Color and radical formation in irradiated polyvinyl chloride

Abstract

Abstract When polyvinyl chloride is irradiated with high energy radiation a visible color change varying through green‐yellow to deep red‐black is produced, depending upon the dose and temperature. Spectrophotometric and electron spin resonance techniques were used to investigate the formation of colored material by 2‐m.e.v. electron irradiation of unplasticized polyvinyl chloride moldings. The observed chemistry of the colored material is in agreement with the postulations of earlier workers that colored polyene structures are formed. Three radiation‐produced free radicals decaying at room temperature with half‐lives of 4.5, 63, and 1630 hr. were observed. The color in the 550 mμ region was found to be inversely proportional to the concentration of the long‐lived radical. The presence of absorption maxima in the 350–500 mμ region was observed in irradiated moldings and in tetrahydrofuran solutions of irradiated moldings.