Development of nano-fibers and the application to apparel science

本研究从服装科学的角度探讨高分子与填料复合材料的力学性能。混合普通导电填料的复合材料的特点是有一个渗透阈值或临界值，在这个临界值上，电导率开始随着填料含量的增加而增加。以多壁碳纳米管（MWNTs）和碳纤维（CF）为填料，以超高分子量聚乙烯（UHMWPE）为基体。采用凝胶法制备复合材料。/从溶液中结晶…以十氢化萘或石蜡为溶剂制备了超高分子量聚乙烯和MWNT复合材料。对原始和热处理复合材料进行了电导率测量。在石蜡中制备的复合材料的电导率在低MWNT含量时急剧增加，而在十萘中制备的复合材料的电导率在MWNT含量为低wt%时略有增加。扫描电镜观察发现，在十氢化萘中制备的复合材料内部的MWNTs被超高分子量聚乙烯覆盖，其平均直径远大于原始MWNTs，而在石蜡中制备的复合材料内部的MWNTs的平均直径与原始MWNTs的直径相似。这种不同的形貌是由于结晶不同造成的。在接近聚合物熔点的高温下，某些超高分子量聚乙烯-碳填料复合材料的电阻率急剧增加，这被称为正温度系数（PTC）效应。提出了一种简单的电阻-电容电路模型，用于研究UHMWPE-CF复合材料的交流电导率和介电常数行为。将该复合材料视为分散在绝缘的超高分子量聚乙烯（UHMWPE）基体中的紧密间隔导体的随机阵列组成的系统，并进行了宽频测量来探测导电路径和空间间隙，以提供解释PTC机制的实验证据。少

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