Preparation and characterisation of compatibilised β nucleated polypropylene/polystyrene blends

Abstract

The β nucleated polypropylene (PP), uncompatibilised β nucleated PP/polystyrene (PS) and β nucleated PP/PS blends compatibilised with styrene–ethylene–propylene co-polymer and two kinds of styrene–ethylene–butylene–styrene co-polymers (SEBS) were prepared using a twin screw extruder. The crystallisation characteristic, melting behaviour, crystallisation kinetics, morphology and mechanical properties were investigated. The results showed that all the β nucleated PP/PS contained β crystal. Meanwhile, the compatibilisers exhibited a synergy effect with the β nucleating agent, which further increased the content of the β crystal. Mo's method can satisfactorily describe the non-isothermal crystallisation behaviour of the investigated blends, and the investigated blends had an increased crystallisation activation energy compared with the β nucleated PP. For the styrene–ethylene–propylene co-polymer and the SEBS whose styrene content was lower than 37% respectively, they dispersed in both PP and PS phases and modified the interfacial adhesion. For the SEBS whose styrene content was up to 57%, it formed a single phase independent of the PP and PS phases. The PS phase could improve the stiffness and toughness of the β nucleated PP. All the three compatibilisers further increased the toughness of the β nucleated PP/PS blend but decreased their stiffness.