The β-nucleating effect of wollastonite-filled isotactic polypropylene composites

Wollastonite (W) with β-nucleating effect (β-W₁₀₀) for iPP crystallization was obtained through reaction between Ca²⁺ in wollastonite and pimelic acid (PA) and the β-iPP composites filled by different content of β-W₁₀₀ were prepared. The effect of PA and wollastonite contents on β-nucleation, crystallization and melting behavior, and crystalline morphology of W and β-W₁₀₀-filled iPP composites was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction, and polarizing optical microscopy. The results indicated that incorporation of W and β-W₁₀₀ increase the crystallization peak temperature of iPP due to its heterogeneous nucleating ability. And iPP/W composites predominantly crystallize in the α-phase iPP and iPP/β-W₁₀₀ composites in the β-phase iPP. The results of DSC multi-scanning in same and different melting temperatures showed that β-W₁₀₀ not only has strong heterogeneous β-nucleating effect but also DSC multi-scanning in same and different melting temperatures has no influence on the heterogeneous β-nucleating effect of β-W₁₀₀. The β-iPP containing high wollastonite content with high β-phase content can be easily prepared.