Crystallization behavior and melting characteristics of wollastonite filled β-isotactic polypropylene composites

In order to obtain wollastonite filled β-iPP composites, wollastonite treated with pimelic acid (W*) were prepared with various mass ratios of wollastonite/pimelic acid (W/PA). The crystallization behavior, melting characteristics and β-nucleating ability of iPP composites filled with wollastonite (W) and W* were investigated by DSC and XRD. The results indicated that addition of wollastonite increased the crystallization temperatures of iPP, but the crystallization temperatures of iPP in iPP/W* composites were higher than those of iPP/W composites, which proved that the β-nucleation of W* is stronger than untreated wollastonite. Although iPP/wollastonite composites mainly form α-phase iPP, modification of wollastonite by PA significantly enhanced nucleation of β-phase iPP. The β-nucleating ability of W* depend on the amount of formed calcium pimelate, therefore the β-phase contents of β-iPP/W* composites increased with increasing W* content and decreasing mass ratio of W/PA. Moreover, there exist different critical mass ratios of W/PA for preparation of β-iPP composites filled with different W* contents with highest β-phase content and low cost.