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, threedimensionalstructure, 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 chloride)/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 continu ous 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.