The effect of thermal history of polyamide 6 on the crystallization and melting behavior of β-nucleated polypropylene/polyamide 6 blends

It has been proved that the effect of amorphous polymer as the second component on the β-nucleating effect of β-nucleated isotactic polypropylene (iPP) blends was less than that of the crystalline polymers. We guess that it is the crystallinity of the second component that affects the β-nucleating effect. In order to prove this hypothesis, the blends of β-nucleated iPP and polyamide 6 (PA6) were prepared by melt compounding in this study. Cooling rate, crystallization temperature, crystallization time, annealing temperature and annealing time were used to control the crystallinity of PA6 phase, and the effect of PA6 crystallinity on the crystallization and melting behavior was studied, in turn its effect on the β-nucleating effect of iPP phase was explored. The results indicated that β crystal content markedly decreased with the increase of PA6 crystallinity, which proved that PA6 crystallinity controls the α-nucleating effect and suppresses the β-nucleating effect of the β-nucleating agent in the β-nucleated iPP blends, leading to a significant decrease in β crystal content. Therefore, decreasing the crystallinity of the second component in the β-nucleated iPP blends is a feasible method to weaken α-nucleating effect of the second component and an effective way to obtain β-nucleated iPP blend with high β crystal content.