Tailoring performance of PP/HIPS/SEBS through blending design

Abstract

In this work blending design was applied to development of polypropylene (PP)/high impact polystyrene (HIPS) blends using styrene-(ethylene/butylene) styrene (SEBS) as compatibilizing agent. PP/HIPS/SEBS (50/40/10%) which presented the best balance between impact strength and stiffness was selected, aiming to investigate the effect of five blending sequences on morphology, mechanical, thermomechanical and thermal properties. Blends were initially compounded in a corrotational twin screw extruder and later on extruded granules were injection molded. Acquired results showed the morphology and impact of compatible blends were distinct and depend on blending sequence, i.e., being PP and SEBS firstly extrusion premixed followed by HIPS addition in the second extrusion step there was increase in impact strength, thermal deflection temperature (HDT), and thermal stability compared to PP and PP/HIPS, contrary, when HIPS and SEBS were firstly extrusion premixed and PP was added in the second extrusion step excessive reduction of HIPS particle size was verified; and additionally HDT, impact strength and thermal stability decreasing were observed compared to the other sequences. Summing up, PP/HIPS/SEBS properties are adjustable to specific application needs modifying the blending route.