Frequency and Temperature Dependences of Dielectric Dispersion and Electrical Properties of Polyvinylidene Fluoride/Expanded Graphite Composites
Frequency and Temperature Dependences of Dielectric Dispersion and Electrical Properties of Polyvinylidene Fluoride/Expanded Graphite Composites
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DOI：
10.1155/2010/261748
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发表时间：
2010-01-01
影响因子：
--
通讯作者：
Tjong, Sie Chin
中科院分区：
文献类型：
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作者：
Li, Yu Chao;Li, Robert Kwok Yiu;Tjong, Sie Chin
采用直接熔融共混法将纳米导电填料膨胀石墨（EG）引入到聚偏氟乙烯（PVDF）中。在10（2）~ 10（8）Hz的宽频率范围内研究了所得PVDF/EG复合材料的电导率和介电性能。复合体系的介电色散和电导率表现出很强的频率依赖性，特别是在逾渗阈值（Phi（c）= 6体积%）附近。此外，介电常数随着频率的增加而呈下降趋势，而电导率则呈现相反的趋势。在具有接近Phi（c）的EG含量的复合物中发现大的介电常数。因此，可以用逾渗概念和偏置随机游走方法来描述PVDF/EG体系的载流子输运过程。PVDF/EG复合材料的电导率和介电常数与温度有关。
A conductive nanofiller, expanded graphite (EG), was introduced into polyvinylidene fluoride (PVDF) by direct melt blending process. The electrical conductivity and dielectric properties of resulting PVDF/EG composites were investigated in a wide range of frequencies from 10(2) to 10(8) Hz. The dielectric dispersion and conductivity of the composite system exhibited a strong frequency dependence particularly in the vicinity of percolation threshold (Phi(c) = 6 vol%). Moreover, the dielectric permittivity tended to decrease with increasing frequency while the conductivity displayed a reverse trend. A large permittivity was found in the composite having EG content near Phi(c). Accordingly, percolation concept and biased random walk approach can be used to describe the carrier transport of percolating PVDF/EG system. The conductivity and permittivity of percolating PVDF/EG composites were observed to be temperature dependent.