Roles of unsaturated polyester in the epoxy matrix system

A study of the interpenetrating polymer network (IPN) as a polymer blend matrix was carried out using different compositions of unsaturated polyester (UP) to epoxy (EP) resins. It was observed that 5 wt% UP in the blend provides maximum mechanical properties, particularly the impact strength for optimum casting. Fourier transform infrared (FT-IR) spectroscopy was used to investigate the intermolecular hydrogen bonding and functional group change. In this work, changes of physical property, e.g., viscosity and specific component of interfacial tension were evaluated before and after cure, respectively. Increase of the physical properties was observed in 5 wt% UP in the blend, probably due to the effects of hydrogen bonding, resulting in higher toughness properties of the casting specimens.