Radiation-induced polymerization of tetrafluoroethylene and 1,2,3,4,5-pentafluorostyrene at high pressure

Autor: Robert E. Lowry, Daniel W. Brown
Rok vydání: 1975
Předmět:
Zdroj: Journal of Polymer Science: Polymer Chemistry Edition. 13:1677-1689
ISSN: 1542-9369
0360-6376
DOI: 10.1002/pol.1975.170130718
Popis: Tetrafluoroethylene (A) and 1,2,3,4,5-pentafluorostyrene (B) were irradiated at 15/sup 0/C at autogenous pressure by use of 30 to 92 mole percent A and at 5000 atm by use of 42 to 99.9 mole percent A. The high-pressure results indicate that the reactivity ratio r/sub A/ for monomer addition to A-ended radicals is 0.005; the other reactivity ratio r/sub B/ appears to vary from 15 to 60 generally increasing with the A content of the charge. At autogenous pressure r/sub A/ 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 r/sub A/ is less than 0.01, then values of r/sub B/ 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 r/sub B/ for the nonideality of solution. The range of r/sub B/ was reduced only slightly to 8 to 27, and charges with high A contents now generally gave low values of r/sub B/; consequently, this approach was not regarded as amore » success. Another attempt was made to account for the apparent variation in r/sub B/ 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 r/sub A/ and r/sub B/ 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 percent A.« less
Databáze: OpenAIRE
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