Poly -liquid-crystalline copolymer blends

Meng, Y. Z., Tjog, S. C., and Hay, A. S. 1998. Morphology, rheological and thermal properties of the melt blends of poly (phthalazinone ether ketone sulfone) with liquid crystalline copolymer. Polymer 39(10) 1845-1850. 

PEEK showed extreme thermal stability, but when blended with a liquid crystalline poly(hydroxybenzoic/naphthoic acid) copolymer, LCP, there is a measurable reduction in this property [Mehta and Isayev, 1991]. 

One of the basic problems confronting molecular composites is the difficulty of finding miscible combinations of rigid rod polymers with flexible chain polymers. Poly(p-phenylene benzobisthiazole)/poly(-2,5(6)-benzimidazole block copolymers have been reported by Tsai et al. [1985] and are noted to exhibit better processability and mechanical properties than the simple blends of the block copolymer constituents. Chang and Lee [1993] prepared poly(p-benzamide)/Pl block copolymers and reported on the liquid crystalline behavior. Such approaches would appear to have future implications. As an example PA e.g., PA-66) block copolymers with rigid rod polyamides could be prepared and used in blends with PA-66 to yield the desired molecular composite. 

Gopakumar et al. [10] reported the in situ compatibilization of poly(phenylene sulfide) (PPS)/wholly aromatic thermotropic liquid crystalline polymer (TLCP) Vectra A950 blends by reactive extrusion. The authors prepared the in situ compatibilized PPS/TLCP blends in a twin-screw extruder by reactive blending of PPS and TLCP in the presence of dicarboxyl-terminated poly(phenylene sulfide) (DCTPPS). Block copolymer was formed during reactive blending, by transesterification reaction between carboxyl... 

In this and the following two sections we consider the data for a PLC and for different blends of that PLC with isotactic polypropylene (PP). The PLC used in this study was liquid crystalline copolyester PET/0.6PHB, where PET = poly (ethylene terephthalate), PHB = p-hydroxybenzoic acid and 0.6 is the mole fraction of PHB in the copolymer, manufactured by Unitika Ltd, Kyoto, Japan. The content of the PLC in the blends with PP was varied from 0 to 20 wt%. The samples were prepared by injection molding. PP, resin VB65 llB, was supplied by Neste OY, Finland. 

Electrical properties have been reported on numerous carbon fiber-reinforced polymers, including carbon nanoflber-modified thermotropic liquid crystalline polymers [53], low-density polyethylene [54], ethylene vinyl acetate [55], wire coating varnishes [56], polydimethyl siloxane polypyrrole composites [50], polyacrylonitrile [59], polycarbonate [58], polyacrylonitrile-polycarbonate composites [58], modified chrome polymers [59], lithium trifluoromethane sulfonamide-doped polystyrene-block copolymer [60], boron-containing polyvinyl alcohols [71], lanthanum tetrafluoride complexed ethylene oxide [151, 72, 73], polycarbonate-acrylonitrile diene [44], polyethylene deoxythiophe-nel, blends of polystyrene sulfonate, polyvinyl chloride and polyethylene oxide [43], poly-pyrrole [61], polypyrrole-polypropylene-montmorillonite composites [62], polydimethyl siloxane-polypyrrole composites [63], polyaniline [46], epoxy resin-polyaniline dodecyl benzene sulfonic acid blends [64], and polyaniline-polyamide 6 composites [49]. 

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