Document n0pX5e1zJr85nvg0B8dVKLV6

ETHYL CORPORATION RESEARCH AND DEVELOPMENT DEPARTMENT BATON ROUGE LOUISIANA THE 1VTFFUSIVTTY OF VCM TN 8237 BOTTLE COMPOUND A PRELIMINARY REPORT December 19, 1975 G. A. Daniels G. C. Gackc ri THE DirruSTVTTY OF VCM TN 8237 BOTTLE CO>!POUNT) Abstract Diffusivity values for VCM in 8237 PVC bottle compound have been measured for cubes with initial VCM concentrations 0.04 mg/kg to 37 mg/kg when surrounded by air, water, and 50 percent aqueous ethanol at 75*F and 120*F. The cubes of PVC and the surrounding medium were sealed in 156 ml serum bottles and .the quantity of VCM diffused out of the cubes was determined by measuring the concentration of VCM in the head space as a function of time. The results of the experiment indicate: 1. The quantity of VCM diffused from the PVC cubes is proportional to the initial VCM concentration. The diffusion process is linear. 2. The room temperature diffusivity of VCM in 8237 PVC bottle compound is greater than in PVC pipe compound by a factor of 2 to 3. 3. The surrounding medium is important. The diffusivity of VCM in 8237 PVC compound surrounded by water is 1.5-2 times the diffusivity of VCM in 8237 PVC compound surrounded by air while if the surrounding medium is 50 percent ethanol the diffusivity value is 5-7 times the value in the air experiments. SPl-02933 ^Introduction The purpose of the experimental work presented in this report was to determine the effect of the concentration of vinyl chloride monomer (VCM) in the PVC on the diffusion rate and the diffusivity of VCM in 8237 PVC bottle compound and to determine the effect on diffusion rates of air, water, and a 50 percent aqueous ethanol solution as the medium surrounding the PVC. Earlier studies made of the diffusion of VCM from 8237 compound PVC bottles into 50 percent ethanol solutions were made at VCM levels of 100-400 ppm v;hile 8237 PVC bottle compound manufactured at present contains less than 1 ppm VCM. It is desirable, therefore, co determine if the diffusivity is the same at the 1 ppm level as at the higher levels. The question of the effect of the surrounding medium arises from a comparison of the room temperature (75F) diffusivity of VCM deter mined for PVC pipe compound (6.6 10"1J cmi/sec) surrounded by air or water as compared to the diffusivity determined for 8237 compound bottles filled with 50 percent ethanol (1.04 10~11 cm2/sec). The composition of 8237 bottle compound is not the same as for PVC pipe compound (the major difference is the impact modifier in the bottle compound) so that the difference between pipe and bottle compound could be due to composition or to the solvent effect of the surrounding medium or to both reasons. Experimental Design Cubes (about 0.12") of 8237 PVC bottle compound were added to a 156 ml serum bottle and 50 ml of the surrounding solvent (if any) was added. For runs at room temperature and the runs at 120F using water as the surrounding medium the charge of PVC cubes was 50 ml (65 g) while the charge was 100 g for the 120F run using air as the surrounding medium. Four samples of PVC cubes were used 0.04, 0.43, 5.5, and 37 mg VCM/Kg PVC. Duplicate or triplicate serum bottles were prepared for each condition and time. The time schedule was 1, 3, and 6 weeks for the 120F experiments with air, and 1, 3, 6, and 12 weeks for .the 120F experiments using water and air. For all the room temperature experiments, the time schedule is 3, 9, 18, and 36 weeks. The concentration of VCM in the head space of the serum bottles is determined by a gas chromatograph with a flame ionization detector. The total quantity of VCM in the head space and the surrounding medium (if present) is calculated using the volume of the head space, the volume of the surrounding medium and experimental values of the distribution coefficient between the solvent and air. These values were 0.973 for concentration of VCM in air compared to water (g/ml in gas)/(g/ml in water) end 0.208 for the concentration of VCM in air compared to 50 percent ethanol). SPI-02934 F.xperlmentnl ftpsul ts The experimental program for 8237 PVC bottle compound using air as the surrounding medium is complete. The 1208F run using water as the surrounding medium as well as all the room temperature runs are incomplete. The experimental results are given in Tables 1-5. The values given in Tables 1-5 represent average values for the replicated runs, except in a few cases where leaks appeared to occur, these values were not included in the averages. Analysis of Experimental Data A diffusion model has been used to analyze the experimental data and to estimate approximate diffusivity value of VCM in 8237 PVC bottle compound when surrounded by different materials. The following assumptions have been made in analyzing the data. 1. The fluid phases surrounding the PVC cubes is perfectly mixed. 2. The concentration of VCM at the surface of cubes is in equili brium with the concentration of VCM in the fluid phases. This equili brium is described by a Henry's law constant. 3. The rate controlling step is the diffusion of VCM in' the solid phase. The diffusion coefficient is assumed to be independent of concentration. 4. The concentration profile in the solid at the start of the experiment is given by the solution of the diffusion equation with initial constant composition and zero on the boundary for the manufacturing and storage period before the experiment was started. 5. The cubes can be treated as spheres. Mathematical solutions are available1 for the case of diffusion from a sphere into a finite mixed solvent for the case of constant initial composition and have been derived for the case of the initial concentration being the solution of the diffusion equation with zero on the boundary**. The corresponding equations for a cube arc not available and appear to represent a formid able problem in solution. Diffusion coefficients derived from the equations for spheres are only approximations but comparison between the diffusion coefficients for various cases is valid. A study of the experimental data in Tables 1-5 shows that the amount of VCM that has diffused into the headspace is proportional to the initial concentration of VCM in the PVC cubes. For the case of Sample 1 (0.04 mg VCM/Kg PVC) in air at 120*F the headspace analyses are of questionable validity as Large interferring peaks vjere present ,Crflnk "Mathematics of Diffusion," page 84-98,. Oxford, 1956. *Thcse equations are presented in the Appendix. SPl-02935 1 in the chromatographic charts. Except for these data, all concentra tions dependent data for each case have been pooled. This linear behavior of the quantity of VCM diffused with initial VCM concentration is strong evidence that both the Henry's law constant and the diffusion coefficient in independent of concentration in the region studied. The approximate values of the diffusion coefficient calculated from this study are given in Table 6. j| It is apparent from the data given in Table 6 that both the composition of the PVC compound and the surrounding medium can make significant changes in the diffusivity of VCM. As would be expected, temperature is a significant variable. Water did not appear to have a' significant effect on the diffusivity of VCM in pipe compound but for 8237 PVC bottle compound the diffusivity of VCM for water as the sur rounding medium is 1.5-2.0 times larger than for air while the diffu sivity of VCM for 50% ethanol as the surrounding medium 5-7 times larger than for air. The diffusivity of VCM in 8237 bottle compound is 2-3 times the diffusivity in PVC pipe compound. SPl-02936 APPENDIX SPI-02937 TABLE 1 8237 PVC Bottle Compound at 120F Air is the Surrounding Medium I Sample Initial VCM mg/Kg TPM VCM in Headspace V/V jig VCM diffused out of cubes PPM VCM in Headspace V/V jig VCM diffused out of cubes TPM VCM in Headspace V/V jig VCM diffused out of cubes 1 0.04 * ~1 0.25 m li8* 0.44 2 0.43 . 5.7 1.42 3 Weeks 9.9 2.48 1 6* 6 Weeks 11.1 0.40 2.78 4 5.5 77. 19.4 118. 29.7 134.5 33.8 7 37. 514. 135.8 715. 179.3 827. 207.4 interfering peaks in chromatographic chart makes these data very uncertain. SPI-02938 TABLE 2 8237 PVC Bottle Compound at 120F Water Is the Surrounding Medium Sample I2 Initial VCM mg/Kg * <* 0.04 0.43 1 Week PPM VCM in Headspace V/V ug VCM diffused out of cubes 0.46 0.125 4.8 1.32 3 Weeks PPM VCM in Headspace V/V jig VCM diffused out of cubes 0.84 0.23' 8.0 2.20 6 Weeks PPM VCM in Headspace V/V jig VCM diffused out of cubes 1.25 0.33 9.9 2.62 12 Weeks PPM VCM in Headspace V/V jig VCM diffused out of cubes 4 5.5 69.5 19.1 79.3 28.2 111. 29.4 '7 i 37 468. 128.5 730. 202. 764.' 203. SPI-02939 TAm,K 3 8237 PVC Bottle Compound at Room Temperature Air Is the Surrounding Medium Sample Initial VCM mg/Kg 1 0.04 2 0.43 . '4 5.5 PPM VCM in Headspace V/V pg VCM diffused out of cubes PPM VCM in Headspace V/V jig VCM diffused out of cubes PPM VCM in Headspace V/V jig VCM diffused out of cubes PPM VCM in Headspace V/V jig VCM diffused out of cubes ' 3 Weeks 0.125 0.98 0.035 *;.265 9 Weeks 0.19 1.95 0.052 0.529 18 Weeks 36 Weeks 13.0 3.52 24.4 6.59 7 37 77.4 21.0 137.5 37.2 SPI-02940 TABLE 4 8237 PVC Bottle Compound at Room Temperature Water is the Surrounding Medium________ Sample 12 Initial VCM mg/Kg 0.04 0.43 PPM VCM in Headspace V/V pg VCM diffused out of cubes 0.11 0.03 3 Weeks '' 1.3 0.355 PPM VCM in Headspace V/V pg VCM diffused out of cubes 0.20 0.053 9 Weeks 2.6 0.71 PPM VCM in Headspace V/V jig VCM diffused out of cubes JULy.eeJaS. PPM VCM in Headspace V/V pg VCM diffused out of cubes 36 Weeks 4 5.5 18.0 4.92 33.5 8.94 7 37. 120.5 33.2 239. 63.8 SPI-02941 TABLE 0 - Dtffustvltv of VCM In PVC Conriounris Compound Surrounding Temperature 8237 Bottle 8237 Bottle 8237 Bottle 8237 Bottle 8237 Bottle 8237 Bottle* 8237 Bottle* PVC Pipe . PVC Pipe Air Water Air Water 50% Eth'anol Air - 50% Ethanol Air - 50% Ethanol Air Water 120 120 75 75. 75 120 75 75 75 Diffusivity pm*/sec 1.5 <> 10- n 3.3 ' 10" 11 1.4 <' 10-" 2.1 10 12 8.0 1 10'12 8.3 ' 10-11 1.04 10"11 6.6 10'13 6.6 10"13 Bottle extraction experiments. SPI-02942 iXi /'LL'j.d / j'j 1^-, .> I j-OT- and r k,> ' * ` ` ZEf7jJ~j*J *rt ac > o * <vV>i d)y -}-M<z. Sc /-f-i o*+ 4$ 'f'hc. *7) i j-J-*-iS/r*< 444 A t+i t'J\ <*/< :-}*>i/ jT/r/4`*-/ /o .*7 / 0 ."I-/r-v*//\> St r-J JZ+j-o (5tT O r~ i/A 'TZtu-n/* *- 7 "*,b kV _3>s - )/ ^S + A a ^ Br"' r $r/ dSd** r^sL^r"^ C*} fL >i 6 ( f< - $ < r- = d) Q. - dlXAd fdi,\. ~ (jlft-J r~- * <Fy **' ( * .t'r*' ij /.* o^*. fitA-d-tri*] J*s11 !?*.} C. ,\d~ > ^ f * *** <&*;- - 3 gft_3 Oft y ir r r, 5i'^<L2r) ^V - j0 --n 2-r 'Jy- *3 c/u.4? - ___4A___ v_--^- \ -_ ^ 0*^ ___ a~*- 'TTi`Clt'"7) L_ - r-t** , y- oo a* r ^-/ eUfhT) ^^ * &" 0,0 r~ - j_/LJi_^ *, -lw' - 1Vj c<v7 '4WJ||^) 'y ' '* ' '*'727 iv{ r - A. u b fiA ^ ^ ^ S) aY * * oc*. _L Y nr'Oti) -- __ ^ ^ /rA-i* _ r\ " + SPI-02943 3 < y ____*_A _ ) A` .;;; ', *777-7* (1 -- /.<'' "'"-Yl A* m * | mzo-ids 'A -? !('<> -f tf rVfz/r^ <'/ / * / ^ ^ |\yi-j.5Nt r-> *ry wyj* j***/? tjj >p? v~ p " | i*+1p ** *' ?.^A rr ~ V-*f t P^' IfsP* "**?/- ^f t- o jy} ) I./* y - *?-* j- v i-*c^ - >; - ^I = >4 * >t * - y7 = *7 .2 >* -hS "'if 2 { `J5-f4-<?o^ -- *Z- ~T7- ? -.-u--,^) `Hi Q^t-p) t-n-f^[ `-5? ,*. s> < , ~ 9~ (*78 ?& , cx? * oO / =V U '?$' '?J--^--* u " 'V' P /-j- r>--t S> i^ro-p VT OO ya / v\/.|3 /. 2 *7 Predicted VCM Concentration In The Contents of PVC Bottles Manufactured From PVC Compound Containing 1 mg/kg VCM (1 ppm) j j( | , .I The three attached charts show the VCM content of 50 per cent ethanol (Figure 1) and water (Figure 2 and Figure 3) calculated for e level of VCM in the PVC of 1 mg/kg assuming no VCM is lost during blowing. The diffusivity of VCM in 3237 bottle compound used for Pigures 1 and 2 is 1.04 10"1* cmJ/sec which was derived fretn our studies of 50 per cent ethanol in 2 ounce bottles presented in our January 17, 1975, repott. Figure 3 shows the same calculation using a value of 2.1 10'11 craJ/sec for the diffusivity of VCM in PVC exposed to water taken from our preliminary report of December 19, 1975, describing our studies of the diffusion of VCM from cubes into air, vater and 50 per cent ethanol. The lower value of the diffusivity changes the time scale of the diffusion of VCM into water but does not change the maximum concentration in the water. CAD/bwb SPI-02945 V) in t O P VJ 0- Q. U4 o v> _ r* Hi ~~ m. k N h ( /- T" * :::. Hi ~! :): Ht! : A-:-. -: Hi: ? rr-r . . 'r-f 03/9iv; Wc/J ` S1N31N0D 311108 Nl W3l\ SPI-02946 F/& U .R E 2 VCf'A CONTEXT OF W ATER S T 0 R F D IN VYC BOTTLES (W/9W Wdd ' SLH3J.HQ0 dllLOFl Nl 'vLOA SPI-02947 SPI-02948 Oari)W)Wdd'9-LM3JLNOD 1U10Q i\'l "WOA ' II I C o/ o<;;: aoir a.\ out o.s /.o ;:.o r i lT//..-U* Ai n-R I !/./n x ynAVS AT 7/7 F .5/0 /o .o Part 2 - Additional Comments on Analytical Procedures (including the relevant analytical procedures as Attachment 1). The analytical method used in this work is given in Attachment 1 to this addendum. The method used is a manual headspace analysis. SPI-02949 A TiftQifiii&tVT" / l A GAS CHROMATOGRAPHIC METHOD FOR THE MEASURE;^?? OF PARTS PER 3ILLI0K VIK'fL C~ IRIDE MCHCMER INj WATER AI'ID '50$ ETHAHOL BY HEADSPACE ANALYSIS ! ' I. Scope This method is designed to determine parts per billion quantities of vinyl chloride monomer in water and 50ethanol by analysis of the gas in the headspace above the liquid by flame ionization gas chromatography. II. Outline of Method . The liquid sample is sealed in a serum type bottle and stored at ambient temperature. A. one milliliter sample of the gas in the vapor space from the bottle is injected into the gas chromatograph. From the concentration found in the headspace and the par tition coefficient, the concentration of VC1 in.the liquid is determined. III. Apparatus '" A. Gas Chromatograph - A Bendix 2200 gas chromatograph or the equivalent equipped with a flame ionization detector. B. Gas Chromatographic Column - A 1/8" x-25' stainless steel column pacxeu with 5C/S SZ-52 on 80/lC0 mesh. Gas j Chrom Q conditioned for 16 hours at 2C0C. C. Syringe - A 2.0 ml., gas tight. Series A-2 Pressure-Lok syringe from Precision Sampling Corp., Baton Rouge, Louisiana 70S15. D. Data Collection System - A Hewlett-Packard 3320 recording integrator or-computer (IBM/7). E. Serum Pottles - 125 ml nominal capacity, complete with serum stoppers (flat rubber with Teflon face) and aluminum caps. . Rc-agents . A. Vinyl Chloride Monomer in Nitrogen Car Standards: -1 SPI-02950 LS6Z0-|dS * paz/Ci-cui; sx csxduiBS jo sajjos v aiupq ipca qno popaj-co aq pxnoqs 'jopqx'jqxxPO sxmi paupucqs up (uidd) XOA jo uopqraquaouoo = o >lTBad xoa Jo * V (iwid/sqxun uoj\:) joqoxij uoxq \Mqxxi.'D = jo :o.ioq Y B dO :skoxtoj s-e sxs^X'BUtj qouo joj joqo'ej uopqejqxx^? ? sq'exnox'so s-aaj'e SuppuodsaJ -joo jpaqq pub spJBpuBqs aqq jo ucpqBJquaouoo aqq tuoJ, y.Bad XDA sqq Jo BSJBaqq suxuuaqap pub (aqBOTTdTJq up pasAx^'j-s aq ppnous pjBpuBqs qoBa) qcBJSoqBuiojqo sb9 aqq oqup pjBpuBqs sb3 qoaa jo sqor.bpx'e iai o'T qosfui `V uopqBJqpxaj `iA (0o0-s) quapquiy - aJnqBJacuisj, usao ' * 0oOOC - aJnqBJacaaj, joqosqaa OpOST - -ciujsi qj*d uopqoafui ;g suoxqxpuoo mnu;pqdo joj t^hubui quaurcuqsup oq Jajag - aq^H f-oid Jpy * suoxqppuoo anutxqdo joj .xboubui quaiunjqsup oq jsjelh'- eqBg A'.oxi usecjpah '*?) uopqBzpuop auiBXi - uoqaaqaa *g uxui/oo o q* umpxaH - sbq Japu^ao *v suopqppuoo opqcBJi>oqBUiOJiJ0 sbd ''A 'X290Z xmapspnoi 'a2non uoqag 'xt? xog 'OV 'uopuBJodJop _ . X^u.qi usojj axq'EXTBA'e `Aqpjnd qSpH - spxaomo X-^upA 'S '5I80Z auBpsxnox' 'a9noa uoqcg f sav epoq'a- gzztj 'sasBQ x^pjqsnpui oojpy JO quauiqjBdaa saopAJas x'sopqZx^uy sbo u;ojj axQ^TTBAB (a/a) udd oQ Pub uidd c>z - spjBpuaqs sbo uopqBJqpxB'o 'Z 6SOZO' T 'N 'AuJBay. '"av uostjjbh OOXI f'POJ<j qoai, OW; jo uopstatq opjxquapos D/I uiojj exqBXPBAB (a/a) uidd ox P.0'8 wdd x " sbo uopqBJqpiBO T^oxupw *1 I ____ __ x (p.quoo) squoiiBaa '*-Xi VII. -D---e--t-e---r-m----in--a--ti--o-n----o---f----P---a---r--t-i-t-i-o---n-----C----o--e---f-f-i-c--i-e---n--t- r A. Transfer a known volume (100 ml) of liquid (water or 50# ethanol) to a 125 ail (155 ml actual volume) serum bottle. Seal the bottle with a serum stopper and alu minum cap. By means of a calibrated 10 ul gas tight syringe, inject 2.0 ul of pure vinyl chloride into the' liquid in tne sealed bottle. Prepare additional sam.pies containing 5.0 ul and 10.0 ul of pure vinyl chloride per 100 ml of liquid. Shake the samples for 10 minutes and allow to stand for 15-50 minutes for vapor/liquid equilibrium to be established. B. By means of a 2 ml gas tight syringe, withdraw approx imately 1.4 ml of vapor space (headspace) from the sam ple bottle. Adjust the volume to 1.6 ml and inject into the gas chromatograph. Measure the area of the VC1 peak. Repeat this procedure for the other samples. C. Calculate the partition coefficient (vapor/liquid) as follows: _____c' (HS) * 'Ilia.) _______ P.C (VVC1 x 2.55) - jb'(HS) * V(HS)) where: P.C. = partition coefficient (vapor/liquid) c`(HS) * concentration (ug/l) of VC1 in headspace C1(HS) = C(HS) * . C(HS) = concentration (ppm v/v) of VC1 in headspace 62.5 = mol. wt. of VC1 . 24.45 = molar volume 25C and 760 mm Hg v(uq) =* volume (liters) of liquid phase V(VC1) = volume (ul) of VC1 injected 2.55- = vapor density (ug/u1 of VC1 at 25eC and 750 mm Hg V(S) ** volume (liters) of headspace SP1-02952 The partition coefficient for water is approximately one and the partition coefficient for 50# ethanol is approximately 0.2 based on experimental data'obtained In the Ethyl R&D laboratories. VIII. Procedure . A.' Carefully transfer 100 ml of the liquid to be analysed (water or 50# .ethanol) to a 125 ml (15o ml actual) serum bottle. Insert a serum stopper and seal with an. aluminum cap. Shake the bottle for io minutes and allow to stand for 15 minutes to establish vapor/liquid equilibrium. B. .Insert the needle of a 2 ml gas tight syringe into the vapor space of the bottle and withdraw about 1.4 ml of-vapor (headspace) into the syringe. Adjust.the sam- ' pie volume to 1.0 ml and inject into the gas chromato graph. Measure the area of the vinyl chloride peak. C. For 50# ethanol samples, heat the column oven to 100C for about five minutes after the VC1 peak has eluted to elute ethanol from the column. Reestablish the column at ambient (25-30C) before analyzing any additional samples. i IX. Calculations A. Calculate the original concentration of VC1 in the liquid . as follows: C'.(H8) * v(llq) . C'(HS-? x V(Hq) . ----------- L&------------------------------------ ------- v(iiq) where: C(liqj = concentration (ug/l) of VC1 in the liquid Cr (HS) = concentration (pg/l) of VC1 in headspace (HS) = c(ns) x :(IIS) = concentration (ppm v/v) found of VC1 in heart:; pace. 62.5 = mol. wt. of VC1 24.45." molar volume at 25C and 760 mm Ifg V(liq)= volume (liters) of liquid P.C. = partition coefficient (Section VII) ^(HS) = volume (liters) of headspace * SPI-02953 X. Precision and Accuracy i A. The precision of the method has been found to be 10-15# relative for concentrations belov/ ICO ug/l (ppb). The accuracy is dependent on the accuracy of the determination of the partition coefficient which is 10-15# for water. B. The limit of detection for water samples is estimated to be < 1 ug/l and the limit of detection for 50# ethanol samples is estimated to be about 5 Ug/l. /idt 10-50-75 SPI-02954 ADDENDUM D This attachment is relevant to the Ethyl Corporation submission "Vinyl Chloride Migration from PVC Dottles to Vegetable Oils and Food Simulating Solvents" dated September 17, 1976: Part 1 - The original submission reproduced in its entirety Part 2 - Additional information requested and submitted October 20, 1976 reproduced in its entirety (includes chromatograms) Part 3 - Additional Comments on Methodology Part 4 - Additional Comments on Analytical Procedures with Analytical Procedures provided as Attach ments No. 1 and No. 2 SPI-02955