Deformation behaviour of poly(phenylene oxide)-high impact polystyrene blends

Blends of poly(phenylene oxide) (PPO) with high impact polystyrene (HIPS) have been injection moulded. Tensile dilatometry was used to study the deformation behaviour of the blends. The results showed that pure PPO polymer deforms via shield yielding whereas HIPS deforms by a crazing process. In addition, shearing was the predominant deformation mode in PPO-HIPS blends, with dilation accounting for only 2-4.5% of the total strain for blends containing up to 20 wt-% HIPS. However, cavitation of elastomeric particles led to a small increase in the volume strain of the 70:30 PPO-HIPS blend. The plastic volume strain appeared to show a significant increase for a HIPS content of 50 wt-% and above. The 50:50 PPO-HIPS blend deformed by a combination of crazing and shield yielding. This blend was observed to exhibit the highest fracture toughness. © 1997 The Institute of Materials.