Blends of a thermotropic liquid-crystalline polymer and a poly(butylene terephthalate)/organoclay nanocomposite

Abstract

Blends were synthesized via the melt blending of a thermotropic liquid-crystalline polymer (TLCP) and a poly(butylene terephthalate) (PBT) hybrid containing 2 wt % organoclay. A TLCP was also synthesized with side groups based on a nematic liquid-crystalline phase. The blends of TLCPs with PBT hybrids were melt-spun with different concentrations of the liquid-crystalline polymer and different draw ratios (DRs) to produce monofilaments. Regardless of the TLCP concentration in the hybrids, transmission electron microscopy photographs proved that the clay layers of the organoclay were intercalated and partially exfoliated in the PBT matrix. At DR = 1, the maximum enhancement in the ultimate tensile strength was observed for blends containing 8% TLCP, and the tensile strength decreased with further increases in the TLCP concentration. The initial modulus monotonically increased with increasing TLCP concentration. When DR increased from 1 to 44, the increased stretching caused the tensile property to decrease significantly, debonding to occur, and voids to form. These trends with increasing DR were observed in all the systems. (C) 2004 Wiley Periodicals, Inc.