Crystallization Behaviors of Poly(ethylene 2,6-naphthalate) in the Presence of Liquid Crystalline Polymer

The crystallization behaviors and morphology of poly(ethylene 2,6-naphthalate) (PEN) in the presence of liquid crystalline polymer (LCP) Vectra RD501 have been studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), atomic force microscopy (AFM), and wide-angle X-ray diffraction (WAXD). It was found that the LCP in PEN/LCP blends accelerates the crystallization rate of PEN at both higher and low crystallization temperatures, which indicates that LCP acts as both nucleating agent and nucleation promoter for PEN crystallization. The crystallization of PEN was effectively improved with increasing LCP content up to 1 wt %, and then tended to level off with increasing LCP. The Avrami exponent n changed from 2.0−2.7 for pure PEN to <2 for PEN in the presence of LCP, which indicated that the nucleation mechanism of PEN crystallization was changed. The size of the PEN spherulitic crystals became smaller in the presence of LCP, but WAXD has shown that there is no change in the crystal modifications of PEN.