Abstract
The bulk copolymerization of styrene and acrylonitrile with 2, 2''-azobisisobutyronitrile as the initiator, was carried out under ultrasonic irradiation. The effects of ultrasonic waves on the copolymerization rate and the average molecular weight of polymer were studied. It was found that the kinetic scheme of copolymerization was not affected by ultrasound, but that the kintic parameters were affected by ultrasonic waves except for the rate constant of acrylonitrile homopolymerization, δ''B, and reactivity ratios, rA and rB. The rate constant of styrene homopolymerization, δ''A, andØ value increased with ultrasonic irradiation, although initiator efficiency decreased slightly with ultrasonic irradiation. It is suggested from these results that ultrasonic waves increased the recombination of two free radicals.
