Isothermal melting behavior of poly(L‐lactic acid)

The isothermal melting behavior of poly(L‐lactic acid) spherulites has been studied in order to understand the mechanism of melting using hot‐stage microscopy. When the periphery of the spherulite melts or shrinks, the central portion undergoes thickening as a result of which the melting or shrinking rate is not linear. Annealing studies at 448 K reveal that there is an increase in melting temperature and heat of fusion with annealing time, suggesting an increase in lamellar thickness. The high activation energy (828 kJ/mol) obtained in this investigation suggests the highly complex nature of the melting process wherein both melting and thickening occur