The effects of ethylene sebacate (ES) content (ranging from O to 15 mol％) on crystallinky

crystallite orientation，crystallite size and long period of annealed (fixed length in 130℃) PET-ES copolyesters fibers were studied by wide-angle X-ray diffraction (WAXD) and smal-langle X-ray scattering (SAXS) methods，and differential scanning calorimetry curve and dyna-mic mechanical behavior were invistigated．The results show a significant decrease of the degree of crystallinity (Xc)，the melting point (Tm)，and the glass transition temperature (Tg) with increasing ES cantent．The crystallite volume increases，but the thickness of crystalline lamellae decreases with rise of the amount of ES in chain molecules．It is shown that the one-dimension two-phase model is not suitable for PET-ES copolymer．And it appears that all the experimental results in the paper can be explain-ed by prevorseks "three-phase model" after some improvemelit．