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为了进一步研究聚合物基复合材料的拉伸效应,采用简单的物理混合法制备了Ni/PVDF复合薄膜并在120℃下进行拉伸改性研究。结果表明:镍含量远低于渗流阈值的样品,通过拉伸实现了与渗流效应类似的介电常数剧增的拉伸渗流效应;在伸长倍数为2.3时介电常数急剧增大,最大增幅17倍(12→220),同时电导率也增大了4~5个数量级,薄膜有绝缘体向导体转变的趋势。介电常数随拉伸倍数增加而大幅增加,是因为复合薄膜中的镍颗粒在外力拉伸作用下,其分布、微观结构逐步发生变化,以致形成了杆状镍颗粒群和微平行电容器结构等导电网络,发生拉伸渗流效应;同时,电导率的大幅增加也符合渗流理论的特征。
In order to further study the stretching effect of the polymer matrix composites, a Ni / PVDF composite film was prepared by a simple physical mixing method and the tensile modification was carried out at 120 ℃. The results show that the tensile permittivity of the sample with the nickel content far lower than the percolation threshold value is greatly increased by stretching, and the permittivity increases sharply when the extension factor is 2.3, and the maximum increase 17 times (12 → 220), at the same time the conductivity also increased by 4 to 5 orders of magnitude, the insulator has a thin film conductor to the trend of change. The dielectric constant increases greatly with the increase of draw ratio because the distribution and microstructure of nickel particles in the composite film change gradually under the action of external force, which results in the formation of rod-shaped nickel particles and micro-parallel capacitor structure Conductive network, the tensile seepage effect occurs; the same time, a substantial increase in conductivity is also in line with the theory of seepage characteristics.