Morphology of high-pressure crystallized poly(ethylene 2,6-naphthalate)

The high-pressure crystallized poly(ethylene 2,6-naphthalate) (PEN) samples were investigated using wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). DSC results showed that the melting temperature of high-pressure crystallized PEN samples was up to 603 K, which is much higher than the equilibrium melting point of PEN suggested by Buchner et al. and near to the value estimated by Cheng et al. The striations in the morphology of PEN extended-chain crystals with thickness of about 1.5 μm were observed with SEM. Some characteristic spherulitic forms obtained at high pressure are also presented.