Non-isothermal crystallization kinetics of β-nucleated isotactic polypropylene

Isotactic polypropylenes (iPP) samples were incorporated with two beta-nucleating agents (NT-A and NT-C), respectively, and their non-isothermal crystallization and subsequent melt behaviors were investigated by means of differential scanning calorimeter. Jeziorny, Ozawa, and Mo methods were used to analyze non-isothermal crystallization kinetics of pure iPP and beta-nucleated iPP samples. The activation energies (Delta E) of non-isothermal crystallization were calculated by Kissinger method. And the nucleation activities were calculated according to the Dobreva method. It is found that the crystallization temperature decreases and the crystallization rate increases with increasing cooling rate. The crystallization temperature and crystallization rate of nucleated iPP are higher than those of pure iPP. The order of Delta E is NT-A/iPP > pure iPP > NT-C/iPP. NT-C is more efficient than NT-A as a beta-nucleating agent. But the non-isothermal crystallization kinetics of alpha- and beta-phases cannot be determined separately. The present results should be considered with caution.