Document YDbVp2rjGqXxQyJv6dpdb9E10

Section I - Nylon-Teflon 7 - 2- August 31, 1981 ^ezz4rH55 C. FC-143 in Teflon Products - S. S. Shelburne Objective: Determine levels of FC-143 in the Teflon process and the condi tions for removal of and identification of byproducts of thermal treatment. Status: Heating of FC-143 ammonium salt/Triton X-100 mixtures at 175C and analyzing off gases by IK. show that decarboxylation, with CO2 and a perfluoromonohydride as byproducts, occurs in FC-143 thermal treatment. Although the FC soncentration on I yarn is too low to use IR for positive identification of perfluoro byproducts, heating the yarn to 200 or 250C and measuring the decrease in off gas absorbance by IR does confirm previous work that thermal treatment is an effective means of removing the FC. There is no evidence of evaporation, but the IR scan does show the presence of unidentified compounds. Mass spec will be necessary to identify these. A study of the decarboxylation reaction shows two possible products, (1) the perfluoromonohydride or (2) the perfluoroolefin (Ref. 1, 2). t// , ^ CF3 CCF2>6 c - 0 ~ M C F 3 (cf2)5 cf2h..+ co2 M+ = NH4+ , Na+ C F 3 (CF2), CF - CF2 + CC>2 The monohydride is observed in the IR as a peak at 3010 cm- ^ (C-H Stretch, Figure I, SSS). There is no evidence for the perfluoroolefine which would absorb at ^ 1790 cm (CF CF2 ). The spectra shows evidence of other compounds binds the monohydride, probably from the Triton. If it is necessary to identify these, mass spec analysis must be run in Wilmington. Samples were run by heating them from 125-175C in a Teflon column in a GC. The GC allowed the use of controlled N 2 purge and temperature. The evolved gases are carried to a 10 cm IS cell through tubing. All samples are heated at 125C for 30 minutes to remove water. The Nicolet TTIR is used in a repetitive scan mode, usually with a 5 minute scan time. Yarn samples were run initially, but the low FC concentration caused a change to FC/Triton liquid mixture. To emphasize the IR peaks, the solutions were run at 5:1 Trton/FC ratio rather than the actual 50:1 ratio. Uve NHl salt scans show C02 and CF2 absorbance peaks as early as 150C, but the hydride peak does not appear until after 5-6 minutes at 175C. This is due to ita- low-mass and probably low absorptivity. This time cannot be compared to earlier kinetics work because of low purge flows and thus, the time necessary to displace the volume of the tubing and cell (v 11 minutes). Ref. 1 - LaZerte, JD; JACS:75, 4525 (1953) Ref. 2 - PCSD 58-131 - R.G. Meschke 00008^ SPR001317 EID715195 Section I - Nylon-Teflon - 3- August 31, 1981 The low purge is necessary to prevent excessive dilution in the IR cell. However, Teflon "I" yarn samples, which contain the sodium salt, heated at 200C showed a decrease in the CO2 and CF2 peaks after 25 minutes, indicating that the decarboxylation was complete. At 250C, the same peaks start to decrease after ^ 8 minutes. (Table I-SSS) These do con firm that the temperatures in the previous work were correct. Work is continuing to quantity the degree of decarboxylation with the sodium salt and to trap the off gases for better identification. 000085 SPR001318 EID715196 , - S e c tign_I_- MyIon-Teflon_____________- 4 - August 31. 1981 7=75"'7r5T36- ------- 00006 EID715197 , --Section I - Nylon-Teflon* - 5- August 31, 1981 TABLE I-SSS FC-143 OFF GAS IR ANALYSIS N2 Flow 20 ml/mia. Time for Volume Displacement - 11 Minutes Sample I. NH4FC143/Triton 2g/10 gr. Temp. Increase 8/min. Temp. 150 175 tl II tl tl If II. Teflon I Yarn 3.5 gr. Heat Time 125-200C 6.5 min. 200 IT 11 If rt Tl IV [II. Teflon I Y a m 3.65 gr. Heat Time 125-250C 10.5 min. 250 If It 11 fl TT Time Min. 0 1 5 8 13 25 0 2 10 16 21 25 30 0 8 16 21 26 31 C-H-3010 cm-1 - 1 2 5 10 Non-detect r? rt tl u Non-detect 11 tl tl n rt C02-2340 cm-1 3 7 10 26 36 50 82 2 3 11 19 18 18 12 14 18 16 16 12 11 CF2-1250 cm-1 4.5 11 15 29 38 44 99 10 12 19 21 21 23 18 31 16 8 5 4 - 000067 SPR001320 EID715198