Characterization of liquid carboxy terminated copolymer of butadiene acrylonitrile modified epoxy resin

Toughening of epoxy cresol novolac resin (ECN) by carboxy terminated acrylo nitrile-co-butadiene (CTBN) liquid functional rubber have been studied. Wid e angle X-ray scattering (WAXS) has been utilized to evaluate average molec ular interchain spacing (< R >) from the strong maximum in the diffraction scan using Bragg's equation. The half-width (< HW >) of the maximum was use d to qualitatively describe the distribution of < R >. An increase in < R > value signifies formation of a separate packing order as well as increase in the free volume. Fouler transform infrared spectroscopy (FTIR) studies c onvincingly establish that the interaction between oxirane group of epoxy a nd carboxyl group of CTBN are responsible for characteristic peak shifts in the blends compared to individual polymers. Physicomechanical properties o f the blends e.g., the tensile, flexural and impact strengths showed an opt imum concentration of CTBN (10 wt%) into ECN, which can offer maximum tough ening. Cross sections of the composite specimens failed during impact testi ng have been critically studied through scanning electron microscopy (SEM) to gain insight into the mechanism of toughening and phase morphology.