Effect of alkylated surface modified silica nanoparticles on degradation products of PP during photooxidation aging: A Py-GC-MS analysis

Introducing nano-fillers to PP matrix improves its mechanical performance, but impairs the stability and changes its aging behavior. Surface modification of nano-fillers may have further influence. To investigate the effect of alkylated surface modified silica nanoparticles on PP degradation during photooxidation aging, Py-GC-MS flash evaporation technique was applied to qualitatively analyze the degradation products and quantitatively analyze their accumulation during photooxidation aging. Thermal processing of PP composites led to thermal decomposition and oxidation before aging. During photooxidation aging, both silica nanoparticles and the alkylated surface modification promoted the oxidative degradation of PP. Oxidation products accumulated, while the aging mechanism did not change. Nine typical oxidation products with different carbon numbers were selected and their accumulation during photooxidation aging were analyzed. For C1-C6 total oxidation products, there exhibits an induction period and subsequent linear accumulation during photooxidation aging. The induction period was used to show the effect of nano-silica and its surface modification. It was shortened by introducing nano-silica and further shortened by alkylated surface modification of nano-silica.