Property/Morphology Relationships in SEBS-Compatibilized HDPE/Poly(phenylene ether) Blends

High density polyethylene suffers from poor mechanical properties at elevated temperatures (e.g., above 60 degrees C) due to its relatively low melting point and, particularly, low heat deflection temperature (HDT), which limits its usage in a wide range of applications. This work intends to improve the HDT of high density polyethylene (HDPE) by melt blending with two poly(2,6-dimethyl-1,4-phenylene ether) (PPE) resins of different molecular weights at different compositions and using two styrene-ethylene/butylene-styrene (SEBS) triblock copolymers of different viscosities to compatibilize the resulting blends. HDT values were found to increase linearly with PPE content but decreased as the concentration of the compatibilizer increased. Morphological analysis of HDPE/PPE blends with various amounts of SEBS as investigated by scanning electron microscope (SEM) confirmed the compatibilization effect of SEBS in HDPE/PPE blend systems. The mechanical properties suggest that HDPE/PPE blends are somewhat stable systems at low PPE content; uncompatibilized HDPE/PPE maintained good ductility up to 25% PPE content when the PPE used is of a high molecular weight.