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Reactions of radicals with polymers—III. Abstraction reactions of methyl and tert. butyl radicals with poly(p-tert. butyl styrene)

✍ Scribed by N.A. Weir; M. Rujimethabhas

Publisher
Elsevier Science
Year
1985
Tongue
English
Weight
506 KB
Volume
21
Category
Article
ISSN
0014-3057

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✦ Synopsis

The kinetics of H abstraction by methyl and tert.butyl radicals from poly(p-tert.butyl styrene) (PTL3) films (5 × 10 3 mm thick) have been investigated at 298 K, both radicals being produced from the polymer by its exposure to short-wave u.v. radiation (2 = 254 nm) at pressures < 10 -4 Pa. Differential equations describing simultaneous diffusion and reaction of each of the radicals have been developed, and their solutions (for both steady and non-steady state conditions) used along with the experimentally determined abstraction products (CH 4 and C4HI0) to evaluate rate constants for abstraction, which occurs predominantly at the ~-carbon atoms in the polymer, the values of the rate constants for the two radicals were unexpectedly different (by at least a factor of 103) and explanations are advanced. Steady and non-steady state solutions rapidly converge. Experimental and theoretical product evolution (based on the solutions of the equations) were compared; deviations between the two sets of data, appearing after about 2 hr photolysis, are discussed.

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