CRYSTALLIZATION OF POLY(ETHYLENE-TEREPHTHALATE) (PET) FROM THE ORIENTED MESOMORPHIC FORM

Yarns of different inherent viscosities, in the range 0.6-1.1 dL/g, sp un in industrial plants, and drawn at room temperature to obtain mesom orphic samples, have been characterized. The evolution from the mesomo rphic form toward the triclinic crystalline form has also been studied by combined differential scanning calorimetry (DSC), dynamic mechanic al analyses (DMA), and accurate wide angle X-ray diffraction experimen ts. The DMA analysis of the mesomorphic samples allows better resoluti on of the glass transition and crystallization phenomena, which are su perimposed in the DSC scans. The degree of molecular orientation in th e mesomorphic samples, and the temperature of crystallization from the mesomorphic form (60-80-degrees-C), are essentially independent of th e polymer molar mass. (C) 1994 John Wiley & Sons, Inc.