Study of breakdown properties of SMA/MPPO composites

Abstract

To improve the processability of polyphenylene oxide (PPO) and enhance its breakdown resistance, polystyrene (PS) with a mass fraction of 30% was added to PPO for blending modification, so that the melt flow rate of the modified polyphenylene oxide (MPPO) was increased to 14.8 g/10 min. Then the styrene maleic anhydride (SMA)/MPPO composites were prepared by melt blending and injection molding by adding different contents of SMA copolymer. The results showed that the anhydride group in SMA is grafted with PPO to form SMA-g-PPO copolymer, resulting in improved compatibility between PPO and PS. The best performance of the composites was obtained at a SMA content of 1 wt.%, with a DC breakdown strength of 24.6 kV·mm−1, which was 37.4% higher than that of MPPO, and an impact strength of 33.6 kJ·m−2, which was 18.7% higher than that of MPPO. The temperatures Td and T 50 corresponding to 1% and 50% mass loss increased by 46.15 °C and 11.48 °C, respectively, when the temperature was increased by 10 °C/min in the nitrogen atmosphere.