Influence of electron beam irradiation on hydrolysis of polyethylene terephthalate

The purpose of this paper is to study the influence of a small chemical change produced by electron beam irradiation with moderate radiation doses on the hydrolysis of polyethylene terephthalate (I) films which were crystallized by biaxial stretching. The density and melting point slightly decrease with radiation doses, but the glass transition temperature is constant. The hydrolysis of irradiated and unirradiated I films under saturated water vapour pressure at 1800C has been investigated by X-ray and thermal analyses. An irradiated I film becomes extremely hydrolyzable compared with an unirradiated one. It was found that crystalline region in an irradiated I film is considerably destroyed by hydrolysis, while crystalline region in an unirradiated I film is stable against hydrolysis. It is considered that the defects in both amorphous and crystalline regions formed by chain scission and recombination reactions in electron beam irradiation processes remarkably affect the hydrolysis of I films. (auth.)