SYNTHESIS OF POLYMER MATERIALS BY LOW-ENERGY ELECTRON-BEAM .2. EFFECTS OF IRRADIATION DOSE ON EB-CURED POLYURETHANE ACRYLATE GEL FILMS

The structure and properties of the gel films obtained from the electron beam (EB) solid-state polymerization of urethane-acrylate prepolymer were investigated as functions of EB irradiation dose. The film of a prepolymer which was synthesized by the reaction of poly(butylene adipate)diol, 4,4 prime -diphenylmethane diisocyanate, and 2-hydroxyethyl acrylate, contained the crystalline phase arising from poly(butylene adipate). Spherulitic texture was observed on the gel film surfaces by scanning electron microscopy. Spherulitic size decreased drastically from 2. 5 to 5 Mrad and diminished gradually from 5 to 20 Mrad. Such features of the gel films as functions of EB dose resulted in maximum values at 2. 5 Mrad on stress at yield.