The effect of epoxy–silicone copolymer content on the thermal and mechanical properties of cured epoxy resin modified with siloxane

Abstract

In this research, a bisphenol-A type epoxy resin (DGEBA) was modified with epoxy-block-silicone copolymers and hydroxyl-terminated silicone oligomers by physical blending and a chemical reaction, respectively. The chemical structure of the siloxane-bridged epoxy resin terminated by –OHs was characterized by Fourier transform infrared spectroscopy (FTIR), ¹H-NMR and an epoxy equivalent weight (EEW) test. Both the samples showed better elongation at break and impact strength than neat resin. The TGA-FTIR results revealed that the residue of the modified epoxy resin at 600 °C increased with the increase in siloxane content, but the thermal stability was slightly reduced compared with that of the neat epoxy resin. Morphology studies indicate that the increase in izod notched impact strength is due to the suitable diameter of silicone phases because of the silicone toughening effect. Therefore, it is believed that the modified epoxy resin, with good toughness and high thermal residual weight, will have potential applications in anti-corrosion coatings and structure bonding materials.