| Abstract: | Polyethylene terephthalate (PET) oligomer samples crystallized and annealed at high pressure were investigated with differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that better crystals were obtained through high-pressure crystallization from the melt than annealing under the same conditions. The difference of the effects of crystallization and annealing on the morphology of crystals reduced with the increase of crystallization time. The melting temperature was determined by the lamellar thickness when it was shorter than the length of the molecular chains, while the main factor governing the melting temperature changed from lamellar thickness to density of chain-end defects when the lamellar thickness was much longer than the molecular length. PET oligomer extended-chain crystals with thickness up 100 μm were obtained. |
