Structural Changes of Melt-quenched Poly(ethylene terephthalate) on Annealing Infrared Spectroscopic Study

Abstract

Structural changes of melt-quenched poly (ethylene terephthalate) (PET) on annealing have been studied mainly with the infrared spectroscopic method. The structural features of annealed PET are characterized by the trans fraction in the ethylene part and the planarity of the terephthaloyl part. These features are successfully explained from the consideration that the resulting structure is formed through the solid-solid transition from our previously proposed structure for melt-quenched PET. Crystallization at lower temperature (below 200°C) is induced by the local conformational changes of distorted chains and ordering to the more perfectprystalline state at highertemperature (above 200°C) takes place through sliding diffusion of chains which results in the increase of long period. The two-step crystallization can not be explained in terms in the random coil structure for melt-quenched PET.