Mechanical Properties and Morphology of Blends of Hyperbranched Polymer with Polypropylene and Poly(vinyl chloride)

Hyperbranched poly(amide-ester) (HBP) has a compact, highly branched, threedimensional structure , which has a high density of functional end groups and inherently low viscosity. The HBP additives are able to behave as lubricants during processing and as compatibilizing agents in the blend . In this work , polypropylene/poly(vinyl chlor ide)/hyperbranched poly(amide-ester) (PP/PVC/HBP) blends were prepared by melt mixing; the PP/PVC (80/20 mass ratio) blends were investigated in detail. Mechanical and rheological properties were measured . The tensile strength of the blends reached the maximum value when the content of hyperbranched poly (amide-ester) was 3 phr; the impact strength of the blends was small changed as that of pure PP/PVC. The viscosity of the PP/PVC/HBP blends was higher than that of pure PP/PVC blends, whereas the viscosity of the PP/PVC/HBP blends dropped with added more HBP. The scanning electron microscopy (SEM) showed that a two-phase morphology was characteristic of blends and dual-continuous morphology of PP/PVC/HBP (80/20/3) blend. With more or less HBP, the PVC spherical droplets of the minor phase dispersed in a PP continuous matrix phase, whereas there was a large difference between/among the minor-phase particle size. The SEM photos also confirmed that HBP could enhance the adhesion at the interface and reduce the phase separation of PP/PVC blend. The tensile strength of blends was in accord with morphology and DSC of blends.