ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Tetrafluoroethylene (A) and 1,2,3,4,5-pentafluorostyrene (B) were irradiated at 15°C at autogenous pressure by use of 30-92 mole-% A and at 5000 atm by use of 42-99.9 mole-% A. The high-pressure results indicate that the reactivity ratio rA for monomer addition to A-ended radicals is 0.005; the other reactivity ratio rB appears to vary from 15 to 60 generally increasing with the A content of the charge. At autogenous pressure rA is small, but a precise determination is not possible because of the very low polymerization rate when the A content of the charge is high. However, if rA is less than 0.01, then values of rB vary from 15 to 50, again generally increasing with the A content of the charge. Mixtures of A and B exhibit positive deviations from Raoult's Law. Activity coefficients were measured at autogeneous pressure and used in an attempt to correct rB for the nonideality of solution. The range of rB was reduced only slightly to 8-27, and charges with high A contents now generally gave low values of rB; consequently, this approach was not regarded as a success. Another attempt was made to account for the apparent variation in rB by ascribing influence to the penultimate units of the radicals. Improved agreement between theoretical and observed compositions resulted, but significant discrepancies remained unexplained. Rate data agreed well with those calculated from a theoretical copolymer rate equation using values of rA and rB of 0.0045 and 40, respectively. The equation predicts an almost proportional decrease in rate with increasing proportions of A in the charge from 0 to 99 mole-% A.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1975.170130718
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