Mutual sensibilization in epoxyacrylate interpenetrating polymer networks
Using the method of IR spectroscopy, the kinetic features of the course of photoinitiated cationic and free radical polymerization in simultaneous epoxyacrylate interpenetrating polymer networks were investigated. The degree and rate of conversion of epoxy groups in the epoxy component (aliphatic diepoxide UP-650D, aliphatic-alicyclic triepoxide UP-650T, and diane epoxides ED-20 and Epicot 828), and the opening of double bonds in acrylate component (triethylene glycol dimethacrylate) were determined. The sensitizing effect of the acrylate component on the degree of conversion of epoxy groups in IPNs with aliphatic diepoxide or aliphatic-alicyclic triepoxide with an epoxy/acrylate ratio of 50/50 wt. % was revealed. For diane epoxies, the opposite regularity of conversion of epoxy groups in the composition of epoxy-acrylate IPNs is observed: in comparison with initial polymer networks, the degree of conversion of epoxy groups was significantly reduced. In the first case of low-viscosity aliphatic and cycloaliphatic epoxides such a sensitization is occurred due to the fact that the simultaneous polymerization of acrylate via a free radical mechanism promotes the decomposition of the photoinitiator and the formation of more macrocations quantity. In second case of more viscous diane epoxy resins, the spatial restriction imposed by the rapidly formed acrylate networks is predominate. That is why the conversion of epoxy groups is reduced and this effect is neutralized.