Advancing thermo-oxidative stability in silicone rubber with cerium-tin complex oxide
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 CeO 2 . 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 CeO 2 , SnO 2 , 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 CeO 2 and SnO 2 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.
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