Phase transition and melt-recrystallization behavior of poly(butylene adipate) investigated by simultaneous measurements of wide-angle x-ray diffraction (WAXD) and differential scanning calorimetry (DSC)

Abstract

Abstract: Simultaneous measurements of wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) were carried out to investigate the phase transition and melting behaviors of polyfbutylene adipate) (PBA). Thermal expansion changes along the a and b axes of the β form unit cell are different from each other during the heating process. At the beginning of the β to αH (high-temperature α phase) phase transition, the β phase melts very fast, while the recrystallization of the αH phase is delayed and slowed. With the further increment of the temperature, the melting rate of the β phase slows down, while the recrystallization of the phase accelerates. The diffraction peak intensity ratios of the β(020):β(110) and αH(020):αH(110) diffraction peaks during the first heating process have similar value. However, the above value is different from the value of α(020):α(110) during the following melt-crystallization process. This difference comes from the different orientations of the crystal lattices of the α and αH(β) crystals to the substrate plane, which indicates that the β phase inherits the orientation of the phase during phase transition and the orientation of αH form crystals is different from the α form crystals that crystallized from the melt.