Multiscale physicochemical characterization of a short glass fiber–reinforced polyphenylene sulfide composite under aging and its thermo-oxidative mechanism

Abstract

In this paper, the thermo-oxidation for a short glass fiber–reinforced polyphenylene sulfide (PPS/GF) composite was experimentally and theoretically studied by a wide range of physicochemical and mechanical techniques. The accelerated thermal aging temperatures were fixed at 100°C, 140°C, 160°C, 180°C, and 200°C. Firstly, the results of weight loss under aging indicate the formation of volatile products because of chain scission of end groups. Also, Fourier-transform infrared spectroscopy (FTIR) results suggest that the formation and accumulation of carbonyl group arising from the formation of hydroperoxides in oxidative propagation process. In all cases of different thermal oxidation temperatures, it is hard to observe some significant change about the concentration of carbonyl group during the induction time. This induction time depends inversely on the oxidation temperature. Moreover, the cross-linking and chain scissions exist together according to the results of rheological results and it is easier to see the cross-linking phenomenon at the beginning of oxidation while the chain scissions are more pronounced, with the oxidation process developing further. In aspect of mechanical properties, σ max increases at the beginning of oxidation because of cross-linking, and subsequently, the σ max always decreases because of thermo-oxidation of the PPS matrix. In addition, the detailed thermo-oxidation processes are fully discussed in the end of this study. A mechanistic schema has been proposed to present different oxidation reactions of PPS polymer and then a kinetic model has been extracted from this mechanism. Afterwards, the model has been verified by experimental results at different temperatures.