Crystallization and melting behavior of polypropylene (PP) in (vulcanized nanoscale polybutadiene rubber powder/PP) polymer-nanocomposites

Radiation vulcanized polybutadiene rubber powder (PBRP) was prepared and blended with polypropylene (PP). Melting behavior and isothermal crystallization kinetics of PP and prepared polymer-nanocomposites were investigated by differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). It was found that the addition of PBRP increased the melting (Tm) and crystallization (Tc) temperatures, as well as the crystallization rate of PP. By study on isothermal crystallization kinetics of PP, in terms of the Avrami equation, the Avrami exponent n for the pure PP was determined about 2. Using and increasing the amount of PBRP in the nanocomposites increased the n value up to 3.4; indicating a heterogeneous nucleation followed by a three-dimensional crystal growth. WAXS results showed that the existence of PBRP had no effect on the α-form of PP crystals. However, the use of PBRP promoted the crystals to become perfect and resulted in a larger crystallite size.