Development of nano-fibers and the application to apparel science

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This research deals with the mechanical properties of composite materials of polymer and fillers in terms of apparel and clothing science. The composites by admixing common conductive fillers are characterized by a percolation threshold or a critical value at which the conductivity starts to increase as a function of filler contents. Multi-wall carbon nenotubes (MWNTs) and carbon fibers (CF) were uesed as fillers and ultra-high molecular weight polyethylene (UHMWPE) were used as matrix.. The composite materials were prepared by gelation./crystallization from solution.. UHMWPE and MWNT composites were prepared using either decalin or paraffin as solvent. Electrical conductivity measurements were performed for the original and heat-treated composites. The drastic increase in conductivity occurred at low MWNT content for the composite prepared in paraffin, while the conductivity of the composite prepared in decalin increased slightly up to l0wt% MWNT content. Scanning electron microscopy … More observations revealed that the MWNTs within the composite prepared in decalin were covered by UHMWPE, and their average diameters were much greater than those of the original MWNTs, while the average diameter of the MWNTs within the composite prepared in paraffin was similar to the diameter of the original MWNTs. Such different morphology was found to be due to the different crystallization.Some of UHMWPE - carbon filler composites showed a sharp increase in electrical resistivity at elevated temperature close to the polymer melting point, which is known as the positive temperature coefficient (PTC) effect. A simple resistor-capacitor circuit model id proposed to explore the alternating current (AC) conductivity and dielectric permittivity behavior of UHMWPE-CF composites. The composites are considered as a system composed of random arrays of closely spaced conductors dispersed in an insulating UHMWPE matrix and broad frequency measurements are carried out to probe the conducting path and the space gaps to show the experimental evidence for explaining PTC mechanism. Less