Crystallization and melting kinetics of low tacticity polypropylene in relation to preformed nuclei and uncrystallizable defects

Fast scanning calorimetric experiments were carried out on low-isotacticity polypropylene (LT-PP) to evaluate the effect of pre-nucleation below the glass transition temperature (also known as Tammann's crystal nuclei development method) on the kinetics of crystallization and melting. The melting kinetics of secondary crystal-lized LT-PP was not affected by the presence of crystal nuclei, although the isothermal crystallization rate of LT -PP was accelerated by increasing the amount of crystal nuclei. The maximum primary crystallization decreased with increasing amounts of crystal nuclei. This behavior can be explained by the formation of uncrystallizable defects between the crystalline domains.

Automated summary

Fast scanning calorimetric experiments were conducted to investigate the effect of pre-nucleation on the crystallization and melting kinetics of low-isotacticity polypropylene (LT-PP). The presence of crystal nuclei accelerated the isothermal crystallization rate of LT-PP, but had no effect on the melting kinetics of secondary crystallized LT-PP. Moreover, increasing amounts of crystal nuclei resulted in a decrease in the maximum primary crystallization, which can be attributed to the formation of uncrystallizable defects between the crystalline domains.