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首页> 外文学位 >Deformation dependent electrical resistance of MWCNT layer and MWCNT/PEO composite films.
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Deformation dependent electrical resistance of MWCNT layer and MWCNT/PEO composite films.

机译：MWCNT层和MWCNT / PEO复合膜的变形依赖电阻。

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It has been well documented that the electrical properties of a carbon nanotube (CNT) can be either metallic or semiconducting depending upon the tube's chirality. Theoretical aspects of the unique electrical properties of CNTs are reviewed. Based upon the fundamental understanding of this special feature, the deformation-dependent electrical resistance of multiwalled carbon nanotube (MWCNT) layer and MWCNT/polyethylene oxide (PEO) composite in the macroscopic scale are investigated considering both experimental and theoretical aspects. In the first set of experiments, a MWCNT layer was grown by plasma enhanced chemical vapor deposition (PECVD) process on a surface of copper substrate and a copper probe was applied to this surface inducing compressive deformation onto the MWCNT layer. It was found that the electrical resistance of the MWCNT layer under compression was reduced by 80 percent. The possible mechanisms for electrical resistance reduction were analyzed and suggested. Also, the MWCNT-enhanced surface showed a finite slope of electrical resistance as a function of contact force, thereby making possible the use of this arrangement as a small-scale force or pressure sensor. However, there is limitation on the direct use of MWCNT grown directly onto copper substrates for real applications due to the easy separation of the MWCNTs from the copper surface and the low yield of MWCNTs by the given metal deposition and PECVD system.; The processing method developed for the second set of experiments uses intentional coagulation of dispersed MWCNT in polymer solution. This process is simple and effective to fabricate MWCNT-filled polymer films. MWCNT/PEO composite was selected after comparative resistivity measurement and microstructure analysis. The percolation threshold of MWCNT/PEO was determined experimentally to be between 0.14 to 0.28 vol% of MWCNT. Films having MWCNT content above the percolation threshold were conductive and exhibited repeatable values of electrical conductivity. Unique and repeatable relationships of resistance versus strain were obtained for multiple samples with different volume fractions of MWCNT. The overall pattern of electrical resistance change versus strain for the samples of each volume fraction of MWCNT consists of linear and non-linear regions. A model to describe the combination of linear and non-linear modes of electrical resistance change as a function of strain is suggested. The unique characteristics in electrical resistance change for different volume fractions implies that nanotube-based composites can be used as tunable strain sensors for application into embedded sensor systems in structures.
机译：已经充分证明，取决于管的手性，碳纳米管（CNT）的电特性可以是金属的也可以是半导体的。综述了碳纳米管独特电性能的理论方面。基于对这一特殊功能的基本理解，从实验和理论两个方面研究了多壁碳纳米管（MWCNT）层和MWCNT /聚环氧乙烷（PEO）复合材料的变形相关电阻。在第一组实验中，通过等离子体增强化学气相沉积（PECVD）工艺在铜基板的表面上生长了MWCNT层，并在该表面上施加了铜探针，从而在MWCNT层上产生了压缩变形。发现在压缩下的MWCNT层的电阻降低了80％。分析并提出了降低电阻的可能机制。而且，MWCNT增强的表面显示出有限的电阻斜率作为接触力的函数，从而使得可以将该装置用作小规模的力或压力传感器。然而，由于在给定的金属沉积和PECVD系统中容易将MWCNT从铜表面分离并且MWCNT的低产率，因此直接生长在铜基板上的直接生长在实际应用中的MWCNT受到限制。为第二组实验开发的处理方法使用聚合物溶液中分散的MWCNT的有意凝结。该方法简单且有效地制备了MWCNT填充的聚合物膜。经过比较电阻率测量和微观结构分析，选择了MWCNT / PEO复合材料。通过实验确定MWCNT / PEO的渗透阈值为MWCNT的0.14至0.28vol％。 MWCNT含量高于渗透阈值的薄膜具有导电性，并显示出可重复的电导率值。对于具有不同体积分数的MWCNT的多个样品，获得了电阻与应变的独特且可重复的关系。 MWCNT的每个体积分数的样品的电阻变化与应变的整体模式包括线性和非线性区域。建议使用一个模型来描述电阻变化的线性和非线性模式的组合作为应变的函数。不同体积分数下电阻变化的独特特性意味着基于纳米管的复合材料可用作可调应变传感器，可应用于结构中的嵌入式传感器系统。

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