柔性导电热塑性聚氨酯基取向多孔复合材料的制备及性能研究

发布时间：2018-06-15 04:40

本文选题：热塑性聚氨酯 + 碳纳米管　；参考：《郑州大学》2017年硕士论文

【摘要】：导电高分子复合材料(Conductive polymer composites,CPCs)是将一种或多种导电填料加入高分子基体中复合制备而成的一类具有导电功能的复合材料。由于其具有成本低,易加工和性能易调控等优点,受到人们的广泛关注。CPCs在受到外界刺激(如应变、温度、有机气体等)时电阻会发生规律的变化,因此其在柔性传感器领域具有极其广阔的应用前景。传统方法制备的CPCs基应变传感器存在输出信号不稳定,应变范围小等缺点,限制了其实际应用。随着研究的深入,人们已制备出了具有较大应变测试范围的CPCs多孔材料,但是该类材料的力学性能较弱,且应变响应行为的稳定性和可回复性较差。因此,通过对多孔材料微观结构的调控,制备出具有较大压缩应变、较高的力学性能、良好的稳定性和可回复性的多孔CPCs材料具有重要的研究意义。本文以热塑性聚氨酯(TPU)为基体,以碳纳米管(CNTs)为导电填料,采用单向冷冻与冷冻干燥相结合的方法,制备出质轻的柔性CNTs/TPU取向多孔材料。对该材料的结构与性能进行了研究,主要成果如下:1.首次采用单向冷冻-冷冻干燥技术成功制备了具有取向泡孔结构的CNTs/TPU导电复合材料。孔径约为10μm,CNTs均匀的分布在TPU基体中。由于CNTs分散均匀以及CNTs和TPU之间结合良好,CNTs/TPU取向多孔材料具有超低逾渗值(体积分数为0.0023%)。由于多孔结构的存在,取向多孔材料的密度低至0.13 g·cm-3。与无规多孔CPCs材料相比,其在取向方向上的力学性能得到了显著的提高。2.研究了CNTs/TPU取向多孔材料的压敏特性。在压缩过程中复合材料的电阻值随压缩应变的增大呈现出单调下降的趋势,在回复过程中电阻上升并且能够较好的回复到初始值。这是由于压缩过程中泡孔壁相互接触形成更多的导电通路,使得材料的电阻值下降;而在回复过程中因受压而接触的泡孔壁又再次分离,导致导电通路的减少而使电阻值上升。复合材料在压缩应变下在较大的压缩应变范围(0-77%)内显示出良好的线性行为。基于构筑的取向多孔结构,该材料具有良好的结构完整性和优异的力学性能,在2000个循环压缩之后依然保持着良好的稳定性和可回复性,表明该材料具有良好的耐久性,适合长期使用。另外,材料在多种不同的人体运动下模式下均显示出较快的响应速率以及良好的稳定性,显示了其在人体运动检测领域的潜在应用价值。3.研究了CNTs/TPU取向多孔材料的弯曲敏感性能以及拉伸敏感性能。在弯曲过程中材料的电阻值呈现出单调下降的趋势,回复过程电阻上升,与压缩过程不同的是,其电阻不能回复到初始值,这是由于弯曲过程中部分导电网络受到了永久性破坏,导致材料的阻值上升。多循环测试也显示出较差的稳定性。考察了预处理对材料弯曲敏感性能稳定性的影响,结果表明对复合材料进行20个循环的预处理后直接进行循环弯曲测试,其对稳定性提升作用不明显;而在弯曲处理后给予试样24 h的回复时间,发现当预处理应变大于循环弯曲的应变时复合材料具有良好的稳定性和可回复性。另外,在拉伸应变测试时发现CNTs/TPU取向多孔材料的断裂伸长率高达170%,远远超越了文献报道的大多数多孔材料。在拉伸的过程中复合材料的电阻上升,回复时电阻下降。由于部分泡孔壁的永久性破坏导致电阻不能回复到初始值。循环拉伸结果显示出较差的稳定性。基于弯曲敏感测试预处理的实验基础,对复合材料进行20个循环的预拉伸处理后恢复24 h,材料的拉伸敏感性能的稳定性和可回复性性能得到了显著的提高。
[Abstract]:Conductive polymer composites (CPCs) is a kind of composite material with conductive function prepared by adding one or more conductive fillers into the polymer matrix. Because of its advantages of low cost, easy processing and easy to control performance, the.CPCs is stimulated by the outside world. Such as strain, temperature, organic gas and so on, the resistance will change regularly, so it has an extremely broad application prospect in the field of flexible sensor. The CPCs based strain sensor prepared by traditional methods has the disadvantages of unstable output signal and small strain range, which limits its practical application. With the further research, people have prepared it. CPCs porous materials with large strain testing range, but the mechanical properties of these materials are weak, and the stability and recoverability of the strain response are poor. Therefore, through the regulation of the microstructure of the porous materials, the porous CPCs has large compressive strain, high mechanical properties, good stability and recoverability. The material has important research significance. In this paper, the flexible CNTs/TPU oriented porous materials with light quality were prepared by the method of Unidirectional Freezing and freeze drying, using thermoplastic polyurethane (TPU) as the matrix and carbon nanotube (CNTs) as the conductive filler. The structure and properties of the material were studied. The main achievements are as follows: 1. the first use of single. A CNTs/TPU conductive composite with an orientated bubble structure was prepared successfully by cryo freeze drying. The pore size of the composite was about 10 u m and CNTs was evenly distributed in the TPU matrix. Because of the uniform dispersion of CNTs and the good bonding between CNTs and TPU, the CNTs/TPU oriented porous material has a ultra low percolation value (volume fraction of 0.0023%). The porous structure is due to the porous structure. When the density of the porous material is as low as 0.13 G. Cm-3., compared with the random porous CPCs material, the mechanical properties in the orientation direction are greatly improved by.2., and the pressure sensitivity of the CNTs/TPU oriented porous material is studied. The resistance value of the composite material decreases with the increase of compressive strain during the compression process. In the process of recovery, the resistance rises and can recover to the initial value. This is due to the interaction of the bubble hole wall in the compression process to form more conductive path and the decrease of the resistance value of the material; and the wall of the bubble hole contacted by pressure in the recovery process is again separated, and the conductivity of the conductive path is reduced and the resistance value is increased. The material shows good linear behavior under the larger compression strain range (0-77%) under the compression strain. Based on the constructed orientation porous structure, the material has good structural integrity and excellent mechanical properties. After 2000 cyclic compression, the material still maintains good stability and recoverability, indicating that the material is good. The durability is suitable for long term use. In addition, the material shows a fast response rate and good stability under various human motion patterns. The potential application value of the material in the field of human motion detection.3. has been studied for flexural sensitivity and tensile sensitivity of CNTs/TPU oriented porous materials. The resistance of materials in the process shows a monotonous decline trend and the resistance of the recovery process rises. Unlike the compression process, the resistance can not revert to the initial value. This is due to the permanent damage of the conductive network in the process of bending, which leads to the increase of the material resistance. The multi cycle test also shows the poor stability. Inspection also shows the poor stability. The effect of pretreatment on the stability of the material's flexural sensitivity shows that the composite material is subjected to 20 cycles of pretreatment to test the cyclic bending directly after 20 cycles, and the effect on the stability is not obvious. The recovery time of the 24 h is given after the bending treatment, and it is found that the composite material is more than the strain of the pre treated strain when the strain is larger than the cyclic strain. The material has good stability and recoverability. In addition, the elongation at break of the CNTs/TPU oriented porous material was found to be up to 170% at the tensile strain test. It was far beyond most of the porous material reported in the literature. The resistance of the composite material increased and the electrical resistance decreased during the stretching process. The permanent damage to the wall of some bubbles was destroyed. The resistance can not be recovered to the initial value. The cyclic tensile results show a poor stability. Based on the experimental basis of the flexural sensitivity test preconditioning, the composite material is pretreated with 20 cycles to recover 24 h, and the stability and recoverability of the tensile sensitivity of the material have been greatly improved.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332

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