Crystallization behavior of isotactic polypropylene containing a fibrous nucleating agent in a flow field

The crystallization behavior of isotactic polypropylene containing a fibrous nucleating agent in a flow field was investigated using a polarized optical microscope equipped with a parallel-plate shear device. The addition of the fibrous nucleating agent greatly enhanced the crystallization rate, although isotactic polypropylene crystallization without the nucleating agent was enhanced after exposure to shear flow at a high shear rate. The sample with the nucleating agent demonstrated high molecular orientation to the flow direction after shear flow, even at a low shear rate. This was attributed to the formation of a pseudo shish-kebab structure, in which the fibrous nucleating agent acts as the shish. Moreover, the high level of molecular orientation without spherulitic morphology was responsible for the reduced light scattering, which resulted in good transparency.