Novel Method for Preparation of Polypropylene Blends with High Melt Strength by Reactive Compounding

Ultrafine full-vulcanized polybutadiene rubber(UFBR) with particle sizes of ca. 50-100 nm were used for modifying mechanical and processing performances of polypropylene(PP) with PP-g-maleic anhydride(PP-g-MA) as a compatibilizer for enhancing the interfacial adhesion between the two components. The morphology, dynamical rheology response and mechanical properties of the blends were characterized by means of SEM, rheometer and tensile test, respectively. The results show that the ternary PP/UFBR blends compatibilized with PP-g-MA possess rheological behaviors like highly branched PP, while no obvious strain hardening is observed in its control binary PP/UFBR blends, a low level of PP-g-MA in PP/UFBR blends can even endow the material with rheological characteristics of high melt strength materials like highly branched PP. The enhancement interfacial interaction between the UFBR particles and PP matrix accounting for the rheological behavior of compatibilized blends and effectiveness of PP-g-MA were proposed and proved.