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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 TEFL0N-based products. Included were two types of TEFLOKO-coated felt produced by "F&F Department's Fairfield, Conn., plant, a sample of TEFLON-coated glass cloth manufactured by J. P. Stevens Co. (sub mitted by . J. Cavanaugh of Research), and two samples of TE-9724-J TEFLON 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 TEFLON products, it 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 TEFLON 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 11 these samples were performed by boiling the samples in a dilute aqueous solution of phosphoric acid in the presence of a nonvolatile, nonionic detergent (''Triton" X-100). Peifluorocaprylic acid is sufficiently volatile at 100C that it steam-distills off under these conditions. The C-8 in the distillate is them analyzed by the chloroform/Azure A(a-blue dye) colori metric method, sensitive to about 2-3 micrograms. 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 TEFLON fine powder detected. For the F&F felt samples, values of 3.5 ppm (unbleached felt XT--7700) and 0.7 ppm (bleached felt XT-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 TEFLON 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 Thermatics 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 lot3 , with residual C--8 levels of 4.2 and 2.5 ppm, were found to be somewhat above the control (1.5 ppm) in this respect, but by no means enough so to Be considered unusual. Furthermore, tests done years ago showed that EID089900 EID089900 RJZ017635 fi V FUJOROPOLTMERS 81-4 PAGE 12 4. C-8 Fluorosurfactant Analyses on Samples Received from the PEP Area -- C. S. COPE Requests were received from Technical Department personnel in the FEP Area for C-- 8 fluorosurfactant analyses on several polymer and prater 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, nonionic 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-CSG. The measured C-8 concentrations on the polymer samples provided few surprises, it 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 ((K 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 0.042% 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. 24.5% and 14.8%, 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-- containing 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. EID089902 RJZQ17637 EID089902 FLUOROPOLYMERS 81-4 PAGE 13 TABLE II-CSC C-8 FLUOROSURFACTANT ANALYSES ON SAMPLES FROM THE FEP AREA (Submitted by A. R. Behnfce and J. R. Byitts, Technical Department) Sample Identification______ ' ' Date Submitted Measured Concentration of Equivalent C-8 APFC, ppm (Based on Initial Weight) Polymer Samples (Analyzed by CTMAB Titration) 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 U d of Screw Conveyor feeding Torus--Disc Dryer (70% H^O, total basis) 4/2/81 17 170 1950 Water Samples (Analyzed by CHCl^/Azure A Method) TEFLON 100 Coagulator Effluent (Batch 21-4111) 4/27/81 260 TEFLON 100 P K (First) Rinse Water (Batch 21-4111) 4/27/81 15 (0.12% polymer solids present) RJZ017638 EED089903 EID089903