Advancing thermo‐oxidative stability in silicone rubber with cerium‐tin complex oxide

Abstract

In order to improve the thermal stability of silicone rubber (SR), cerium‐tin composite oxides (CeSnO‐x) are used as thermo‐oxidative stabilizer in phenyl methyl vinyl silicone rubber (PVMQ). CeSnO‐x are synthesized via the sol–gel method and characterized by scanning electron microscopy, x‐ray diffraction, and X‐ray photoelectron spectroscopy (XPS) showing that tin doping led to more oxygen vacancies in CeSnO‐x compared to CeO2. Through thermogravimetric analyzer, differential scanning alorimetry (DSC) and average activation energy calculation of PVMQ with different thermo‐oxidative stabilizer, it was found that CeSnO‐8 is outperforming CeO2, SnO2, and their mixtures in improving the thermo‐oxidative stability of PVMQ. In mechanical property tests, due to tin doping, CeSnO‐8 exhibit superior performance at all stages during thermo‐oxidative aging comparing the different effects of CeO2 and SnO2 in different aging stages. XPS of PVMQ composites investigate the mechanism by which CeSnO‐8 exhibit different effects. Fourier transform infrared spectroscopy characterizing the Si‐C and Si‐O bond changes in PVMQ composite before and after aging and the measurement of Mc explore thermo‐oxidative stabilizers' role during thermo‐oxidative aging of PVMQ. Thermogravimetry‐infrared spectroscopy comparisons between unstabilized PVMQ and CeSnO‐8‐stabilized PVMQ show that CeSnO‐8 effectively quenched radicals produced by the oxidation of the PVMQ side group, but exacerbate degradation caused by molecular chain rearrangement.