The Confined Crystallization of Hard Segments in Butylene Terephthalate-ε-Caprolactone Segmented Copolyesters

The confined crystallization of hard segments in butylene terephthalate-ε-caprolactone (PBT-PCL) copolyesters were carefully investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction. Every copolyesters exhibits only one transition temperature Tg. The uncrystallized hard and soft segments form a relatively compatible amorphous phase. For those copolyesters with hard segment content higher than 50%, the hard segments can crystallize, while the soft segments can not. The soft segments confine the crystallization of hard segments. The crystallizability of hard segments increases with increasing hard segment sequence length.