Relaxation studies of the seeded emulsion polymerization of styrene initiated by γ-radiolysis

Abstract

Results are reported for the relaxation kinetics of the emulsion polymerization of styrene in seeded systems initiated by γ-radiolysis. The decay in the rate of polymerization after removal from the radiation field was followed dilatometrically. The data were interpreted using an extended Smith—Ewart theory. This confirmed values for the rate coefficients for both the first-order loss of free radicals from the particles (k) and the entry of thermally generated free radicals into the particles (p_ρ) obtained in a separate chemically initiated study. Temperature-dependent studies showed that these two rate coefficients, for particles of radius 48 ± 2 nm, could be expressed as log(k/s^–1)=(3.8 ± 0.5)–(42–10kJ mol^–1/2.303 RT), and log(p_ρ/S^–1)=(10.4 ± 1.0)–(87 ± 10 kJ mol^–1/2.303 RT).