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Nonisothermal crystallization of poly(L-lactide)/olive stone flour composites

Due to the fact that the resulting physical properties are strongly dependent on the morphology formed and the extent of crystallization during processing, studies of the kinetics of polymer crystallization are of great importance in polymer processing. In this work, the crystallization kinetics of poly(L-lactide) (PLLA) in poly(L-lactide)/olive stone flour (PLLA/OSF) composites was studied under nonisothermal condition. PLLA was blended with various amounts of OSF filler (0, 10, 20 and 30 weight parts regarding to PLLA). Nonisothermal crystallization was performed using differential scanning calorimeter (DSC 823e, Mettler-Toledo) equipped with intracooler. Sample mass was approx. 19 mg. The samples were heated from 25°C to 200°C at 20°Cmin-1 and maintained at 200°C for 3 min to destroy any crystals nuclei. The samples were then cooled to 25°C at different cooling rates: 1, 2, 5 and 10°Cmin-1. To determine the kinetic parameters of the nonisothermal crystallization process kinetic models after Avrami and Friedman were applied. Performed analysis revealed the existence of two mechanisms of nonisothermal crystallization of PLLA in all samples. The obtained results show that the crystallization process of PLLA in the composites was affected by the content of olive stone flour as well as the crystallization conditions.

poly(L-lactide); olive stone flour; nonisothermal crystallization kinetics; differential scanning calorimetry

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