Isothermal crystallization experiments were performed with a TA-Q200 DSC instrument (TA, New Castle, PA, USA) using nitrogen as the purge gas, according to the procedure described in the literature. The sample (4–6 mg) was initially heated to 200 °C at a rate of 10 °C/min and held for 5 min to remove the thermal history of the crystallizable phase. Subsequently, the sample was rapidly cooled (−60 °C/min) to a designated crystallization temperature (Tc) and held at this temperature until the end of the exothermic crystallization. The heat flow during the isothermal crystallization process was recorded as a function of time. Tc was chosen as 137 °C in this experiment. The amounts of heat generated during the development of the crystal phase were recorded and analysed according to the typical equation used for evaluating the degree of relative crystallinity (Xt): (1)Xt=∫t0t(dHdt)dt∫t0t=∝(dHdt)dt where t0 and t = ∞ are the times at which the sample reached isothermal conditions (as indicated by a flat baseline after an initial spike in the thermal curve) and the time at which the dominant sharp exothermic peak ends, respectively. H is the enthalpy of crystallization at time t. After isothermal crystallization, the sample was heated to 200 °C, and the crystal melting temperature (Tm), indicated by the maximum of the endothermic peak, was recorded.