Microstructural Modifications in Uniaxially Hot-Drawn Polycyclohexylene Terephthalate Films

摘要

Semi-aromatic thermoplastic polycyclohexylene terephthalate (PCT), initially wholly amorphous, was uniaxially drawn to study microstructural modifications as the appearance of the strain-induced (S.I.) crystalline phase. Polyethylene terephthalate (PET) and poly(ethylene glycol-co-cyclohexane-l,4-dimethanol terephthalate) (PETG) are considered as reference materials in this work. In polycyclohexylene terephthalate (PCT) the presence of a saturated ring (which is not quite as rigid as the aromatic ring) modifies the characteristics of both thermal and S.I. crystallization. Samples with various draw ratios (drawing of PCT films is performed at T > T_g) were analyzed by Modulated Differential Scanning Calorimetry, wide angle X-ray scattering, and birefringence measurements. In drawn PCT films, an S.I. crystalline phase appears continuously with the draw ratio and reaches 35%. For this polymer and for the highest draw ratio, the "true" amorphous fraction practically disappears. The material is composed only of the S.I. crystalline phase and the "rigid" amorphous phase.