Mechanical properties and morphology of a PP/HIPS polymer blend compatibilized with SEBS

In this work the effect of a 2-7% w/w styrene-b-ethylene-co-butylene-b-styrene triblock copolymer (SEBS) addition on the properties of a 70:30 polypropylene/high impact polystyrene (PP/HIPS) polymer blend was investigated. Tensile and impact properties, the Vicat temperature and blend morphology were determined as a function of SEBS content. Processing was carried out in a twin-screw intermeshing counter-rotating extruder and the samples were compression moulded. Our results indicate that the SEBS addition, albeit promoting very slight increases on tensile strenght and modulus, led to increases on the elongation at break and impact strenght of the blends, and the Vicat temperature of the blends was higher than that of HIPS. The SEM analysis showed that SEBS addition promotes a significant reduction on particle size, which was taken as an indication that SEBS exerted an emulsifying and stabilizing effect on the morphology of the PP/HIPS blend under investigation. The best overall properties were obtained at 5 wt.% SEBS content.

Polymer blend; compatibiliser; polypropylene; high impact polystyrene; SEBS; HIPS