Abstract: PP/talc and PP/CaCO3 composites were prepared via melt mixing method using Haake rheometer. The isothermal crystallization behavior of PP and the composites were investigated using differential scanning calorimetry(DSC). The effects of talc and calcium carbonate on the isothermal crystallization behavior of PP were compared. It showed that all the Avrami indexes of PP, neat or in the composites, were lower than 2.3, which showed that both homogeneous and heterogeneous nucleation mechanisms occurred in these systems. The crystallization rate decreased with increasing crystallization temperature. It was found that the effect of talc promoted the heterogeneous nucleation significantly, whereas the effect of CaCO3 was moderate.

Key words: polypropylene, talc, CaCO3, isothermal crystallization