Interpenetrating polymer networks of epoxy resin and urethane acrylate resin: 2. Morphology and mechanical property

A new kind of simultaneous interpenetrating polymer networks (SINs) composed of epoxy resin (epoxy) and urethane acrylate resin (UAR) having various amounts of hard segment and prepared with poly(oxypropylene) polyol (PPO) having different molecular weights was synthesized and the relationship between the morphologies and mechanical properties of these SINs was investigated in detail. It was found that the different morphologies of these SINs were related to various structures of UAR network. The morphology of such SINs not only depends on the compatibility between the poly(methyl methyacrylate) segments existing in UAR network and epoxy network, but is related to the microphase separation of UAR network as well. The experimental data showed that the epoxy network could be toughened obviously by UAR network synthesized with PPO having low molecular weight (Mn=400), i.e., the impact strength increased appreciably and the tensile strength was very close to that of pure epoxy network for the SIN material. Furthermore, the UAR network was greatly reinforced by epoxy network, although the phase separation morphology was observed in these SINs synthesized.