聚苯醚与SEBS及SEBS-g-MA共混物的亚微相态和流变性能

采用透射电子显微镜(TEM)研究了聚苯醚(PPO)与苯乙烯-乙烯-丁二烯-苯乙烯嵌段共聚弹性体(SEBS)及其马来酸酐接枝共聚物(SEBS2g2MA)共混物的亚微相态,发现对于PPO/SEBS共混物,SEBS在PPO基体中呈现条形分散相的“海—岛”结构。而在PPO/SEBS-g-MA共混物中,当SEBS-g-MA含量超过10%(质量分数)后,在PPO基体中呈现双连续相的网络结构。这种双连续结构的形成使SEBS2g2MA能够有效地增韧PPO。共混物的流变性能研究显示,PPO/SEBS共混物的表观粘度在所有剪切速率范围内均高于纯PPO,SEBS含量越高,表观粘度也越大;而PPO/SEBS-g-MA则显示完全相反的趋势。出现上述现象的主要原因是两种弹性体中的EB橡胶链段分子量不同和PPO与两种弹性体的相容性差异所决定的。

Morphology and rheological properties of blends of poly(phenylene oxide) with SEBS and maleated SEBS

The morphology of poly(phenylene oxide)(PPO) blends with styrene ethylene-co-butadiene styrene block copolymer(SEBS) and a version grafted with maleic anhydride(SEBS-g-MA) was investigated using a transmission electron microscopy(TEM). SEBS was found to show a typical "sea-island” structure in PPO domain for PPO/SEBS blends. However, SEBS-g-MA demonstrated a network structure in PPO matrix for PPO/SEBS-g-MA blends. Toughness improvement for PPO blends with SEBS-g-MA was contributed to stress releasing in micro-cavity. The rheological properties study revealed that the apparent viscosity of PPO/SEBS blends increased with the increasing of SEBS content at all non-Newtonian shear rate range, but opposite for PPO/SEBS-g-MA blends. The main reason of this phenomenon is due to the difference of the miscibility between PPO and SEBS or SEBS-g-MA, and melt viscosity of SEBS and SEBS-g-MA.