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.