Enhancement of the physio/chemical and adhesion properties of SBR: Novolac blend by addition of nano-silica

Abstract

The research focuses on the preparation of blending styrene-butadiene rubber (SBR) with Novolac and SBR: Novolac: Silica nanocomposites. The performance and properties of the nanocomposites were analysed using SEM, contact angle, FT-IR, DSC, XRD and peel adhesion tests after reinforcement with nano-silica. The results indicate that Novolac resin reduces scorch and optimises curing times. The viscosity, maximum torque and cure rate index were increased as the loading levels of Novolac increased up to 20 phr. Further, it enhances crystallisation, thermal stability and swelling resistance. Significant reduction in scorch and cure times was observed, while viscosity, maximum torque and cure rate index increased with silica loading up to 6 ppm due to improved homogeneity and dispersion. In addition, increasing the contact angle indicates improved crystallinity, while thermal stability exceeded that of the SBR: Novolac blend. The interaction between Si-OH groups on SiO₂ nanoparticles and carboxyl groups in phenolic resin increased crosslinking density by 5% and 47%, while the swelling rate decreased by 3% and 50% for SBR: Novolac and SBR: Novolac: Silica, correspondingly. According to the results, the adhesion strength between nanocomposites and the copper/iron wires increased by 495% and 900%, respectively, with nano silica loading up to 5 phr.