Effect of nanosilica-based immobile antioxidant on thermal oxidative degradation of SBR

Abstract

A new kind of nanosilica-based immobile antioxidant (RT-silica) consisting of nanosilica, antioxidant intermediate p-aminodiphenylamine (RT) and silane coupling agent 3-glycidoxypropyltrimethoxysilane (KH-560) was successfully synthesized via a grafting reaction in our laboratory. It was revealed that the anti-oxidation performance of the SBR/RT-silica composite was far superior to that of the SBR/silica composite, especially at high temperature, based on the results of non-isothermal oxidation induction time (OIT) tests. The calculation of protection factors (PFs) based on two non-Arrhenius temperature functions showed that silica possessed an acceleration effect on the aging of the SBR matrix. According to the results of tensile tests, the SBR/RT-silica composites exhibited more preeminent mechanical properties and residual rates during accelerated aging, in comparison with the SBR/silica composites. The affections of RT-silica on the cross-linking network of the SBR matrix were investigated via a tube model, demonstrating that RT-silica can't change the cross-linking density, but can induce the chain entanglement of rubber molecular chains. Moreover, the calculated values of degradation activation energy of SBR composites via the Kissinger–Akahira–Sunose (KAS) method and Friedman method showed that RT-silica changed the thermal-oxidative aging mechanism of the SBR matrix.