Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/41137

Title

Evaluation of the kinetic-parameters for styrene polymerization and their chain-length dependence by kinetic simulation and pulsed-laser photolysis

Author(s)

Deady, M.;  Mau, Albert W. H.;  Moad, Graeme;  Spurling, Thomas H.

Abstract

Pulsed laser photolysis (PLP) has been employed to determine propagation rate constants k(p) for styrene polymerization in benzene over a wider temperature range (20 - 80-degrees-C) than previously covered. It is proposed that a small chain length dependence of k(p) (overall) may, in part, be a consequence of a marked chain length dependence of k(p) for the first few propagation steps [i. e. k(p)(1) > k(p)(2) > k(p)(3) greater-than-or-equal-to k(p) (greater-than-or-equal-to 4)]. The propagation rate constant for styrene polymerization is given by the expressions: In k(p) = 16,0(9) - 289(50)/(RT) (overall) or ln k(p) = 16,4(7) - 300(84)/(RT) (chain length greater-than-or-equal-to 4). Kinetic simulation has been applied both as an aid in data analysis and to demonstrate the reliability of the PLP technique for evaluation of propagation rate constants (k(p)) in radical polymerization. This has been achieved by examining the sensitivity of the molecular weight distribution of polymers formed in PLP experiments to the values of the kinetic parameters associated with polymerization and their chain length dependence. The termination rate constants (k(t) = k(c) + k(d)) and the ratio of combination to disproportionation (k(c):k(d)) markedly affect the molecular weight distribution of polymer formed in PLP experiments. The prospects for evaluating the values of k(t), its chain length dependence and k(c): k(d) by direct analysis of the molecular weight distribution are discussed in the light of these results.

Publication type

Journal article

Source

Die Makromolekulare Chemie-Macromolecular Chemistry and Physics, Vol. 194, no. 6 (1993), pp. 1691-1705

Publication year

1993

Keyword(s)

Chemistry;  PLP;  Polymers;  Pulsed laser photolysis;  Synthetic products

Publisher

Hüthig & Wepf Verla

ISSN

0025-116X

Peer reviewed