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## Document

Number: 

# 6 ) 11-1- 6
Docket Number: 

# A-94-5 2

Printed 7/9/2008 3:11:20 PM

Sheet 6 of 114P. 2

AU G 3 1 '9 5 11:43A

M EP ADURHA M

> ' . _ . l

•y $

>->• * 

# '-^'J? ^ P . 2/ 5 A .

> v 

# Emissio n o

f .Styren e Durin g th e Han d Lay-U p Moldin g o

f Reinforce d Polyeste r
Art o J . Slimanen, * Ralm o I

. Niemeia, 6 Tuul a K . Blomqvist, c an d Eev

a M . NIKander

4 Technica l Researc h Centr e o f Finland , Safet y Engineerin g Laboratory , P.O

. Bo x 656 , SF-3310 1 Tampere , Finland ; "Institut e o f Occupationa l Health , Departmen t of Industria l Hygien e an d Toxicology , Laajaniitynti e 1 , SF-0162 0 Vantaa , Finland ; c Nest e Chemicals , Polyester , P.O

. Bo x 320 , SF-0610 1 Porvoo , Finlan d

Th e emissio n rate s o f

styren e monomer fro

m standar d an d low styrene-eraissio n (LSE

) resins were determined durin g th e han d lay-u p moldin g o f

reinforce d polyester . Th e evaporation test s wer e carried our i n controlle d laborator y condition s b

y .__.ir_ g 0.16 S m 2 laminate . Th e emissio n rat e wa s highes ti n th e rolling phase , rangin g from 5

9 t o 7 9 mg/s/m* . Th e emission , rat e o f styren e with LS

E resi n wasj^| £ percentlowe r tha n tha r o f standar d resin . T^ f

y*- » nf T.S F i-p^l n reduce d th e tota l evaporation o f styrene 30-6 0 percentcompare d t o standar

d resin . Thi s I

s du e t o th e fac ttb"a

tLS E resi n ha

s a lowe r evaporatio

n rat e i n the perio d betwee n th e rollin g an d curing . Th e evaporario n rate s obtaine d b

y th e gravimetri c evaporatio n tes tdo notinclud e ch

e rollin g perio d an d shoul d notb e use d t o estimat e th e emissio n rat e o f sty-^n j i ^

-—•-• i --»ni-_---f

- opemtiom

. saamimen , AJ. ; Nlemeli

. R.L ; Biomqvist , T.K. ; Nikander , LM
- Emissio n o f Siyren e Durin g th e Han d Lay-U p Moldin g o f Reinforce d Polyester

. Appl

. Occup , Environ

. Hyg

. 6:790-793 ; 1991

.
Introductio n Durin g th e pas

t1 0 years , ih e hygieni c limit s for styrene monome r hav e bee n lowere d i n ch e Scandinavia

n coun tries . Th e presen thygieni c limiti n Finlan d (2 0 pp m 8-hour time-weighte d averag e (TWA| ) indicate s a n increasin g nee d fo r exposur e contro l measures i n th e reinforce d plastic s industry . Both th e U.S . Occupationa l Safet y an d Healt

h Administratio n 8-hou r standar d an d th e America

n Conference o f

Governmenta

l Industria

l Hygienist

s threshol d limi tvalu e fo rstyren e monome ri s a n 8-hour TW\ o f

5 0 ppm . Ventilatio n seem s t o b e on e o f

th e mos timportan

t contro l method s o f

styren e vapors." -4 ) Loca

l exhaus tven tilatio n i s t o b e preferred becaus e vapor s ar e captured a

t th e sourc e befor e dispersin g into th e laminator s breathin g zon e an d int o th e general atmospher e ofth e workin g area. By contrast

, exposure contro

l b y genera l ventilatio n i s base d o n dilutio n o f

contaminant

s belo w th e acceptabl e leve l by flushin g th e entir e workroo m wit h clean air. A

s th e emis sio n rat e o f styren e vapo r an

d it s tim e histor

y i n differen

t phase s o f th e laminatio n proces s i s insufficientl y known , however , th e basi s fo r th e calculatio n o f ventilatio n ai

r flow' s i s often inadequate , resultin g i n high concentrations o f styrene . Furthermore , dilution-ventilatio n ma y no tb e th e mos tefficien

tcontro l for hand lay-u

p moldin g becaus e th e operato rha

s t o wor k clos e t o styrene-emialn g surfaces . I f th e emissio n rat

e o f siyrene vapor durin

g differer u phase s i s known , i

tmakes selectio n ofwhic h ventilatio n principl e t o us e t o ensure adequat e contro l muc

h simpler . I n orde rt o reduc e di e employees ' styrene exposure , so calle d low-styrene-emissio n (LSE ) resin s hav

e bee n intro duced . The reduaio n i n emissio n ha s bee n achieve d b

y adding suppressan

tadditive s to th e resin . According to gravimetric evaporation tests , th e us e o f thes e agent

s i n th e resi n decrease s styren e emissio n level s 50-9 0 percent.- ^ In thes e tests , a weighe d amoun to f catalyze d resin i s poure d Int

o a preweighe d dis c mol d an d th e los s o

f weigh ti s deteae d b y a laborator y balance during curing . Th e us e o f

LS E resins , however , ha

s no tsucceede d in reducin g th e exposur e i n th e workshop s as effectivel y a s assume d o n th e basi s o f

th e gravimetric evaporation tests . Th e overall reducdono f

th e styren e exposur e i n th e workshop s usin g LS

E resin ? ha

s bee n -so-s o percentor^'We h lgss.Q j s-? ) Therefore , th e gravimetric tes tmethod , base d o n th e determinatio n o f

siyren e evaporation unde rstatic , laborator y conditions , doe s no tftve a corre a estimat e o f th e emissio n rat

e o f styrene i n actua

l moldin g operations. - tn e ai m o i dii s t>md

y ~ tu-deiWTmin

r rhp.rmi-wte

n nttc y o f styrene monome rfro

m tw o differentpolyeste rresins during hand lay-u

p molding . Th e emissio n rate s wer e de termine d by measuring th e flow rat e an d th e concentratio

n o f styren e i n th e exhaus tduo . Th e evaporation rate s o f styren e a tdifferentphase s o f

th e moldin g operatio n ar e reported . Th

e result s ca n b e use d a s th e criteria fb rde signing ventilatio

n an d other engineerin g contro l measures. Material s an d Method s Th e emissio n rates o f

styren e monome r wer e measure d from tw o differentpolyeste r resin s b y determinin g th e flow rat e o f styren e evaporated durin g th e han d lay-u p moldin g process . Th e commerciall y available resins use d

79 0 -M?-3aXttfS-79-|"BJ*0/ « © 1» t AI H Apn. OCCUP. tNvmoN. HYB. eia) • SWEMBEI

. IM IP. 3 .W , RU

G 3 1 '9 5 11:43A

M EPf i DURHR M
TABL E I . Propertie s o f Teste d Resin s Resi n type Styw wconiem . % Viscosit y a t 2CTC . mPa s Con e an d Plat e Bfootfield . 1 0 min- ' Curin g a t 20'C . 10 0 0 resin , 1 % ME Kperoxid e Ge l time , mi n Pea k -BOtherm , * C Gravimetri c styren e evaporatio n g/m 2 Standar d 41. 3 21 8 120 0 43.0 10 7 8 0 LS

E 40. 4 20 5 148 0 41. 0 10 3 3 0

i n thi s stud y wer e preaccelerated , o f th e thixotropi c an

d onhophtali c type , an d intende d forboa tbuildin g an

d othe r simila r ope n mol d methods . Th e firstresin was a low styrene-emissio n type , wherea s th e secon d wa s a conven tiona l "standard " resin . The characteristic s o f th e resins are give n i n Tabl e I. Th e evaporatio n test s wer e carrie d ou ti n controlle d laborator y condition s b y usin g 0.16 5 m 2 laminates . Fou r o r twelv e layers o f

45 0 j*/m*

- emulsion-boun d choppe d strand ma

twer e lai d dow n a

ta resin-to-glas s ratio o f

2.3 3 usin g a meta

l rolle r t o we tou tth e glass . Thes e tw o laminat e thicknesse s wer e selecte d becaus e the y ar e widel y use d i n industry . Th e resi n wa s catalyzed wit

h 1 percento

f methyl ethy l keton e peroxide . Th e test s wer e carrie d ou ti n a n enclosur e (

V = > 0.6 0 m b y 0.4 5 m b y 0.3 0 m ) mad e o f plastic film, which wa

s ereae d insid e th e laborator y hoo d (Figur

e 1) . The test plat e wa s laminate d insid e th e plastic enclosure . I n th e test , a weighe d amoun to f resi n an d glas s libe r ma

twer e laminate d on e laye r a

ta time , an d th e laminat

e rolle d afte

r applicatio n o f

eac h layer. Th e rollin g time wa s abou t5 minute s i n th e cas e o f

th e 4-laye

r laminat e an d range d fro m 11. 5 t o 1 3 minute s i n th e cas e o f th e 12-laye

r laminate .

STYREN E CONCENTRATIO N EXHAUS T A M PLO W RAT E LABORATOR Y CUPBOAR D PLASTI C ENCLOSUR E

AI R TEMPERATUR E RELATIV E HUMIDIT Y AMVELOcrn r TEMPERATUR E INSID E LAMINAT E

ROM E 1 . Experimenta l setu p to r th e measuremen t o t styren e emissio n dur in g han d lay-u p moldin g o f reinforce d polyester . P . 3/ 5 Afte rrolling , th e laminat

e was lef tinsid e th e enclosur e unti l i twas cure d Eac

h laminat e thicknes s an

d resi n type wa s teste d twice . Th e ai r wa s exhausted fro m th e enclosur e a tth e flow rate, Q , o f

0.1 2 mVs. The tim e constan to f the enclosure , V/Q , wa s 0. 7 seconds , enablin g rapid measure men to f th e styren e emissio n fro m th e exhaus tair

. The concentratio n o

f siyren e wa

s continuousl y mea

sure d i n the exhaus tdu a durin g th e activ e lamination an d th e subsequen texother m wit h a n infrare d analyzer (Mira

n 1 A , wavelengt

h 11.05 nm , pathlengt

h 20.2 5 m, sli t1 mm) . Th e airflo w rat

e i n th e exhaustdu a (diamete r 20 0 mm ) wa s measured usin g a calibrated orific e flowmeterlocate d a ta distance o f

seve n due-diameter s from th e junctio n o f th e hoo d The pressur e dro p acros s th e orific e mete rwa s deteae d b

y a micromanomete r (Alno r 3KDS) . Th e mass flow rat e o f styren e wa s obtaine d b y multiplyin g th e con centration o f

styren e an d th e ai

rflow rat e i n th e exhaus t du a Another Mira

n 1 A was use d to dete a possibl e leakage o f styrene a

tth e fronto f

th e enclosure . N o leakage wa s observe d however . Thermocouple s wet £ use d to measure the . temperatur

e insid e th e laminat

e an d o f th e ai rabov e th e laminate . Th e accurac y o f th e styren e concentratio n measuremen

twa s estimate d t

o b e 5 percen tan

d th e accurac y o f th e ai r flo w measurementwas abou t5 percent , givin g on e overal l emissio n rat e measurementaccurac

y o f 7 percen t Ai r velocities , deteae d wit h a ho twir e anemometer , varied from 0.1 5 t o 0.2 5 m/ s abov e th e laminat

e an d rep resente d velocitie s normally found l n worksho p air. The direaio n o f

th e ai r flow wa

s paralle l t o th e tes tplate . The ai rtemperatur

e durin g di e test

s wa s 22°C , an d th e relative humidit y varied from 2 0 t o 3 0 percen t Result s The emissio n rat

e o f styrene varie d strongl y wit h tim e (Figure 2) . The emissio n rat e wa s highes tdurin g th e phas e o f rolling . Whe

n th e lamination was finishe d th e emissio n rat e decrease d rapidly i n th e cas e o f LS E resin , whereas wid i standar

d resin , th e evaporation continue d intensively . I n th e curin g phas e o f

th e LS E resin , a stron g emissio n puls e accompanie d th e heatgeneratio n insid e th e laminat e (Figure 2) . Vit h standard resin , th e change s i n th e emissio n rate afte rrollin g wer e notabl

y les s tha n wit h th e LS E resin . Th e tota l amount s o f styren e tha

tevaporate d during han d lay-u p moldin g are give n i n Table II. Th e tota l evap oratio n o f styren e wit h LS

E resi n wa s 30-6 0 percen tlowe r tha n tha i o f standar d resin . The average emissio n rates o f styrene durin g di e rollin g ranged from 5 9 t o 7 9 rcgfefai 2
. I n th e cas e o f

th e 12-layer laminate , th e emissio n rat e o f th e standar

d resi n wa s 7 9 mgferm 2 and tha i ofth e LS E resin 7 6 mgft/m

2
. Th e correspondin g value s fb rth e four-laye

r laminat e wer e 6 8 mgft/m 2 an

d 5 9 mg/s/m 2 , respeaively . Figur e 3 show s th e proportion s o f styren e evaporated a

t differentphase s o f

th e laminadon process . The result s indicat e tha tboth resi n types release d aboutth e same amoun to f styren e durin g rolling - O n th e othe rhand , the evaporation o f

styren e durin g th e tim e betwee n th e rollin g

APH. OCCUP. EHm0N.HY6.m • SEPTtMBEMS I 79 1AU G 3 1 '9 5 11:44A M EP R DURHAM P. 4

N E
! 

## P < ( B 

# I i U i * c > > 1 - m 11 0 10 0 9 0 e o 7 0 e o s o 4 0 3 0 2 0 1 0 • '

' J l

• A\j \ ¥ \ \ ' m W

^ M » W * -*•- ' __i_*i-._r x E • • / %
/ ' \ / f ^ 1 *
, ' * ' 

## B

•

. * • • y\jf —EMISSION ; STANOAA D NCSI N , y A """ - EMISSION ; LS E neei M ,**• * \ TEII*» ; StAKOAA D BMI M V^f>^«-»*Nt>MH c T6HIP ; LS E WSI N -

- •

- 11 0 10 0

• 0 e o r o 1 e o s o 4 0 3 0 2 0 1 0 0 1 0 2 0 3«

i 4 0 6 0 B 0 7 0 8 0 9 0 10 0
*__t_ m i IMA * 'Roiu«a * 

## s e 

# I
u . o w e c 3

Ul

o IU

RGURE 2

. Th e emissio n rat e B : th e 12-laye rlaminate

. 1 CUMNC J • TIM E (min )
o ( styren e an d m e temperature Insid e A : th e 4-laye rlaminat e P

. 4/ 5

an d

TAB U II . Th e Overa U Styren e Ha s Durin g Han d Lay-U p o t Tes t laminat e
Tes t No . 1 2 3 4 S 6 7 8 Resi n Typ e ST O ST D LS E LS E ST O ST D IS E LS E Umtnat e Thicknes s 4-laye r 4-ltye r 4-ftye r 4-laye r 12-taye r 12-tay w 12-laye r 12-laye r Tota l Styren e

Evaporatio n (fitaf l 11 6 12 4 S O 5 5 18 2 1S 3 12 4 11 1 Styren e Loa a

% o f Resi n Volatil e Conten t 6. 9 5. 8 2 3 1 3 1 4 2 8 2 4 l\ ST O - sandM t (_S

E • * kj*«»rer__-tr_sslo* v

-**• » an d curin g phases wit

h th e standar

d resi n was fou

rtim e greatertha

n tha twit h th e LS E resin . Discussio n Th e evaporation o f

styren e i s greates tdurin g the rollln process , a s was show n b y Pritchar d an d Swap_llai.

<6 > E i pedall y wit

h th e LS E resin , abou t30-5 0 percen to f t h tota l evaporatio

n occurred i n th e sho n rolling phase. Hen o th e durado n o f

th e rollin g phas e dominate s th e evapo n do n o f sryten e whe n LS

E resi n i s used . I n th e cas e < standar d resin , ther e wa s als o considerabl e evapotado afte r th e active lamination . Changes i n th e rollin g time d i nothave a s stron g a

n effe a o n th e tou l styrene emtssi c

APPLOCCUP. O/VMOW

. HYG. 6U)

. SEPTEMBE R 1 9P. 5 AU G 3 1 '9 5 11=44A M EP A DURHA M

{____ ] CURIN G PHAS E ES S PHAS E BETWEE N ROLUN G AN D CURIN G ROLLIN G PHAS E
1S0

e x 

# I 

# I 5 U l IOO

6 0

ST D LS E ST O LS E 12-LAYE R LAMINAT E 4-LAYE R LAMINAT E FIGUR E 3 . Th e overal l siyren e evaporatio n divide d int o subgroup

s accordin g to laminatio n period . ST O * standar

d resin; LSE - low-styrene-emisslo n resin .

a s wit h th e LS E resin . Durin g th e rolling , di e emissio n rat e o f styren e was 4-1 4 percen tlowe r wid i LS E resin tha

n wid i standar

d resi a Th e average emissio n tare s observe d i n dii s smd y ar e i n agreemen twii h earlie r results. (6 > Variation s i n styren e evaporatio n betwee n replicate d tests , •whic h wer e o n th e orde r o f

6-1 6 percent, wer e als o i n accord with dat

a give n by Pritchar

d an d SwapiUaL

( * > Compared t o di e standar d resin , di e LS

E resi n ha

s a P . 5/ 5 lowe revaporation rat

e during di e perio d becwee n di e rollin g an d curing . Thi s 6 a explain s th e smalle r tota l mas s o f styrene evaporated from th e LS E resi a Th e determi nation o f styrene evaporatio

n wit h th e gravimetri c testpro cedur e doe s no tInclude th e rollin g phase . Th e tes tresult s obtained wit

h th e gravimetric tes tprocedure , therefore , underestimat

e di e emissio n o f

styren e i n th e actua

l mold in g operadon . Becaus e di e rat

e o f styren e vapo r generatio n i s highes t during di e rollin g phase , i ti s o f crucia l importanc e t o keep dii s perio d a s shortas possible . Th e rollin g tim e can b e minimize d b y usin g resin s an d mat s wit h goo d wetou t properties . The us e o f

LS E resin s notabl y reduce s di e tota l evaporatio n o f styren e compare d wit h standar d resi a "Whe

n LS E resin s are used , di e engineerin g contro l measures shoul d focu s o n th e rollin g an d curin g phases . Reference s 1 . KalUokodd

, P. : Kolsdnen . T. ; JUsketiinen , M J Preventio n o f Styren e H-oards—Hygienic Approaches , ti tIndustria l Hazards o f

Mastl a an

d Synthetic Elastomers , pp . 279-286 . J . J__tvisak> , P . PflOU , an d H. vunlo , B & Ala n R . Us s lot . Ne w Yo * (1984) . 2 . fan inkn-d--, P. ; SMmAnen , A ; halo . L*

. Kokoc L R : Eapotut e t o Styren

e Ca n B e Controlled - Am

. Ind. Hyg. Asso c J

. 49- 1 (1968) . 3 . Sch\imicher,iU^Breys*^PA;C__riyCftW._U ^ i n di e Fiberglass Fabricatio n Industr y i n Washingto n Sou . An . la d Hyg . Asso c J . 42:14 3 (1981) . 4 Todd , TO.; Shulman, SA. . Contro l o f Scyren e Vapori n a Larg

e Fiberglas s Boa tM-mufanurtp

g Open-don . Am. In d Hyg . Asso c J . 45-81 7 (1»4) . 5 . *fl"-al__-^L_;S*cdcwvS_tLow-Scyiene-E-iut' ^ bi n th e Wortplxe . Mo d Plas t62:7 8 (1985) . 6. Pritchard. G. ; Swapilla

L GJ. : Styrene Los

s Dunn g th e Fabricatio

n o f Glass Reinforced Polyease r Products . SAMP

S J . 14:1 9 (1978) . 7 . Duffy , MJ_ > Reducin g Stytene Emissio n from Unsaturated Polyester. Plas . Eng . 35-33 0979 }
Rmfci d M« h mfe

wMsiM i MO/90 : ffiHslon 2/4/91 ; anp M 2/2S9 1

APPLOCCUP. ENVtltON. HYG. Nt) • SEPTEMBE

R 1" ! 79 3