p.1 

OAR Box 1413 

Prepped by Ollie Stewart 

Document Number: 

19)11-1-19 

Docket Number: 

A-94-52 

Printed 7/9/2008 3:11:21 PM Sheet 19 of 114 
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TECHNICAL INFORMATION 

^.ft^Htf^iooW ^ Jt-94-52 

OowPtastfcs 

THERMOSET POLYMERS 

Polyurethanes, 

Epoxies, 

VinjiEster 

and High 

Reduction of Styrene Emissions for Filament Winding Operations

 FerfafeIE 

I !• 

Don H. Kelley 

LJ. Craigie 

G.L. Webster 

RL. Wykowski 

The Dow Chemical Company 

2301 N. Brazosport Blvd. 

Freeport, TX 77541 

Abstract 

Two of the hottest topics in the Fiberglass-Reinforced Plastic (FRP) industry today are 

styrene emission and personnel exposure reduction. These are the result of clean air 

regulations and changing guidelines concerning safe exposure levels. Within a fiberglass 

shop, open molding operations such as hand lay-up, spray-up and filament winding are 

considered major contributors to styrene emissions. This paper reviews a study conducted 

to determine the effect of selected resin properties and operating conditions on emissions 

from filament winding operations. 

Introduction 

By 1997, the Clean Air Act Amendments will require the Environmental Protection 

Agency (EPA) to develop maximum achievable control technology (MACT) standards for 

styrene emissions generated by the composite plastics industry 1. These standards would 

be used as minimum guidelines for state enforcement Styrene emissions to the air can be 

reduced by source reduction or abatement Source reduction has the advantage of also 

reducing personnel exposure and, if achievable through operation procedure changes or 

resin chemistry, would be the preferred method of reducing emissions. 

The present studies were designed to measure the effect of selected variables on point 

source reduction as opposed to emission capture and treatment The purpose of this 

paper is to discuss two experimental design studies that identified air flow, styrene 

content and suppressant level as significant effects for styrene emissions from a laboratory 

filament winding process. 

NOTICE: This infortnatioo is presented in good faith. No warranty expressed or implied, is given nor is freedom from any patent owned by The Dow Chemical Company or by others to 

be inferred. Inasmuch as any assistance furnished by Dow with reference to the proper use and disposal b provided without charge, Dow assumes no obligation or Gability therefore. 

Read, understand, and/or practice the information printed on product Material Safety Data sheets prior to use of any Dow product 'If products are discribed as 'experimental": quality 

specs may not b<* fully determined; analysis of hazards and caution in handling and use are required: Dow reserves the right to change s^cification a H 'or discontinue production 

I 
P.3 

Experimental Procedure 

The experimental approach was to choose five resin and operational variables that could 

potentially effect styrene emissions fiom a filament winding process using styrene diluted 

unsaturated thermosetting resin. Screening experiments were then conducted to detennine 

if these variables were significant effects. 

Table 1 shows the five variables that were chosen for the first experiment and the levels 

that were studied. The variables were temperature, air flow, styrene content of the resin, 

styrene suppressant, and gel time. Fbr screening purposes, a two level fractional factorial 

experimental design was chosen as shown in Table 2*. 

The experimental set up is shown in Figure 1. The equipment consisted of a filament 

winding machine, with a 3 ft diameter by 6 ft long mandrel, which was located under a 

12 by 12 ft pyramidal hood with a one ft diameter vent stack on top. A^lQor*_to_ceiling 

plastic curtain was placed around the outside edge of the hood for the first experiment 

Passive dosimeters* were placed in specified areas to measure styrene levels. They were 

placed over the resin bath(expected to be the highest styrene levels), near the mandrel on 

the side opposite the resin bath (representing operation personnel), immediately outside 

the curtain(to measure background styrene levels), and in the vent stack four diameters 

from the intake opening to measure emissions. Also, a charcoal tube dosimeter was 

placed in the same region as the passive dosimeter in the stack. 

The vent stack was equipped with a damper to control the air flow. Ihe air flow was 

measured at three damper settings according to EPA 40 CFR Ch.l, Pt 60, App. A, 

Method 1. The temperature and air flow were set prior to winding. Cobalt naphthenate 

(CoNap), dimethyl analine (DMA) and suppressant (Experimental Epoxy Vinyl Ester 

Resin Additive XUS-71998.00) were premixed into 22 pounds of resin. fi£teea>pounds of 

resin were catalyzed and 5 pounds of die catalyzed resin„were placed intiirs*esin bath.-. 

The mandrel was rotated at 20 revolutions per minute. Catalyzed resin was added to the 

bath as needed. The remaining ?,pounds of resin was later catalyzed and added to tiie 

bath as needed. 

After the resulting cylinder reached a specified thickness, the winding was stopped and the 

dosimeter over the bath was removed. Once the resin gelled and reached peak exotherm, 

the other dosimeters were removed, and all were sent to analytical services for styrene 

content determination. Once the laminate had cured, the cylinder was removed, weighed, 

and samples were cut out for glass content determinations. 

The amount of styrene adsorbed by the dosimeters was determined by adding 1.5 

milliliters of carbon disulfide to the dosimeter and letting it stand for 1/2 hour with 

occasional gentle agitation. The carbon disulfide was then transferred to a gas 

chromatograph (GC) to determine the amount of styrene desorbed by the extraction. The 

micrograms of styrene determined by the GC were used to calculate tiie time weighted 

average (TWA) of styrene detected by the dosimeter in part per million (ppm). 

z 
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A 4-factor, two level half-fractional factorial screening experiment, as shown in Table 3, 

was chosen for the second experiment^. The factors and tiieir levels are shown in Table 4. 

The experimental procedure was sjrailarjo exMrimentl, ex^t|^|(5otal«hclestiie 

(TE^was built around the filament winder and aJOGfe ' 

emissions in the stack in addition to a passive dwlmeter^and.charwwl-tube. The TB, 

shown in Figure 2., was based on aii EPA design described in EPA 450/4-91-020. The 

TE was equipped with 3 natural draft openings (NDO) at the bottom of three sides. The 

hood and vent stack from experiment 1 were utilized. However, passive dosimeters were 

not used to monitor the bath or to simulate worker exposure. Also, a manometer was 

used to monitor the air flow in the stack. 

The GC was calibrated with a standard gas composed of 50 ppm styrene and 50 ppm ethyl 

benzene. The standard was run through the sample valve at 3 minute intervals until the 

area responses were stable. The integrator was tiien calibrated to the response factors 

based on the standaid gas. During winding, an air sample was drawn from the stack and 

through the GC sample valve every three minutes. The styrene concentration in ppm was . , ; . 

obtained from a print out provided by the integrator. -j-y Rr X 33%S7Y =-* " ° . ." 

In experiment 2, winding was continued until the layers were approximately one fourth<of 

an inch thick. A total of 22 pounds resin was formulated andx»t*flyzed for the 40 minute 

geltime. FbrtheS minute gel time, a fast gelling formulation wasadded to the resin bath 

5 minutes before winding was stopped. The passive dosimeter and the charcoal tube were 

not removed from the stack until die gas chromatograph indicated the styrene level had 

reached zero. 

The styrene concentration in the stack was determined every 3 minutes with the gas 

chromatograph. The passive dosimeters were sent to an analytical laboratory for styrene 

content determinations. The following formulas were used to calculate the time weighted 

average (TWA) of the styrene concentration for the respective measuring device: 

Gas Chromatography 

TWA emissions, ppm = total styrene in ppm/ total number of samples 

Passive Dosimeters 

TWA emissions, ppm = (styrene in ug x 8.77 min/g)/ 

(0.92 x time in minutes)** 

Charcoal Tube 

3 
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TWA emissions, ppm = (styrene in ug x 235 cc/g)/ 

(0.76 x time in rain x 200 cc/min) 

The TWA of the styrene concentration was used to estimate the total styrene emissions. 

To convert the styrene concentration to total pounds, the following formula was used: 

Total styrene emissions, lbs = 

(TWA styrene emissions in cc/ra** x air flow in m^/min x time in min. 

x 104 g/raole)/ (24.451/raole x 1000 cc/1 x 454 g/lb)4 

A statistical software program, JMP 2.0.5 from the SAS Institute in Cary, North Carolina, 

was used to analyze the data for effects and significance. 

Results 

The results of the first experiment are shown in Tables 5,6,7 and 8. For the analysis, run 

number one was not used, because the resin bath gelled before the specified thickness was 

reached causing the emission levels to be lower than expected. 

Table 5 shows the time weighted average (TWA) emissions in ppm for the badges over 

the bath and in front of the winder for each run. The pounds of emissions measured in the 

stack with both the badge and charcoal tube are also in Table 5. The data shows that 

there was difficulty with the charcoal tube apparatus. This may have been due to the 

vibrations in the stack breaking the seal between the charcoal tube and die pump. This 

would prohibit the stack gas from being drawn through the filter. 

Table 6 shows the statistical significance of each variable on the emissions over the bath. 

The F ratio is the model mean square divided by the error mean square. If a parameter is a 

significant effect in the model, the F Ratio is higher than expected by chance alone. 

Having a high F ratio, the temperature and the airflow were significant effects for the 

styrene concentration over the bath. 

Prob>F is the observed significance probability of obtaining a greater F value by chance 

alone if the specified model fits no better than the overall response mean. For die 

purposes of this study, observed significance probabilities of 0.15 or less were considered 

significant With Prob>F of 0.8566 and 0.4112 respectively, the styrene concentration in 

the resin and the use of suppressant were not statistically significant effects. 

Figures 3 and 4 are leverage plots showing the effect of temperature and air flow on the 

styrene emissions over the bath. The lines represent the relative change in emissions over 

the range of change of the air flow and temperature. The dotted lines are confidence 

curves for the model. An effect is significant if the confidence curve crosses the line which 

is the mean value. As shown in Fig. 3, the styrene concentration measured over the bath 
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increased as the temperature increased. On the other hand, the styrene concentration 

decreased as the air flow increased as shown inHg. 4. ... . .. ... 

Similar results were obtained with the dosimeter that was used to simulate a workers 

exposure as shown in Table 6. The styrene concentration increased with temperature and 

decreased widi air flow. Again the styrene content of the resin and die use of suppressant 

did not affect the styrene concentration as measured by the dosimeter used to simulate a 

woricer standing in front of die mandrel. This was probably due to die constant placement 

of fresh resin on the mandrel surface during filament winding. 

MI.SSIN/6 F_*>y£t> 5 AND&[ 

As the air flow increased, styrene' 

emissions increased. As the styrene content of the resin decreased, Hg. 6, die styrene 

emissions decreased. Table 8 shows that styrene emission levels were responsive to the 

styrene content of the resin, die suppressant and the air flow, but die temperature and die 

gel time had no affect on emissions. 

A second experiment was conducted because it was believed that more frequent 

monitoring of emissions during filament winding would give more insight into how to 

reduce emissions from the filament winding process. This was accomplished by 

monitoring the stack gas widi a gas chromatograph which sampled every three minutes. 

The results from measuring the styrene concentration in die stack gas versus time is shown 

in Rgure 7. It shows the styrene concentration versus time for runs 7 and 8. Run 7 had a 

slow gel time and run 8 had a fast gel time. In Figure 7, note that most of the styrene was 

emitted during the winding. Once the winding was completed, die styrene concentration 

fell sharply and continued at a much lower level becoming zero within 60 minutes. 

The knowledge that diere was a sudden change in styrene concentration, when the 

filament winding stopped, became useful for the statistical analysis. By analyzing die 

affect of the variables during and after winding, die significance of each variable became 

more obvious than measuring emissions over the entire period of die winding process. 

Table 9 shows die emissions before and after winding for each run. For most of the runs, 

over 80% of die emissions occurred during winding. Run 2 which had low air flow, low 

styrene, suppressant and a fast gel time had the lowest emissions both during and after 

winding. Run 7 which had high air flow, high styrene, no suppressant and a long gel time 

had the highest emissions botii during and after winding. 

Tables 10 and 11 show die statistical significance of die experimental variables on styrene 

emissions during and after winding. The high F ratios for the styrene content and die 

suppressant indicate that diey had the greatest effect on the styrene emissions during 

winding. In bodi cases, the analysis (Prob>F) showed diat there was over a 98% chance 

tiiat these were real effects. With a Prob>F of 0.1135, the air flow had nearly an 88% 

chance of being a significant effect 

5 
P.7 

After winding was completed the significant emission effects were different as shown in 

Table 11. Witii a prob>F of 0.0058, die gel time had over a 99% probability of being a 

significant effect and the styrene content (prob>F 0.0563) of the resin had a 94% 

probability of being significant The air flow and suppressant did not significantly affect 

emissions after the winding stopped. 

During filament winding the styrene concentration in the air apparently reached a steady 

state which is controlled by die introduction of fresh resin on the surface. Once the 

winding stopped, the styrene concentration dropped to the equilibrium that was 

established by the surface. 

Conclusions 

1. Of the stack emissions which were measured, oyer80%OcCttred durirtg-*thtf-Winding 

.process. 

2. Stack emissions after winding accounted for less than 20% of the styrene emitted. 

3. Continuous monitoring of stack emissions via gas chromatography greatly aided in 

understanding the process and analyzing the data. 

4. The stack emissions measured during winding were significantly effected by the air 

flow, the styrene content of the resin, and die use of suppressant 

5. Stack emissions after winding were significantiy effected by the styrene content of the 

resin and the gel time. 

6. Styrene emissions measured over the bath and emissions simulating a personnel 

exposure were significantly effected by the temperature and air flow. 

Acknowledgments 

The authors wish to thank Dr. Stanley Deraing for his useful and enlightening 

consultations. 

Notice 

The information in this publication is presented in good faith, but no warranty is given, 

express or implied, nor is freedom from any patent to be inferred. 
P.8 

References 

1. John Schweitzer, The Society of the Plastics Industry, Inc., private communication 

2. U.S. Environmental Protection Agency. Compilation of Air Pollutant Emission 

Factors. AP-42. U.S. Environmental Protection Agency, Research Triangle park, North 

Carolina, September, 1985. 

3. Donald J. Wheeler, Tables of Screening Designs, Second Edition, (Knoxville, 

Tennessee: SPC Press, Inc., 1989), p. 19. 

4. 3M Organic Vapor Monitors #3500/3510: Instructions for Use. Occupational Health 

& Safety Products Division/3M, The 3M Company, St Paul, Minnesota. 

5. Stephen W. Edgerton et al., "The Measurement Solution," United States 

Environmental Protection Agency (EPA), EPA-450/4-91-020, August 1991. 

1 
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TABLE4.^EXPERIMENT 1VARIABLE AND LEVELS 

NUMBER 

1 

2 

3 

4 

5 

VARIABLE 

Temperature 

Air How 

Styrene Content 

Suppressant Level 

Gel Time 

UNITS 

" 

op 

CFM 

* 

% 

Minutes 

LOW LEVEL 

(-1) 

70 

500 

33 

0 

40 

HIGH LEVEL 

(+1) 

88 

3,000 

50 

1.5 

90 

TABLE 2. EXPERIMENT1 DESIGN 

RUN 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

STYRENE 

+ 

+ 

-

+ 

-

+ 

-

-

+ 

+ 

+ 

+ 

TEMPERATURE 

-

+ 

-

-

+ 

+ 

-

+ 

-

-

-

+ 

AIR 

FLOW 

+ 

-

-

-

+ 

+ 

+ 

-

-

-

-

+ 

GEL 

TIME 

-

-

-

+ 

-

+ 

+ 

+ 

-

-

+ 

+ 

SUPPRESSANT 

+ 

-

-

+ 

+ 

-

-

+ 

-

-

+ 

-

TABLE 3. EXPERIMENT 2 DESIGN 

RUN 

1 

2 

3 

4 

5 

6 

7 

8 

AIRFLOW 

-

-

-

-

+ 

+ 

+ 

+ • 

STYRENE 

-

-

+ 

+ 

-

-

+ 

+ 

SUPPRESSANT 

-

+ 

-

+ 

+ 

-

-

+ 

GELTIME 

-

+ 

+ 

-

-

+ 

-

+ 

% 
// 

P.10 

TABLB4.vEXEERIMENT 2 VARIABLES AND LEVELS 

NUMBER VARIABLE UNITS LOW HIGH 

LEVEL (-1) LEVEL (+1) 

1 Air How 

2 Styrene Content 

3 Suppressant 

4 Gel Time 

CFM 

% 

% 

MINUTES 

1600 

33 

0 

40 

3000 

50 

1.5 

TABLE 5. STYRENE EMISSIONS BY LOCATION AND METHOD IN 

EXPERIMENT 1 

RUN BATH TWA 

NUMBER EMISSIONS, 

^s-ay 

fO 1 

50 2 

-J3 3 

SO 4 

1 3 5 

S3 6 

Ti 7 

3* 8 

ss 9 

^< 10 

so n 

5-5 12 

PPM 

ftV/.A:-LAft'" 

LK,: ' DOSIMETER 

<< 312 

" 1703 

X2C. 945 

»

l

 857 

"•*- 445 

'i 933 

1

-'-~ 303 

' ~ 1511 

'• 489 

'•• 82 4 

i;

 855 

744 

FRONT 

TWA 

EMISSIONS, 

PPM 

DOSIMETER 

49 

524 

163 

166 

133 

109 

42 

462 

112 

264 

73 

136 

STACK"* »• STACK 

EMISSIONS, EMISSIONS, 

LBS." *I_BS; 

CHARCOAL 

DOSIMETER 

1.94 

3.28 

2.35 

2.55 

3.35 

4.56 

3.19 

1.5 

2.86 

3.28 

3.63 

4.54 

i7.fe 

•2*1-6 

32-4 

-2.1."2* 

4b-i 

^l.-S" 

43. =1 

2.0.7 

2o.o 

2

;

: -

"^*** ~-

4 ••. i 

TUBE 

1.09 <\A 

3.35 W ; 

2.77 *B.i 

2.96 2<-.*. 

nil — 

nil — 

2.64 3i--i 

1.56 2i.-r 

nil — 

1.6 8 '-:•• 

4.2 8 :•• 

rai — 

AV4 r "*>1- l 

TABLE 6. THE SIGNIFICANCE OF THE FACTORS 

ON STYRENE EMISSIONS OVER THE BATH 

2 1 . Z INK." K/oT 

AVC *. 

FACTOR 

Styrene 

Temp. 

Air How 

Supp. 

F RATIO 

0.0356 

31.3895 

29.2179 

0.7798 

PROB > F 

0.8566 

0.0014 

0.0017 

0.4112 

SIGNIFICANT? 

No 

Yes 

Yes 

No 
P.11 

TABLE 7. THE SIGNIFICANCE OF THE FACTORS ON STYRENE 

EMISSIONS FOR THE SIMULATED WORKER EXPOSURE FOR EXP. 1 

FACTOR F RATIO 

Styrene 

Temp. 

Air Flow 

Supp. 

Gel Time 

0.3480 

16.0142 

12.5564 

0.6392 

_XUU25_ 

PROB>F 

0.8809 

0.0103 

0.0165 

0.4603 

0.7154 

~/ff f.et>vc-t 

SIGNIFICANT? 

No 

Yes 

Yes 

No 

-2J5.0 

TABLE 8. THE SIGNIFICANCE OF THE FACTORS ON STYRlENE 

EMISSIONS IN THE STACK FOR EXP. 1 

FACTOR F RATIO PROB>F SIGNIFICANT? 

Styrene 

Temp. 

Air How 

Supp. 

Gel Tung, 

10.2084 

0.1111 

24.0020 

6.8186 

,0.41.13-

0.0241 

0.9932 

0.0045 

0.0045 

/<_ R.&t"-''-T 

Yes 

No 

Yes 

Yes 

-NOLOW STVR£NE 

2-8, 

VJT C,l,Ox.a 

.v.o_j Cter*; 

H_.ouj $*£ $ 

RUN 

COMPARISON OF STYRENE EMISSIONS 

DURING AND AFTER WINDING 

<=£> DURING, LBS AFTER, LBS TOTAL 

~" 1 

t o 2 S 

uc 3 

LC* 4S 

-• - 5S 

6 

7 

MS 8S 

1.79 

1.61 

2.46 

1.97 

1.61 

2.01 

3.15 

2.14 

0.44 

0.12 

0.28 

0.58 

0.55 

0.13 

0.82 

0.27 

33 

33 

5 0 

-So 

33 

33 

5<9 

2.23 

1.73 

2.74 

2.55 

2.16 

2.14 

3.97 

2.41 

"7.2* 

l.Z'o 

VI.' 1 

i l . J 

7. 

"?-?'-

l O 

n.;: 

Ef*V$. 

3s .1 

24-i 

23.1 

36>.\ 

A v •;- 2. / .•**-

TABLE 10. STATISTICAL SIGNIFICANCE OF STACK EMISSIONS DURING 

WINDING FOR EXP. 2 

-7. 5 

FACTOR F RATIO PROB>f SIGNIFICANT? 

Styrene 

Air How 

Supp. 

21.4504 

3.6721 

12.9047 

0.0057 

0.1135 

0.0157 

Yes 

Yes 

Yes 

1° 
P.12 

TABLE 11. STATISTICAL SIGNIFICANCE OF STACK EMISSIONS AFTER 

WINDING FOR EXP. 2 

FACTOR 

Styrene 

Air How 

Supp. 

Gel Time 

F RATIO 

7.0811 

2.410 

0.8789 

28.8308 

PROB > F 

0.0563 

0.1954 

0.4016 

0.0058 

SIGNIFICANT? 

Yes 

No 

No 

Yes 

ll 
P.13 

Figure 1. Schematic of filament winding experiment 1 

Figure 2. Total enclosure around filament winder 

I*-
P.M 

Figure 3. The effect of temperature on styrene 

concentration (ppm) over the bath 

I. 

a. thTWA 

.2 

1 7SO 

1 SOO -

1250 -

1000 -

7SO -

500 -

• 

6 5 

. 

•"*" " __-^ 

y' ^^ 

y' 

* i 1 i i i 7 0 7 5 8 0 SS SO GS 

Temp.. *F Leverage 

Figure 4. The effect of air flow on the styrene 

concentration (ppm) over the bath 

t= 

& 

1 

cS 

*l zso 

i soo -

1250 -

1 ooo -

7SO -

soo2SO—| 

*•»» , 

> v v% 

"**» ^^^_ **. 

*"**-- . ^^" ^ **•* » 

***-. ^S s v_ *•** 

***• * ^* s- ^ _ "***- . 

i i i 

•1 oo o O IOO O 200 0 

Air Flow, cf m Leverage 

300 0 

|3 

_J 
P.15 

Figure 7. Styrene emissions vs time for filament winding 

3 12 21 JO 33 4S 57 « 7S M «3 102 111 120 129 138 147 ISS 16S 

Time, min 

I *