A novolac epoxy resin modified polyurethane acylates polymer grafted network with enhanced thermal and mechanical properties

This paper describes the synthesis of novolac epoxy resin modified polyurethane acrylates (EPUAs) for generating a grafted polymer network, which is different from the conventional interpenetrating polymer networks (IPN). It starts with preparing epoxy acrylate resins (EA) by the ring-opening reaction of novolac epoxy resin (EP) and acrylic acid (AA). Epoxy acrylate copolymers (EPAcs) with hydroxyl groups were prepared by the copolymerization of EA and acrylic monomers. EPUAs were obtained by reacting EPAcs with curing agents (polyisocycanate HDI-trimer and phthalic anhydride). The chemical structures of the obtained EA and EPAcs were characterized by Fourier-transform infrared spectroscopy (FTIR) and H-1 nuclear magnetic resonance spectra (H-1 NMR). The influence of EP on chemical and physical properties of EPUAs, including fracture surface morphology, thermal stability, tensile strength, elongation at break, glass transition temperature (T-g), cross-linking density, shore hardness, water absorption, adhesion, etc., were investigated as well. It is demonstrated that the incorporation of EP into EPUAs greatly enhances the above physico-chemical properties of EPUAs.