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Thermal and electrical conductivity of carbon nanotube materials.

机译：碳纳米管材料的导热性和导电性。

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摘要

The thermal conductivity (kappa) and electrical conductivity (sigma) of three types of carbon nanotube (CNT) materials, CNT/polymer composites, CNT films, and CNT arrays, were studied over temperature ranges spanning from 2 to 390 K.;Covalent CNT-matrix bonding was explored to reduce RK. Composites with the highest degree of direct SWCNT-epoxy bonding, achieved by reaction of charged SWCNTs with epoxy, showed small kappa-enhancements (2 to 3%), limited by low loading (0.13 mass%). The estimated reduction in RK was somewhat larger than predicted and suggests that significant enhancements could be achieved in a system with higher loading. The composites had large sigma-enhancements and CNT-epoxy bonding did not necessarily reduce sigma. As a function of temperature and voltage, sigma was consistent with the model of fluctuation-assisted tunneling.;A novel approach was developed to produce SWCNT films by filtration and transfer them to arbitrary substrates. The sheet resistances (e.g. , 400 O/□ at 85% transmittance) were competitive with films produced by more cumbersome procedures, and varied with HNO3 treatments. Thermal characterization suggests that these materials have low kappa.;For tall (2 to 6 mm) MWCNT arrays, the measured kappa (1.2 to 0.5 W m-1 K-1) and sigma (14 to 7 S cm-1 ) values at room temperature decreased with array height. These values are higher than CNT/polymer composites but, even considering the low fill fraction ( 3%), suggest relatively modest kappaCNT.;For composites of multi- or single-walled CNTs (MWCNTs or SWCNTs) in epoxy, small kappa-enhancements (a few percent) were observed at room temperature. The enhancements decreased with decreasing temperature, and at low temperature (2 to 10 K) kappa can be less than that of the neat epoxy. This was attributed to interfacial thermal resistance (RK). For MWCNT/epoxy with a range of loading, RK was found to increase with decreasing temperature. Larger kappa-enhancements (50% at 300 K) were observed for 1 mass% SWCNT/polystyrene and a similar trend of decreasing kappa-enhancement was evident from 360 to 140 K.;The overall results indicate that high kappa is difficult to achieve in CNT materials. The materials studied here suggest directions for design of electrically conductive thermal insulators.
机译：在2至390 K的温度范围内研究了三种类型的碳纳米管（CNT）材料，CNT /聚合物复合材料，CNT膜和CNT阵列的导热率（kappa）和电导率（sigma）。 -矩阵键被探索以减少RK。通过带电SWCNT与环氧树脂反应获得的具有最高SWCNT-环氧直接键合度的复合材料，其Kappa增强小（2-3％），受低负荷（0.13质量％）的限制。 RK的估计减少量比预期的要大一些，这表明在负载较高的系统中可以实现显着的增强。复合材料具有较大的sigma增强作用，而CNT-环氧键合并不一定会降低sigma。作为温度和电压的函数，sigma与波动辅助隧穿模型相一致。；开发了一种通过过滤生产SWCNT膜并将其转移到任意衬底上的新方法。薄层电阻（例如，在85％透射率下为400O /□）与通过更繁琐的程序生产的膜竞争，并且随HNO 3处理而变化。热特性表明这些材料的kappa值较低;对于较高的（2至6 mm）MWCNT阵列，测得的kappa（1.2至0.5 W m-1 K-1）和sigma（14至7 S cm-1）值为室温随阵列高度降低。这些值高于CNT /聚合物复合材料，但即使考虑到较低的填充率（<3％），也建议使用相对适中的kappaCNT。在室温下观察到增强（百分之几）。增强作用随温度降低而降低，在低温（2至10 K）下，κ值可小于纯环氧树脂。这归因于界面热阻（RK）。对于具有一定负载范围的MWCNT /环氧树脂，发现RK随着温度降低而增加。 1质量％SWCNT /聚苯乙烯的Kappa增强较大（在300 K时为50％），并且从360 K到140 K都有明显的Kappa增强下降趋势;总体结果表明，很难实现高Kappa的增强。碳纳米管材料。此处研究的材料为导电绝热材料的设计提供了指导。

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  • 作者

    Jakubinek, Michael B.;

  • 作者单位

    Dalhousie University (Canada).;

  • 授予单位 Dalhousie University (Canada).;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 191 p.
  • 总页数 191
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 非洲史;
  • 关键词

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