KINETIC-STUDY ON THERMAL POLYMERIZATION AND CROSS-LINKING OF PRE-IRRADIATED 1,4-BUTANEDIOL DIACRYLATE

The thermal polymerization and cross-linking of 1,4-butanediol diacryl ate taking place after irradiation was followed kinetically in the tem perature range from 60 to 140-degrees-C. Low conversions were reached by polychromatic pre-irradiation in the absence of any photoinitiating species. The disappearance of double bonds follows first-order kineti cs, up to degree of conversion 0,4 < x < 0,5, and then proceeds up to high x values, according to a multiple relaxation phenomenon, characte rized by the same mean relaxation lifetime as first-order kinetics. Ac tivation parameters also were calculated. The present results on the d ecay of double bonds are discussed in the framework of the classical p olymerization mechanism and in connection with previous kinetical data on the decay of radicals trapped in the same pre-irradiated monomer, obtained by electron paramagnetic resonance (EPR) measurements. Propag ation and termination processes depend in the same way on the mobility of the vitrified polymerized network, both being diffusion-controlled .