 

146 
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CO 
P.60 

with an internal standard, thermally desorbed, and trapped on an 

analytical adsorbent trap directed into the GC/MS. The volatile 

POHCs are separated by temperature-programmed GC and detected by 

low-resolution mass spectrometry. 

The concentrations of volatile POHCs are calculated using 

the internal standard technique. Sample trains obtained from the 

VOST should be analyzed within two to six weeks of sample 

collection. The desired target detection limit of this method is 

0.1 ng/L (20 ng on a single pair of traps). Industry experience 

has found this method to be difficult to use and easily 

overloaded when the analyte concentration is in the high parts 

per billion (ppb) to ppm range.10 In addition, the cost" 

associated with this method is higher than other analytical 

methods.* 

COMPENDIUM METHOD TO-14 

Method TO-14 is based on collection of whole air samples in 

SUMMA® passivated stainless steel canisters for analysis of 

volatile organic compounds (VOCs) in ambient air. A sample of 

ambient air is drawn through a sampling train composed of 

components that regulate the rate and duration of sampling into a 

pre-evacuated SUMMA® passivated canister. 

The VOCs are separated by GC and measured by mass-selective 

detectors or multidetector techniques. The recommended time 

limit for analysis is within 14 days of sample collection.10 The 

column specified in Compendium Method TO-14 is a Hewlett OV-1 

capillary column, 0.32 mm I.D. x 50 m with 0.88 um cross-linked 

methyl silicone coating, or equivalent.4 The wider J & W 

Scientific Company Megabore® column (i.e., 0.53 mm I.D.) can be 

used as long as the system meets user needs.4 Compounds have 

been successfully measured at the parts per billion by volume 

(ppbv) level using this method. 

148 
P.61 

This method is designed for ambient, not source monitoring. 

Few laboratories offer it and it is quite costly. It is 

reportedly difficult to use and the sample may be easily 

contaminated by the system. Recovery rates for reactive 

compounds tend to be very low.' 

EPA REFERENCE METHOD 8270 

Method 8270 describes conditions for GC/MS and is used to 

determine the concentration of semivolatile organic compounds in 

extracts prepared from all types of solid waste matrices, soils, 

and ground water. The analytical methodology will be equally 

applicable to an extract from sorbent media used in conjunction 

with EPA Method 0010 to sample stationary sources. The sorbent 

for Method 0010 is XAD-2® resin which is a styrene-divinylbenzene 

copolymer. Styrene monomer may also be present in the resin and 

may result in interferences. A different sorbent should be, 

substituted for XAD-2®. Two possible candidates are TENAX®, 

which would require extraction with pentane or hexane, and XAD-7® 

which is an acrylic resin. Extraction efficiencies would need to 

be validated before these modifications are accepted. 

Styrene is within the boiling point range for analysis by 

Method 8270, but is sufficiently volatile. Care must be taken in 

sample concentration to avoid loss. An adjustment in 

chromatographic conditions will be required to resolve the 

relatively volatile styrene from the solvent. 

The practical quantitation limit for Method 8270 is 

approximately 50 ug/mL of extract. The entire sorbent module 

with filter is typically extracted and concentrated to a final 

volume of 1 mL. This final extract volume represents the entire 

volume of gas sampled. 

149 
P32^ 

REFERENCES FOR SECTION 7 

1. 40 CFR Part 60, Appendix A, Method 18: Measurement of 

Gaseous Organic Compound Emissions by Gas Chromatography, 

pp. 868, 873-878, 886, 889, 895. July 1, 1989. 

2. U. S. Department of Health, Education, and Welfare. NIOSH 

Manual of Analytical Methods, 3rd ed., Volume 2. Nationkl 

Institute for Occupational Safety and Health, Cincinnati, 

Ohio. pp. 1501-1 to 1501-7. 1984. 

3. Method 5040: Protocol for Analysis of Sorbent Cartridges 

from Volatile Organic Sampling Train. Test Methods for 

Evaluating Solid Waste, 3rd ed., Vol. IB: Laboratory 

Manual, Physical/Chemical Methods. EPA Report No. SW-846. 

November 1986. 

4. Compendium Method TO-14: The Determination of Volatile 

Organic Compounds (VOCs) in Ambient Air Using Summa® 

Passivated Canister Sampling and Gas Chromatographic 

Analyses. Quality Assurance Division. Atmospheric Research 

and Exposure Assessment Laboratory, U. S. Environmental 

Protection Agency, Research Triangle Park, North Carolina, 

pp. 1-15, 18,19, 21-23. May 1988. 

5. U. S. Environmental Protection Agency, Office of Solid Waste 

and Emergency Response. Method 8270: Gas Chromatography/ 

Mass Spectrometry for Semivolatile Organics: Capillary 

Column Technique. Test Methods for Evaluating Solid Waste, 

3rd ed. Report No. SW-846. Washington, D.C. 1986. 

6. ASTM D3686-84. .Annual Book of ASTM Standards, Volume 11.03. 

1984. 

7. Personal Communication.l- Moody, T. K., Radian Corporation, 

with Hartman, M., Radian Corporation, October 9, 1989. 

Discussion of styrene/butadiene stack sampling and analysis. 

8. Personal Communication. Moody, T. K., Radian Corporation 

with Pau, J., U. S. Environmental Protection Agency, 

Atmospheric Research and Exposure Assessment Laboratory, 

October 10, 1989. Discussion of EPA Reference Method 18 in 

relation to styrene stack sampling. 

9. Randazzo, C.,. SPI Composites Institute. Comments on draft 

"Locating and Estimating Air Emissions from Sources of 

Styrene" document. December 1990. 

10. Personal Communication. Moody, T. K., Radian Corporation, 

with Rice, J., Radian Corporation, February 7, 1990. 

Discussion of Compendium Method TO-14. 

150 
P.63 

TECHNICAL REPORT DATA | 

(Please read Instructions on r*# reverse before completing) 

I. REPORT NO; 

4. TITLE ANO^STITL E 

2. 

Locating and Estimating Air Emissions From 

Sources of Styrene, Interim Report 

7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NQ. 

Darcy Campbell 

9. PERFORMING ORGANIZATION NAME ANO ADDRESS 

Radian Corporation 

Post Office Box 13000 

Research Triangle Park, North Carolina 27709 

3. RECIPIENT'S ACCESSION NO. 

5. REPORT OATE 

October 1991 

6. PERFORMING ORGANIZATION CODE 

10. PROGHAM ELEMENT NO. 

1. CONTRACT/GRANT NO. 

68-DO-012 5 

12. SPONSORING AGENCY NAME ANO AOORESS 

Technical Support Division 

OAR, OAQPS, TSD, EFMS (MD-14) 

Emission Inventory Branch 

P^^TT- H TytamyiP Park. North Carolina 27711 

13. TYPE OF REPORT ANO PERIOO COVERED 

Tnt-p-i- i in 

14. SPONSORING AGENCY CODE 

IS. SUPPLEMENTARY NOTES 

EPA Project Officer: Anne A. Pope 

16. ABSTRACT . 

To assist groups interested in inventorying air emissions of various 

potentially toxic substances, EPA is preparing a series of documents 

such as this to compile available information on sources and emission 

of these substances. This document deals specifically with styrene. 

Its intended audience includes Federal, State and local air pollution 

personnel and others interested in locating potential emitters of 

styrene and in making gross estimates of air emissions therefrom. 

This document presents information on (i) the types qf sources that 

may emit styrene, (2) process variations and release points that may 

be emitted within these sources, and (3) available emissions 

information indicating the potential for styrene releases into the air 

from each operation. 

This document is being released as an interim document pending 

incorporation of testing results from the U.S. EPA. The EPA is 

currently testing several unsaturated polyester resin fabricators who 

produce cultured marble bathroom fixtures. When the test results are 

iilablo, tha FPA will publish a final report inclurling th^se data. -av-a; 

17. KEY WOROS ANO OOCUMENT ANALYSIS 

DESCRIPTORS b,IOENTIFIERS/OPEN ENOEO TERMS C. COSATI Field/Group 

Styrene 

Air Emissions Sources 

Locating Air Emissions Sources 

Toxic Substances 

18. DISTRIBUTION STATEMENT 19. SECURITY CLASS (Tltis Reportf 2 1 . NO. OF PAGES 

Unlimited 20. secuyrrgtBBgiiltWtfli 

Unclassified 

22 .pnit6; 

EPA F«« M 2220-1 (R«v. 4-77) previou s COITIO N I S OBSOLET E