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SynopsisMorphology and tensile behavior of wet-spun fibers of poly-p-phenylene benzobisthiazole have been investigated. The as-spun fibers contain a large number of voids, which result in void-localized tensile failure. The stress-strain behavior is elastic-plastic with strain hardening. This behavior is shown to be the result of residual stresses which arise during the wet-spinning process.

A novel glycidyl-terminated benzaldehyde azine was synthesized and subsequently cured with an aromatic diamine. The resulting liquid-crystalline network was characterized by means of optical microscopy, X-ray analysis and dynamic-mechanical analysis. The influence of the curing temperature on the nematic textures is pointed out. The curing reaction was followed by means of differential scanning calorimetry and dielectric analysis.

Toughening epoxy resins can be achieved by blending a low percentage of Liquid Crystalline Polymer with the thermoset. The processing technique consists of the spinning of blends of a thermoplastic (Ardel) with the LCP (PET/PHB60). The bundled filaments are subsequently dissolved in the uncured epoxy resin (Epon 825). After curing, the LCP phase separates from the matrix in the form of microfibers with a very high aspect ratio, which act as crack stoppers and improve fracture toughness of the material