Isothermal crystallization and chain mobility of poly(L-lactide)

Isothermal melt crystallization of poly(L-lactide) (PLLA) has been studied in the temperature range of 90 to 135°C. A maximum in crystallization kinetic was observed around 105°C. A transition from regime II to regime III is present around 115°C. The crystal morphology is a function of the degree of undercooling. At crystallization temperatures (Tc) below 105°C, further crystallization occurs upon heating; this behavior is not detected for Tc above 110°C. The analysis of the heat capacity increment at glass transition temperature (Tg) and of dielectric properties of PLLA indicates the presence of a fraction of the amorphous phase which does not relax at the Tg, and the amount of this so-called rigid amorphous phase is a function of Tc. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 911–919, 1997