论文标题
聚合物复合材料中电和热渗透的统一建模和实验实现
Unified Modeling and Experimental Realization of Electrical and Thermal Percolation in Polymer Composites
论文作者
论文摘要
由于电荷和热载体在填充颗粒的纳米级连接处的复杂贡献，聚合物复合材料中电和热传导之间的相关性变得模糊。关于聚合物复合材料中缺乏或存在热渗透的报道相互矛盾，使其成为数十年来引起极大争议的主题。在这里，我们开发了一个广义的渗滤框架，该框架描述了在较宽的填充与矩阵电导率比（y_f/y_m）范围内的电导率和热导率，覆盖了20个数量级。我们的统一理论提供了典型的y_f/y_m> = 10^10作为绝缘体 - 导电器渗透的真实分类，并具有标准幂律行为，并具有10^2 <= y_f/y_m <= 10^4的热导率，为较差的良好的导体渗透，由两个通用临界值crivident crigical Privestentent代表。通过在精心设计的制造方法下，作为模型聚合物基质作为模型聚合物基质，对我们理论框架的通用和统一特征进行了实验验证。我们研究了我们制造的复合材料中电导率和热导率的演变，其不同负载水平高达5 vol％。值得注意的是，我们发现以0.02 vol％为0.02的超低电渗透阈值，在1.5 vol％下的记录 - 低热渗透阈值。我们还将理论模型应用于文献中报道的23个独立的实验和数值数据集，包括350多个数据点，对具有不同微观细节的系统，并表明所有这些都崩溃了我们所提出的通用缩放函数，这仅取决于维度。
Correlations between electrical and thermal conduction in polymer composites are blurred due to the complex contribution of charge and heat carriers at the nanoscale junctions of filler particles. Conflicting reports on the lack or existence of thermal percolation in polymer composites have made it the subject of great controversy for decades. Here, we develop a generalized percolation framework that describes both electrical and thermal conductivity within a remarkably wide range of filler-to-matrix conductivity ratios (Y_f/Y_m), covering 20 orders of magnitude. Our unified theory provides a genuine classification of electrical conductivity with typical Y_f/Y_m >= 10^10 as insulator-conductor percolation with the standard power-law behavior, and of thermal conductivity with 10^2<= Y_f/Y_m <= 10^4 as poor-good conductor percolation characterized by two universal critical exponents. Experimental verification of the universal and unified features of our theoretical framework is conducted by constructing a 3D segregated and well-extended network of multi-walled carbon nanotubes in polypropylene as a model polymer matrix under a carefully designed fabrication method. We study the evolution of the electrical and thermal conductivity in our fabricated composites at different loading levels up to 5 vol%. Significantly, we find an ultralow electrical percolation threshold at 0.02 vol% and a record-low thermal percolation threshold at 1.5 vol%. We also apply our theoretical model to a number of 23 independent experimental and numerical datasets reported in the literature, including more than 350 data points, for systems with different microscopic details, and show that all collapse onto our proposed universal scaling function, which depends only on dimensionality.
