Simultaneous reinforcing and toughening of high impact polystyrene with a novel processing method of loop oscillating push–pull molding

• A novel LOPPM process is proposed to simultaneously reinforce and toughen HIPS.
• The oriented pebble-like salami rubber particles in HIPS are formed by LOPPM.
• PS contained by PB phase is stretched to nanoscale size by LOPPM.
• The impact strength and tensile strength of the LOPPM-HIPS significantly increase.
• The mechanism of simultaneously reinforcing and toughening of HIPS is explained.

This article reports a novel polymer processing method of loop oscillating push–pull molding (LOPPM), which was used to reinforce and toughen high impact polystyrene (HIPS) simultaneously via introducing a dynamic flow field with an oscillatory shear in HIPS molding process. It is found that the impact strength and tensile strength of the LOPPM-HIPS have been significantly increased by 467% and 70% compared with those of the conventional molding HIPS (CM-HIPS), respectively. The morphology of the HIPS samples was characterized by TEM and SEM to investigate the increases. The results revealed that the salami rubber particles in the LOPPM-HIPS turned into pebble-like shapes and formed a special orientation structure. Based on the relationship of structure and properties, the mechanism of the simultaneously reinforcing and toughening was proposed.