Free‐radical grafting of monomers to polydienes. I. Effect of reaction conditions on grafting of styrene to polybutadiene

Abstract

Abstract The radical‐induced grafting of styrene onto polybutadiene (PBD) in benzene solution at 60°C has been studied. Provided the PBD concentration is kept below about 1.0 monomermole/l. the polymerization of styrene shows normal kinetic behavior. The proportion of polystyrene incorporated as graft is independent of the initiator (benzoyl peroxide) concentration but increases as the ratio of PBD to styrene in the reaction medium increases. Azobisisobutyronitrile produces no graft copolymer in this system. It appears that the reaction leading to graft formation is direct attack of initiator radicals on the rubber, probably by a hydrogen‐abstraction reaction.