Isothermal crystallization kinetics, morphology, and crystalline structure of polypropylene/poly(4‐methyl‐1‐pentene) blends

The isothermal crystallization kinetics of polypropylene (PP) in poly(4-methyl-1-pentene) blends were investigated by comparing the blend results with those of the PP homopolymer. Fast scanning calorimetry-optical microscope studies were carried out to determine the crystallization rate and microscale morphology during crystallization from the highly supercooled liquid. The crystallization rate of the blend system was faster than that of the PP homopolymer at temperatures between 50°C and 90°C. Synchrotron small angle X-ray scattering and transmission electron microscopy results showed that there were no differences in the thickness of lamellar PP or nanoscale PP morphology between the homopolymer and polymer blends. Wide angle X-ray scattering data revealed that the content ratio of the PP α form and the conformational disordered PP phase did not change between both samples. However, the crystalline lattice size of PP decreased in the blend systems. The increment of crystallization kinetics of the blend system is explained by a Gibbs free energy diagram.