Melting behavior of poly(butylene succinate) during heating scan by DSC

The melting behavior of isothermally crystallized poly(butylene succinate) (PBS) has been investigated using differential scanning calorimetry (DSC) a nd wide-angle X-ray analysis. The samples crystallized between 80 degrees C to 100 degrees C show middle endotherm at the position just before the hig h exotherm, while the others under 80 degrees C show two endotherms (low an d high). From the results of the melting peak vs. crystallization temperatu re plot, it was suggested that the middle endotherm corresponds to the melt ing process of the original crystallites and the high endotherms to the mel ting process of the recrystallized ones. As the DSC heating rate was increa sed, the peak temperature of the low and middle endotherms increased and th at of the high endotherm decreased, indicating that the low endotherm was d ue to the original crystallites as well as the middle endotherm. Consequent ly, in the heating scan of PBS, the existence of two kinds of morphological ly different crystallites as well as the process of melting and recrystalli zation becomes evident. (C) 1999 John Wiley & Sons, Inc.