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Study of the influence of molecular weight on the formation and crystallization of poly(lactic acid) stereocomplexes

Abstract:

The influence of the molecular weight on the formation and crystallization of PLA stereocomplexes was studied. Equimolar mixtures were prepared from poly (l-lactic acid) (PLLA) and poly (d-lactic acid) (PDLA) in solution. The thermal properties were studied by differential scanning calorimetry (DSC) and compared with the corresponding PLA homopolymers. The melting temperatures of the samples of PLLA / PDLA were higher compared to the homopolymers, indicating the formation of a more stable crystalline structure characteristic of stereocomplexes. It was also found that the stereocomplexes crystallize faster than homopolymers. Moreover it was found that upon increasing the molecular weight of the homopolymers, glass transition temperatures and melting were increased and the crystallization kinetics exhibited a complex trend.