Studies On The Super-Toughened Mechanism Of Poly-(phenylene Oxide) Alloy And The Relationship Between Its Micro-Morphology And The Sub-cluster Parameters

In this paper, poly(phenylene oxide) (PPO) was modified by mixing it with various tougheners and compatibilizers in a twin-screw extruder. Processing parameters such as temperature and shear condition were controlled to achieve modification both physically and chemically. This research work was carried out in two stages to prepare super-toughened PPO alloys. Stage 1: The Toughening of PPO/PA6 AlloysThree elastomers were tried to improve the impact strength of PPO/PA6 alloys, including styrene/ethylene-butylene/styrene triblock copolymer (SEBS, Kraton G 1651), ethylene/octene-1 copolymer (POE, Engage 8150), and maleic anhydride grafted SEBS (SEBS-g-MA, Kraton FG 1901). The resulted alloys combine the high Tg, high dimension stability, and low water absorbability of PPO and the processibility and high solvent resistance of PA6.Maleic anhydride(MA) grafted PPO (PPO-g-MA) was also prepared via melt-mixing as a compatibilizer of PPO and PA6. FTIR determination of the PPO-g-MA showed that MA was indeed grafted onto PPO chains. This compatibilizer was applied to two alloys: PPO/PPO-g-MA/PA6 and PPO/PPO-g-MA/PA6/SEBS. Characterization with transmission electron microscopy (TEM) and scanning electron microscopy (SEM) indicated that an excellent compatibilization was achieved in these alloys. The size of dispersed phase (PPO) decreased with the increase of the amount of PPO-g-MA. The impact strength of the alloys increased with the PPO-g-MA content and a brittle-tough transition was observed. These results indicated that PPO-g-MA reacted with PA6 in-situ during the extrusion and copolymers PPO-g-PA6 was produced. The point of brittle-tough transition was dependent on the content of PPO-g-MA and SEBS, which was around the PPO-g-MA amount of 25 wt%, and that of SEBS of 10-15 wt%. The Izod impact strength of 450 J/m was achieved.PPO/PA6 alloys were further toughened by MA grafted POE(POE-g-MA). The grafting product improved the compability of POE and PA6. When the amount of grafted MA was 0.46 wt%, the average size of POE domains in PA6 matrix was 0.2μm compared with 20 μm of ungrafted POE. The addition of POE-g-MA greatly increased the impact strength of the alloys, which could be as high as 650 J/m. A brittle-tough transition was also observed, which was around the POE-g-MA content of 15wt% and that of 0.2～0.5wt% grafting degree.