Improved mechanical responses of GFRP composites with epoxy-vinyl ester interpenetrating polymer network

Abstract

Present investigation deals with development of glass fiber reinforced polymer (GFRP) composite with a matrix composed of a polymer blend of epoxy and vinyl ester. The evolved Interpenetrating polymer network (IPN) formed due to blending of the polymers resulted in improved tensile, flexural and interlaminar shear properties of the hybrid composite than that of both glass fiber/epoxy (GE) and glass fiber/vinyl ester (GVE) composites. Resin burn-off test revealed that the glass fiber volume fraction to be almost identical in all three composite laminates, which was ~45%. The role of curing temperatures (140, 170, 200 and 230 °C) on the cure kinetics of the composites was examined based on the flexural properties of the composites, which is also supported with the dynamic mechanical thermal analysis (DMTA) results. The glass fiber reinforced epoxy-vinyl ester interpenetrating polymer network (GEVIPN) composite led to 21.83%, 22.54% and 13.43% improvement in interlaminar shear strength (ILSS), tensile and flexural strength respectively, over GE composite at optimal post cure temperature. Further, chemical restructuring of GEVIPN composite was analysed by Fourier transform infrared spectroscopy (FTIR). From scanning electron microscopy (SEM), it was comprehended that strong interfacial bonding between the matrix and fiber made GEVIPN composite exhibit better mechanical properties.