Document 5DvbDJxoYX0Q99Ee2NVez6bOD

APPENDIX 2 AR226-2379 AHALTOICAL TECHNIQUE USED TO DETERMINE C-8 CONCENTRATION IM AQUEOUS SOLUTION The basis for the analytical technique used to determine the C-8 concentration Itt an aqueous solution was Polymer Products Departnent method Code No. T 212.2000 (revised 8-7-81). The referenced method is for the determination of equivalent C-8 dispersing agent in PEP aqueous dispersion. By using the method with and without the addition of an aliquot of an unknown C-8 sample, is was possible, by difference, to determine the concentration of the unknown C-8 sample. The following is a description of how the method was adapted for use. A 'large' source of aqueous FEP dispersion vas obtained for use in this analysis. The dispersion was stored in a plastic container until needed. when used, the dispersion vas gently mixed and then filtered through 'cheese cloth' to remove large pieces of coagulated dispersion. The filtered dispersion vas used for all samples for the day's analyses. For purposes of this technique, 10 +/- 0.01 grains of FEP dispersion were used, made up to 100 ml with demineralized water using a graduated cylinder. The equivalent C-8 concentration in the PEP dispersion vas determined using Method T 212.2000. This concentration vas considered the 'blank'. In actual usage, only the volume of CTMAB (cetyltrimethylammonium bromide, 1.0 gin/liter) required to coagulate the FBP dispersion vas recorded. A second measurement was made, similar to the first, but vhere a measured volume of the unknown C-8 solution was added to the FEP dispersion. In the second measurement, additional CTHAB would be required to complex with the additional C-B present before the PEP dispersion would coagulate. By difference (the amount of CTHAB required for the unknown sample relative to the 'blank'), the quantity of the unknown additional C-8 could be determined and, hence, its concentration. The theory upon which the method is based is that each mole of CTHAB will complex with a mole of equivalent C-8 and that the complex will have no dispersant properites. When sufficient C-8 has been removed from the solution, the FEP dispersion will be destabilized and coagulate. The supernate will be clear after the dispersion 'breaks'. This method requires the laboratorian to determine the point when enough CTMAB has been added to the dispersion sample so that the liquid above the coagulated dispersion is clear. This point was not always easy to determine and at times varied between laboratorians. However, within a single day using the same experienced laboratorian, the results appeared to be internally consistent. RJZ031108 EID179722 APPENDIX 2 2 o 5 Below is the equation used in this technique: Cx (Vx - Vb) -------------- x Vex 1000 x 431 ---------- 364.48 here Cx Concentration (in Bigm/l) of the unknown C-8 solution. Vx Volume (in als) of CIMAB solution required to coagulate the PEP dispersion and the aliquot of unknown C-B solution. Vb Volume (in nis) of CTH&B solution required to coagulate the FEP dispersion without any added C-8 solution, Vex 1000 Volume (in mis) of the aliquot of unknown C-8 solution. Concentration (in Bga/1) of CTMAB standard solution. 431 Molecular weight of C-B (as ammonium perfluorooctanoate). 364.48 Formula weight of CTMAB. Typical results are shown below: (22.6 - 8.9) 431 Cx = ------------------ x 1000 x -------- = 4,050 TOgm/l 4.0 364.48 RJZ031I09 EID179723 APPENDIX 2 3 of 5 I. E- d.u Font de Hemours & Co. (Inc.) Polymer Products Department Code ffo. 1 212.2000 Revised: 8-7-81 Page 1 of 3 TEFIjDH* FEP FLUQBOCAKBOH HESPT. AQUHTOS DISPEBSIOH . Equivalent C-8 Dispersing Agent I. II. III. IV. V. VI. VII. VIII. IX. Scope ana Applications This method, la applicable to determining the equivalent C-8 dispersing agent in PEP dispersion. Principle Percent C-8 is determined by titrating FEP dispersion with a solution of cetyltriiaethylainnoniuiB bromide. Interferencea 3enaitivitr Precisi-on, and Accuracy The precision (aigma) of this test based, on five runs made on one sample is 0.0005 with an X of 0.1254X ,C-8. Apparatus Reagents 1. CetyltriBietcylaannioniuB broaiide (CTMAB), 1 g/liter Operating Conditions (RC 190.127) Safety and Health Precautions As dispersion or coagulation effluent can contain C-8, contact with dispersion should 'be avoided by -wearing the proper gloves. The current allowa.'ble exposure limit for C~8 is below 1 ppl and. C-8 is suspected of being teratogenlc. Procedure 1. Weigh 25 (* 0.01) g FEP dispersion into a oOO-Bl bearer. 2. Add 200 ml (grad. cyl) deain water to the dispersion. 3. Stir the beaker using a magnetic stirrer until the dispersion and water are mixed (about 30 seconds}. l. Pill a buret with 1 g/liter CTMAB solution. Record the reading. * Reg. U.S. Pat. & TB. Off. RJZ031110 EID179724 APPENDIX 2 4 of 5 Page 2 of 3 it 5. Using the buret, add CTMAB solution to the dispersion slowly, with constant magnetic stirring. As CTMAB ia added, polynier vill 'begin to coagulate. When appears that most of the- polymer has coagulated., stop adding CTMAB and then stop agitation a few seconds later. 6. AUcw the bulk of the polymer to settle out and observe the supernatant liquid. If it ia cloudy, resume agitation and add 0.2 to 0.5 ml of CTMAB. 7. Stop agitation and allow to settle. 8. Repeat steps 6 and 7 until the supernatant liquid is perfectly clear. A elaar supernatant liquid is the end point of the titration. 9. Becord the buret reading. 10. Find specific gravity of the dispersion and percent solids, using -Method. I 202.80U. 11. Calculate % C-8 and g C-8/g rSP. X. Calculations 1. Calculation of % C-8 mL CTMAB = (step 9 - step If-) % C-8 inl. CTMAB x 0.1184 wt of dispersion, g --- --,---oi^, = [0.027 5 (Normality of CTMAB)] x r'tBlCM.y.)] x ------------- 1000 (ing/g) 100(%) XI. XII. 2. Calculation of s C-8/g TTS f. TSS = % solids (step 10) % C-8 froitt step 1. Calculation ^-pp = gpgp Report two significant figures, i.e., .091!?- Calibration Notes RJZ031111 EID179725 APPENDIX 2 5 of 5 Code Bo. T 212.2000 Revised; 8-1-81 Page 3 of 3 XIII. References 1. Couture. M. J., Washington Works Technical laboratory notebook Bo. 1026, pp 68-89 2. Plastics Department Laboratory Test Method T 202.8(AO 3. Original Method, Washington Works Technical Laboratory, 3-U-T1 4. First Revision, Washington Works Technical lAboratory, 2-16-T6 Be-riaed to reflect the use of C-8 instead of C-9 in TEP polymerization. Origin: Washington Works Technical Laboratory, Is-t Circulation 5-15-81 Prepared by: C. W. Jones Approved by: D. L. Kerbow Approved by tabora-tory Methods Conanittee, 8-7-81 WW-2989 RJZ031112 EID179726