Abstract Carbon nanotubes/epoxy composites are increasingly employed in several industrial fields, because of the enhanced material properties provided by the nanofillers. In particular, the thermal conductivity of these nanocomposites is determined by heat transfer mechanisms occurring over multiple scales, thus causing a complex relation between effective response and microscopic characteristics of the material. Here, the thermal properties of epoxy composites reinforced by carbon nanotubes are investigated using atomistic simulations. For a better understanding of how the effective thermal conductivity arises from the characteristics of the composite at the nanoscale, the thermal properties of its constituents are studied separately according to different geometrical, physical and chemical characteristics. The thermal conductivity of carbon nanotubes and epoxy resin alone is first investigated by molecular dynamics; then, the Kapitza resistance at the nanotube–nanotube and nanotube–epoxy interfaces is studied as well. The effective thermal conductivity of the carbon nanotubes/epoxy composite is finally computed and the observed behavior interpreted on the basis of the properties of the nanofillers, matrix and interfaces alone. Results – verified against effective medium theory predictions – show that, for the considered configurations, the effective thermal conductivity of the nanocomposite increases with the nanotube length and volume fraction, with the curing degree of the epoxy and system temperature. In perspective, the presented approach could be employed to investigate other constitutive materials or properties of nanocomposites.

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通过原子模拟研究碳纳米管/环氧树脂复合材料的纳米级热性能

摘要碳纳米管/环氧树脂复合材料越来越多地用于几个工业领域，因为纳米填料提供了增强的材料特性。特别是，这些纳米复合材料的热导率由发生在多个尺度上的传热机制决定，从而导致有效响应与材料微观特性之间的复杂关系。在这里，使用原子模拟研究了由碳纳米管增强的环氧树脂复合材料的热性能。为了更好地理解复合材料在纳米尺度上的特性如何产生有效热导率，根据不同的几何、物理和化学特性分别研究其成分的热性能。首先通过分子动力学研究碳纳米管和环氧树脂单独的热导率；然后，还研究了纳米管-纳米管和纳米管-环氧树脂界面处的 Kapitza 电阻。最后计算碳纳米管/环氧树脂复合材料的有效热导率，并根据纳米填料、基体和界面的特性解释观察到的行为。结果——根据有效介质理论预测进行了验证——表明，对于所考虑的配置，纳米复合材料的有效热导率随着纳米管长度和体积分数、环氧树脂的固化程度和系统温度而增加。从长远来看，所提出的方法可用于研究纳米复合材料的其他构成材料或性质。