Studies on cardanol-based epoxidized novolac resin and its blends

Abstract

Cardanol-based novolac-type phenolic resin was synthesized with a mole ratio 1.0:0.5 of cardanol-to-formaldehyde using a dicarboxylic acid catalyst such as succinic acid. The cardanol-based novolac-type phenolic resin may further be modified by epoxidation with epichlorohydrin excess at 393 K in a basic medium to duplicate the performance of such phenolic-type novolacs. Carboxyl-terminated butadiene acrylonitrile copolymer (CTBN) has been studied by various researches with diglycidyl ether of bisphenol-A (DEGBA) epoxy resin and epoxidized phenolic novolac resins. The epoxidized novolac resin was blended with different weight ratios of carboxyl-terminated butadiene acrylonitrile copolymer (CTBN) and cured with a stoichiometric amount of polyamine curing agent. The formation of various products during the synthesis of cardanol-based novolac resin, epoxodized novolac resin and blending of epoxidized novolac resin with CTBN has been studied by Fourier-transform infrared (FTIR) spectroscopic analysis. Further, the products were confirmed by a proton nuclear magnetic resonance (1H-NMR) spectroscopic analysis. The number average molecular weight was determined by a gel permeation chromatography (GPC) analysis. The blend sample, having 15 wt % CTBN concentration showed minimum cure time and most thermally stable systems.