Document mBZybEGoRZ0ex8o7001Q7VkDQ

AR226-2533 FLUOROPOLYMERS 81-4 PAGE 10 3. Measurement of Residual C-8 Fluorosurfactant Levels on Various Products - C. S. COPE - Following the report from 3M Company that "Fluorad" FC-143 (C-8 APFC) surfactant had been found teratogenic in tests with laboratory animals, we received several company requests for analytical determination of residual C-8 concentrations in various TEFLOK-based products. Included were two types of TEFLOH-eoated felt produced by F&F Department's Falrfleld, Conn., plant, a sample of TEFLOW-coated glass cloth manufactured by J. P. Stevens Co. (sub mitted by S,. J,. Ca^aaaugh of Research), and two samples of TE-9724-J TEFLOM PFA baked powder (prior to extrusion) manufactured at Shimizu (analysis requested by P. Thistleton of the Technical Department). As a reference point concerning residual levels of C-8 APFC on our it TEFLON products, may be noted that the Customary Advisory Letter issued to our customers on 4-1-81 by the Sales Division stated: "With the exception of aqueous dispersions, there is no significant residual FC-143 in any of the fluoropolymer resins which we sell." This statement is not inconsistent with the fact that very low levels, of the order of 1-5 ppm, of residual C-8 APFC have been detected (using a method which is not specific for C-8) in the past on TEFLOM fine powders and granular resins, the main products we sell in dry, bulk form In the unextruded condition. (Extruded resins should contain even lower levels of residual C-8.) Analyses of all these samples were performed by boiling the samples in a dilute aqueous solution of phosphoric acid In the presence of a nonvolatile, nonlontc detergent ("Triton" X-100). Perfluorocapryllc acid is sufficiently volatile at lOO'C that it steam-distills off under these conditions. The C-8 in the distillate Is then analyzed by the chloroform/Azure A(a-blue dye) colorlmetric method, sensitive to about 2-3 micrograns. The method Is nonspecific for C-8, and other ionic surfactants can, in principle. Interfere. In no case among the recent samples was a residual C-8 concentration above the range typically found on TEFLOH fine powder detected. For the F&F felt samples, values of 3.5 ppm (unbleached felt XT-7700) and 0.7 ppm (bleached felt IT-7800) were obtained. For the J. P. Stevens Co. fabric, we found 0.35 ppm (equivalent to 3.95 ppm based on TEFLON solids present). For the TE-9724-J samples; concentrations of 2.8 and 1.0 ppm were found. Results have been trans mitted in writing to those who requested the analyses. The most recent analyses of residual C-8 APFC on fine powder were obtained In March on a set of three samples of TEFLOH 64 submitted by E. H. Stueber of the .-Technical Department. Two of these samples were from lots which had performed poorly in wire-coating at Thennatics Corporation, while the third was a control which performed normally. Technical *s request for C-8 analyses was prompted by a desire to test, in the absence of any clear-cut distinctions in the normal characterization data, whether possible differences in residual C-8 level might account for the differences in fabrication behavior. The two unsatisfactory lots, with residual C-8 levels of 4.2 and 2.5 ppm, were found to w ^ be somewhat above the control (1.5 ppm) in this respect, but by no means enough g so to Be considered unusual. Furthermore, tests done years ago showed that 3^ ii EID089900 v EID089900 -.'"' f 1 ? .. ^ FLTOROPOLTMERS 81-4 PAGE 12 4. C-8 Fluorosurfactant Analyses on Samples Received from the gEP Area - C. S. COPE Requests were re'eelwed from Technical Department personnel in the PEP Area for C--8 fluorosurfactant analyses on several polymer and water samples. The polymer samples were taken from the Torus Disc Dryer and asso ciated equipment at a time when dryer performance-was being questioned. The water samples were taken as part of the program to establish a material balance on C-8 distribution in the FEP Area. In all cases, the C--8 was recovered from the samples by distillation in the presence of dilute aqueous phosphoric acid. Indications are that this treatment is relatively effective in separating out any "in situ" dispersing agent from the C--8 APFC. With the polymer samples, a nonvolatile, nonlonic detergent ("Triton" X-100) was added to promote wetting. Analyses of the distillates from the polymer samples happened to be carried out by titration with cetyltrimethylammonium bromide, whereas with the distillates from the aqueous samples (run at a later date), the chloroform/Azure A method was employed. Results of the analyses are presented in Table II-CSC. The measured C-8 concentrations on the polymer samples provided it few surprises, having been established earlier that the Torus-Disc Dryer serves to remove most of the C-8 from the (wet) feed entering from the V-Disc Press. Since the C-8 removed from the polymer discharges through the dryer vent line leading to the water scrubber, a polymer plug in this line would be expected to contain more C-8 than the dry polymer exit the dryer. Dry polymer removed from the rotor of the dryer would be expected to have a C--8 content comparable with that of the dryer product. Two earlier measurements of C-8 level on the dryer product gave values of "6 and 34 ppm, bracketing the value of 17 now obtained on the polymer scraped from the dryer rotor. The concentration of 1950 ppm (0.195%) found on the sample taken from the lid of the screw conveyor now located between the discharge of the V-Disc Press and the entrance to the Torus-Disc Dryer was much higher than at first expected, based on previous measurements on V-Disc Press product samples, which had equivalent C-8 concentrations of 0.042Z and 0.066?. The differences are even greater when differences in water content are taken into account (the dispersing agent is expected to be predominantly adsorbed on the polymer, rather than in the aqueous phase). The recent sample contained 70% water (total basis), vs. 24.5Z and 14.8Z, respectively. In the earlier Samples, making the relative C-8 concentrations, expressed on a water-free basis, .different by about an order of magnitude. We postulate that this difference is attributable to back-leakage of C-8-contalning vapor from the dryer during the period when dryer performance was unsatisfactory. The C--8 would be expected to have condensed out on cool surfaces, such as the screw conveyor lid, the top of which was exposed to the ambient atmosphere. - <3\ EID089902 ^ EID089902 TLUOROPOLXMERS 81-4 PAGE 13 TABLE II-CSC C-8 FLUOROSuKPACIAHT ANALYSES ON SAMPLES FROM THE FEP ABEA (Submitted by A. R. Behnke and J. R. Eyitts, Technical Department) Sample Identification____ Date Submitted Measured Concentration of Equivalent C-8 APFC, ppm (Based on Initial Weight) Polymer Samples (Analyzed by CIMAB Titratlon) Polymer scraped from rotor of Torus-Disc Dryer 3/30/81 Sample of.plug found in vent line of Torus-Disc Dryer. 3/30/81 Dust sample'from lid of Screw Conveyor feeding Torus-Disc Dryer <70Z TS.yO, total basis) 4/2/81 17 170 1950 Water Samples (Analyzed by CHCl-/Azure A Method) TEFLON 100 Cbagulator Effluent (Batch 21-4111) 4/27/81 260 TEFLON 100 PK (First) Rinse Water (Batch 21-4111) 4/27/81 15 (0.12Z polymer solids present) EBD089903 EID089903