An exfoliation of organoclay in thermotropic liquid crystalline polyester nanocomposites

Abstract

A thermotropic liquid crystalline polyester (TLCP) with an alkoxy side-group was synthesized from 2-ethoxyhydroquinone and 2-bromoterephthalic acid. Nanocomposites of TLCP with Cloisite 25A (C25A) as an organoclay were prepared by the melting intercalation method above the melt transition temperature (T-m) of the TLCP. Liquid crystallinity, morphology, and thermo-mechanical behaviors were examined with increasing organoclay content from 0 to 6%. Liquid crystallinity of the C25A/TLCP hybrids was observed when organoclay content was up to 6%. Regardless of the clay content in the hybrids, the C25A in TLCP was highly dispersed in a nanometer scale. The hybrids (0-6% C25A/TLCP) were processed for fiber spinning to examine their tensile properties. Ultimate strength and initial modulus of the TLCP hybrids increased with increasing clay content and the maximum values of the mechanical properties were obtained from the hybrid containing 6% of the organoclay. Thermal, morphological and mechanical properties of the nanocomposites were examined by differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), polarized optical microscope, electron microscopes (SEM and TEM), and capillary rheometer. (C) 2002 Elsevier Science Ltd. All rights reserved.