Document b5z3k7z1nrwzOEoOLzJBE9axZ

I. ' - -V 2-47 K EV . 12-75 '<flUPQ3> - E5USSCI392 ( E. I.du P ont d e N em ours S C om pany . INCORPORATED P. O . B o x 1217 ' Parkersburs, W . Va. asioi PLASTIC PRODUCTS AND RESINS DEPARTMENT TO: J. P. YUK * . TEXTILE FIBERS DEPARTMENT SPRUANCE PLANT FROM: S. COPE PP&R DEPARTMENT f WASHINGTON LABORATORY AR226-3332 CC: E- D. Charapney, D13188 H. B. Voigt, Wilm A. A, Wright, T.F. Dept, Wilm M.-A. Forte, T.F. Dept, Spruance P. Thistleton, WW R. E. Putnam, WL R. G. Brown, WL S. V. Gangal, WL File: 8-5 September 25, 1979 CONCENTRATION LEVEL OF C-- 8 FLUOROSUEFACTANT f -- > IN M W 1 H ,nT::-3311 DISPERSION_________ INTRODUCTION fhB , ,, , W pk by telephone about two weeks ago concerning flUiSUrfaCtank Present in TE-3311 dispersion finite n l fro" our DeP^tment to yours for use in makingP hiS i f i S L ? 1 ^ scose.Process. At about the same time, I fcrso D i o a r S S i in jscusslons With A. A. Wright and M. A. Forte of your cuLiS!fis 38 "y understa"ai'>9 fr" " ese dis- ,,TM Analyses at Spruance of the measurable C-8 levels in r by axtraction followed by esterification and pres4nt^ lyS1S' haVe ShOWn ^ Ut 200 ppm U0-300 ppm range) to be TF v n i level of 0-8 used in the recipe for preparing would iead us to expect about 1200 ppm to be present, it has been concluded that the unaccounted-for portion of the C-8 is i ? ^ i er ibiycheld <"traPPed") Within the PTFE polymer itself, a n ! TM ? 3 Spruance to locate the "missing" C-8 elsewhere in the P lnU process or on the final product have been unsuccessful. SETTER THINGS FOR BETTER l iv in g . . . THROUGH CHEMISTRY Company Sanitized. Does not contain TSCA CBI J. P. YUK 2 September 25, 1979 These findings were not in accord with our general ex- tdaotaew5e2reeWa^viai2lSab?le, ialongC't^heisneP?liinEes^ Pf^ors iToEn-3s3,11 ailnt hpLagrthicnuolasrpecific Accordingly I set about determining the level of G^8 in J l - s S i thecas?? 7 techniques we have applied and found Reliable iA DISCUSSION The TE-33J s a m p ^ ^ i s ^ L in the following analvses was from a recent lot/ Analytical Procedures i- , None of the methods of C-8 assay available to us can be ! S i e! df eCtV "Tritonn " stabilized PTFE dispersions. It is f separate the C-8, for which purpose the technique to thf d ? ; i L ^ 0ng' acid (phosphoric acid) and water dispersion and distilling over the volatile C-8 acid (with water) was employed. A detailed description of this procedure is appended .The distillate fractions, containing successively lower f C"8 Untl1 essentially no further carry-over of methods:takin^ place' were analyzed by a variety of complementary NaOH titration Chloroform/methylene blue analysis Cety 1trimethy1ammonium bromide titration. NaOH Titration r nninf Tftration with NaOH (0.1 N) to a phenolphthalein pink Too results, when expressed as equivalent C-8 APFC 431)> are known to be hi9h ^ this method, pre sumably because of the presence of small amounts of other volatile acids carried over in the distillation. 6 Chloroform/Methylene Blue Analysis _ _ The chloroform/methylene blue analysis, regarded as the P^ ? ^ ed meiho\ of assay .in this case, is based'on forSKion S a a d ^ h o rToPle^ b6tW^ n vT cation of methylene blue hydrochloride S L 9. 8 anion- The blue-colored complex is then partitioned between fixed amounts of water and chloroform. The greater the C ~? PreSen,*' ^ more intense the blue coloration in the .J?easurement of the absorbance maximum at about 633 nm in the visible region by spectrophotometer serves as a triS assay, the relationship between absorbance and con- being established by measurement of prepared standard tht TS-f-kv0TnC "8 APPC cncentration. It has-been demonstrated bhat uT ?n XrlOO and citric acid (used at low levels in TE-3311 for chelation of any iron adventitiously present) do not interfere a f lySiS 5 dlstillafce samples by this method. A description of the chloroform/methylene blue method is appended. . __ ' .'J` Company Sanitized. Does no! contain TSCA CBI J. P. YUK 3 September 25, 1979 ^ (Incidentally, as you are no doubt aware, chloroform is now designated as a Suspect Carcinogen, and we would therefore prefer to avoid its use. However, a brief study of methylene chloride and "Freon" 113 as possible substitutes indicated that neither was suitable.) . ' Cetyltrimethylammonium Bromide Titration . ,, titration analysis using cetyltrimethylammonium bromide (CTMAB) solution (0.100% w/v) is based on the finding in this Department that the cation of CTMAB forms a neutral 1:1 molar complej^withthe C-8 anion.' This complex is not surface-active. funCei i ^ ^ ^ 3 raw dlsPersin may be used as an "indicator" for the titration; when the equivalence point is needed, the C-8 is no longer effective as a surface-active agent to keep the polymer particles dispersed, and they settle o u ^ a s a flocculent gel, leaving S f L / 2 UOUS phase flear- Actually, r a w f e H n F E P dispersion (HFP/TFE copolymer)_is preferred as indicator, since it contains less C-8 to begin with and also happens to give a perfectly clear aqueous supernate when the equivalence point is reached. _ The CTMAB method, like the chloroform/methylene blue - method, is relatively specific for C-8, though "Triton" X-100, if present, would certainly be expected to interfere. A disadvantage of the CTMAB method, insofar as your possible use of it would be concerned, is thatraw FEP dispersion has a short shelf-life and is difficult to ship without coagulation occurring. A description of the CTMAB method is appended. ^ Analytical Results A_summary of our analytical results on the TE-3311 sample tested is given in Table I. Expressed as equivalent C-8 APFC. the results obtained are: Method Used NaOH Titration CHCl3/Me Blue CTMAB Titration ppm C-8 (based on total dispersion) 1950 1140 960 _ Recognizing that the NaOH titration results were expected to be high, the agreement .among the different results is considered good. The indicated concentration of C-8 is at the level expected from our previous general experience, and several-fold higher than that obtained by extraction/GC analysis. We conclude that the G-8 present can be recovered and accounted for, and that little or no C-8 is located within the PTFE particles themselves, which, inci-. ; dentally, are known to be solid and very highly crystalline. We do know that there is an equilibrium between C-8 adsorbed on the surface of the particles and C-8 dissolved in the aoueous phase., At room temperature, the majority of the C-8 is adsorbed. Company Sanitized. Does not contain TSCA CBI I J. P. YUK 4 September 25, 1979 Note the high sensitivity of the CHClo/methylene blue method, which permits reliable determination of C-8 in amounts as low as 10 micrograms. For this reason, dilution of distillate samples (typically by 20-fold) was required prior to C-8 assay by this method. . - _ One of the main attractions of the analytical procedures just described is that they should be applicable as well to deter^ination of residual C-8 in the PTFE fiber products you produce at, One point we should like to emphasize with respect.to the C-8 analysis is that, although we have now apparently succeeded in accounting for the C-8 expected to be present, the result does not directly answer the question as to how accessible this C-8 is in terms of contact by personnel, e.g., by skin contact, or by in halation ^of vapors evolved on heating during fabrication operations. Information on this subject could come only through more extensive ' testing of a more direct nature. Program I hope in the near future to "close the balance" on C-8 in the production of TE-3311 dispersion by measuring, using the same methods given here, the C-8 concentration in the supernatant layer which is produced (and discarded) during the thermal concen tration step in which raw dispersion (45% solids known C-8 content) is treated with "Triton" X-100 and raised to the 60% solids content, of TE-3311. When these results are in hand/ X shall let you know. CSCope/ldl ' Attachments: 1 Table - 3 Analytical Methods (Spruance copies only). Company Sanitized. Does not contain TSCA CBI I