Post-Irradiation Study of Highly Converted Styrene-Polystyrene Systems

Abstract

<p> The post-irradiation annealing of highly converted styrene-polystyrene systems was explored. Experimental conditions necessary for the entrapment of high concentrations of free radicals in such systems were investigated. They were found to bear a relation to the glass transition temperature of the system.</p> <p> The concentration of free radicals formed by subjecting the polymer-monomer systems to Gamma rays, at room temperature, was measured, and the subsequent GM and GP values were calculated. The structure of the formed radical was found to be in agreement with that suggested by previous investigators. The free radicals decay was examined at varied temperatures above and below Tgs, and was found to follow a second order mechanism. The activation energy of decay was found to increase by raising the temperature above Tgs.</p> <p> When irradiation was executed at temperatures below Tgs, post-irradiation annealing led to high rates of polymerization when carried out at temperatures above Tgs. </p> <p> The number average molecular weight was practically unchanged during the polymerization of the last few percent monomer.</p>