Improvement of adhesive properties of modified epoxy–novolac resin by acrylonitrile–butadiene rubber grafted poly(chromium methacrylate)

Abstract

The purpose of this work was to improve the adhesive properties of modified epoxy–novolac resin by acrylonitrile–butadiene rubber (NBR) grafted poly(chromium methacrylate). Chromium methacrylate was prepared by reaction of basic chromium sulfate with sodium methacrylate. Acrylonitrile–butadiene rubber grafted poly(chromium methacrylate) (GNBR) was successfully prepared by solution graft copolymerization to improve the adhesive properties of epoxy–novolac resin. In this copolymerization, the highest graft efficiency was obtained when 50 wt% of chromium methacrylate and 50 wt% of NBR are used for 4 h at 75 °C. The modified epoxy–novolac adhesive (GNBR–epoxy–novolac resin) was prepared by incorporation of GNBR into epoxy–novolac resin. Their chemical structures were characterized by Fourier transform infrared spectroscopy (FTIR) and the thermal properties were analyzed by thermogravimetry (TGA). The mechanical properties of GNBR–epoxy–novolac resins at both room temperature and 233 K were tested. The tensile strength, Young's modulus and failure strain of GNBR–epoxy–novolac resins were estimated from the tensile stress–strain curves and the lap shear strength (LSS) were evaluated using aluminum adherents, and the results showed that they were significantly improved. This is significant because it is one way to improve the disadvantage of high brittleness of epoxy–novolac adhesive.