Deconvolution Analyses of Differential Scanning Calorimetry Profiles of β-Crystallized Polypropylenes with Synchronized X-ray Measurements

Phase transformations during heating of β-crystallized isotactic polypropylenes were investigated by simultaneous SAXS, WAXD, and DSC measurements. The isotactic polypropylene samples containing the larger amount of β-form crystals were prepared by a temperature-gradient method or with the used of a nucleating agent. DSC deconvolution analysis successfully reproduced the duplicated endotherms and exotherms for both samples, considering WAXD and SAXS changes with heating. The obtained results indicated characteristic phase transformations during heating, including the temporary melting of the initial β-form and synchronized recrystallization into the α-form before the final melting of α-form crystals.