Enhanced Charpy impact strength of epoxy resin modified with vinyl‐terminated polydimethylsiloxane

This article deals with enhancement of the toughness of epoxy resin (ER) based on diglycidyl ether bisfenol A by either polydimethylsiloxane (PDMS) or vinyl‐terminated polydimethylsiloxane (VT‐PDMS). To improve the compatibility of these two phases, dicumylperoxide (DCP) was used as a compatibilizer. It was established that only specific composition of the components can lead to enhancement of ER toughness without significant reduction of storage modulus, Tg, and interphase adhesion. The highest impact strength was recorded for ER with VT‐PDMS (10 wt %) and DCP (2 wt %) due to increased interfacial compatibility between two phases, which was proved by 1H NMR and dielectric spectroscopy. Critical ductile brittle transition occurring between 10 and 15 wt % of rubber was observed by both morphological and dynamic mechanical analysis studies.