Radiation‐induced polymerization of glass‐forming systems. I. Effect of temperature on the initial polymerization rate

Abstract

Abstract Radiation‐induced polymerization of hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) was investigated. HEMA and GMA formed a stable supercooled or glassy phase by themselves at low temperatures. It was found that the initial polymerization rate was proportional to ca.0.5 power of the dose rate in the region of relatively high temperatures and the dose rate exponent changed sharply to 1.0 at a temperature T r , at which the viscosity of monomeric systems reached ca. 10 3 cP as the temperature decreased. Moreover, a maximum in the polymerization rate–temperature curve occurred at T v . It was deduced that the polymerization mechanism changed from the stationary to the nonstationary at T v . The temperature at which a minimum of the polymerization rate occurred could be calculated kinetically considering the viscosity dependency of termination rate, and it agreed well with that obtained experimentally. It was deduced that occurrence of the minimum polymerization rate above T v was attributable mainly to the decrease in termination rate due to diffusion control.