The nonlinear response in high-density polyethylene/graphite nanosheets conducting composites under increasing applied voltage is investigated. Under sufficient applied constant voltage, the resistance increases initially due to Joule heating effect and then eventually reaches a steady value with a characteristic thermal relaxation time τ h , which decreases as the applied field increases. The switch value, namely the ratio of the resistance under steady condition to the resistance of sample in linear regime, gradually increases with the increasing applied field. The threshold voltage (V 0) at which the resistance start to increase with time scales with linear regime resistance (R 0) of the sample as V0 ~ Rx0 , V_{0} sim R^{x}_{0} , with the exponent x = 0.78 ± 0.05. All the curves of R/R 0 vs. V/V 0 collapse to a similar curve with the function R/R 0 = 1 + α(V/V 0) θ . The results reveal that the threshold voltage value decreases with increasing graphite nanosheets content in the composites.
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机译：研究了在高施加电压下导电复合材料的高密度聚乙烯/石墨纳米片的非线性响应。在足够的施加恒定电压下，电阻最初由于焦耳热效应而增加，然后最终达到具有特征性热弛豫时间τ h 的稳定值，该值随施加电场的增加而减小。开关值，即稳态下的电阻与线性状态下样品的电阻之比，随着施加场的增加而逐渐增加。阈值电压（V 0 ）处的电阻开始随时间尺度而增加，并且样品的线性态电阻（R 0 ）为V 0 〜R x 0 ，V_ {0} sim R ^ {x} _ {0}，指数x = 0.78±0.05。 R / R 0 相对于V / V 0 的所有曲线都折叠为函数R / R 0 = 1 +的相似曲线α（V / V 0 ）θ。结果表明，阈值电压值随着复合材料中石墨纳米片含量的增加而降低。
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