Chemical Interaction and Phase Morphology Development of Carboxy Terminated Butadiene-co-Acrylonitrile Rubber Toughened Epoxy Blends

Abstract The nature of chemical interaction between carboxy terminated butadiene-co-acrylonitrile (CTBN), a reactive liquid rubber, and epoxy cresol novolac (ECN) resin during curing with diamino diphenyl methane (DDM) as hardener has been studied by Fourier transform infrared spectroscopy (FTIR). Blends of CTBN and ECN were withdrawn at a regular interval of 15 min for 2 h and the FTIR spectra were recorded in each case. Variations of the positions of the characteristic peaks of the oxirane group of epoxy and carboxyl group of CTBN as well as formation of several new peaks with the progress of the curing were observed. Scanning electron microscopy (SEM) was conducted in each of the above samples to study the evolution of phase morphology through growth of the rubber phase while the continuous epoxy matrix underwent curing by the hardener. The surface topography and microstructure of impact-failed toughened epoxies have also been studied with the help of atomic force microscopy (AFM).