Effect of Hyperbranched Poly(amide-ester) Grafted Polypropylene on the Compatibility of Polypropylene/Poly(vinyl chloride) Blends

he compatibilizing effect of hyperbranched poly(amide-ester) grafted polypropylene (PP-HBP) had been investigated in polypropylene (PP)/poly(vinyl chloride) (PVC) blends. In this work, PP/PVC/PP-HBP blends were prepared by melt mixing. Mechanical and rheological properties and phase morphologies of the blends were studied as a function of PP-HBP. The results showed that the tensile strength of the blends reached the maximum value when the content of PP-HBP was 5 phr and then dropped on the increase of PP-HBP. The impact strength of the blends showed a small change as that of pure PP/PVC blend, and the viscosity of the PP/PVC/PP-HBP blends was higher than that of pure PP/PVC when the amount of PP-HBP added was 5 phr. The viscosity of the PP/PVC/PP-HBP blends was lower than that of pure PP/PVC blend when PP/PVC blend contained PP-HBP > 5 phr. The scanning electron microscopy (SEM) showed that a two-phase morphology was characteristic of all blends. In presence of PPHBP, the PVC spherical droplets of the minor phase dispersed in a PP continuous matrix phase, whereas there was a large difference among the minor-phase particle sizes. The SEM photos also confirmed that PP-HBP could enhance the adhesion at the interface and reduce the phase separation of PP/PVC blend. The tensile strength of the blends was in accordance with their morphology. ≤