Morphology control and mechanical properties of liquid crystalline polymer-polyamide composite fibers

In this paper, we investigate the relationships between the viscosity ratio, morphology, and processing temperature of composite fibers comprising liquid crystalline polymer (LCP) and polyamide-66 (PA 66). Furthermore, we examine in details the effect of the LCP concentration on the phase microstructure and the mechanical properties of the composite fibers. The results show that, first, the optimal processing temperature of melt spinning of the composite fibers depends strongly on the viscosity ratio of LCP to PA 66 though the processing temperature range can be determined by the degradation temperature of PA 66 and the melting point of LCP. Secondly, the LCP phase structure/morphology in composite fibers can be controlled by the viscosity ratio of LCP to PA 66. Thirdly, the LCP phase structure/morphology are changed with LCP concentration for a fixed viscosity ratio/processing temperature. With an increase in LCP concentration, the morphology of LCP phase is changed from a fine fibril dispersed phase to a perfectly aligned continuous fiber reinforced phase in a rich LCP composite fiber. Finally, the mechanical properties of LCP composite fibers depend on the LCP phase structure/morphology and LCP concentration. The tensile properties of the composite fibers exhibit the positive synergy in the rich LCP composite fibers.