Crystallization of i-PP/CaCO₃ Composites and its Correlation with Tensile Properties

Investigation of crystallization behaviour of isoatactic polypropylene (i-PP) in i-PP/CaCO3 composites is carried out through Differential Scanning Calorimetry (DSC) and wide angle X-ray diffraction measurements. The effect of CaCO3 and its surface treatment with titanate coupling agent on nucleation and growth rate of crystallization, crystallite size distribution and crystallinity, is determined from exothermic crystallization peaks of the composites. The filler concentration dependence of crystallinity determined by both the techniques shows good qualitative agreement. Tensile properties viz. tensile modulus, yield stress and elongation were also measured as functions of filler concentration for both untreated and treated CaCO3 filled composites. Crystallinity, tensile strength and elongation decreased with increasing filler content in both the cases whereas tensile modulus increased. Crystallization parameters have been correlated with the tensile properties of i-PP/CaCO3 composites.