The effect of poly(4-methyl-1-pentene) on the nonisothermal crystallization kinetics of polypropylene

The crystallization behavior during cooling from a melt was investigated for polypropylene (PP), poly(4-methyl-1-pentene) (PMP), and their blends (PP 70 wt%). PMP did not affect the crystallization temperature of the a-form of PP under the non-isothermal condition and vice versa. On the other hand, the existence of PMP tends to prevent the formation of the conformational disordered phase of PP at a cooling rate of 50-100 K s(-1). Regarding the crystallinity of PP, there were no differences in the heat of fusion between PP and PP/PMP blends that were prepared with the same cooling rate from the melt. The existence of PMP does not affect the total crystallinity of PP that was prepared by continuous cooling from the melt. Comparing the crystallization rate during cooling, PMP is at least 100 times faster than PP.