Radiation‐induced graft polymerization: The trommsdorff effect of methanol

Abstract The radiation‐induced graft polymerization of styrene to low density polyethylene was investigated. It was found that dilution of the styrene monomer with methanol accelerates the rate of graft polymerization with a maximum effect occurring at approximately 70 vol.‐% methanol. Both the accelerated and unaccelerated graft polymerizations yield volumetric or homogeneous graft copolymers. Experiments in which n ‐octane was substituted for methanol as the diluent showed that the accelerative effects of methanol are best explained by the incursion of a Trommsdorff‐type effect. The k p 2 /k t values for the grafting reaction in the various styrene‐methanol solutions were calculated. It was found that the k p 2 /k t term is larger in grafting than in homopolymerization by a factor of 10 3 , and that it increases as the methanol concentration of the monomer solution increases.