FRONT PHOTOPOLYMERIZATION AT CONSTANT EXT INCTION AND LIMITED MASS-TRANSFER

Radical photopolymerization in media with constant extinction and weak or zero mass transfer was studied. The conditions at which photopolym erization proceeds as a front reaction were analyzed. It was shown tha t front photopolymerization occurs when, in addition to a special form of the reaction kinetic law, the dimension of the sample in the direc tion of propagation of the irradiating light is sufficiently large. Wh en the latter condition is not satisfied, polymerization proceeds not as a wave process, but rather as a spatially ordered quasi front proce ss. Experimental investigation of photopolymerization of acrylamide-ba sed mixtures showed that this reaction indeed occurs as a quasi-front process. A quantitative criterion was proposed, which determines the o nset of the regime of front polymerization.