A STUDY OF EPOXY RESIN-ACRYLATED POLYURETHANE SEMIINTERPENETRATING POLYMER NETWORKS

Epoxy resin-acrylated polyurethane semi-interpenetrating polymer netwo rks (semi-IPNs) were synthesized containing various ratios of the digl ycidyl ether of bisphenol-A (DGEBA)-based epoxy resin and an acrylated aliphatic urethane oligomer. The synthesis was carried out in the pre sence of a mixture of triarylsulfonium hexafluoroantimonate salts as a dual photoinitiator that initiates both the cationic polymerization o f the epoxy resin and the free-radical polymerization of the acrylated urethane oligomer simultaneously, upon irradiation with ultraviolet l ight. The simultaneous photopolymerization, followed by isothermal dif ferential scanning calorimetry measurements, gave rise to simultaneous semi-interpenetrating polymer networks (semi-SINs). During polymeriza tion, partial inhibition of the cationic polymerization was noticed. T his was investigated by determination of the gel content and the infra red spectroscopy of the soluble fraction, after extraction of the synt hesized polymer films in a Soxhlet apparatus, and by determination of the network density of investigated systems with thermal mechanical an alysis. The compatibility of the components in the semi-IPNs was inves tigated by dynamic mechanical thermal analysis. It was found that glas s transition temperatures are shifted inwardly, which indicated that t he epoxy resin-acrylated polyurethane semi-IPNs were compatible. (C) 1 998 John Wiley & Sons, Inc.