PTC behavior of polymer composites containing ionomers upon electron beam irradiation

Abstract

We have prepared polymer composites of low-density polyethylene (LDPE) and ionomers (Surlyn 8940) containing polar segments and metal ions by melt blending with carbon black (CB) as a conductive filler. The resistivity and positive temperature coefficient (PTC) of the ionomer/LDPE/CB composites were investigated with respect to the CB content. The ionomer content has an effect on the resistivity and percolation threshold of the polymer composites; the percolation curve exhibits a plateau at low CB content. The PTC intensity of the crosslinked ionomer/LDPE/CB composite decreased slightly at low ionomer content, and increased significantly above a critical concentration of the ionomer. Irradiation-induced crosslinking could increase the PTC intensity and decrease the NTC effect of the polymer composites. The minimum switching current (I trip ) of the polymer composites decreased with temperature; the ratio of I trip for the ionomer/LDPE/CB composite decreased to a greater extent than that of the LDPE/CB composite. The average temperature coefficient of resistance (α T ) for the polymer composites increased in the low-temperature region.

Pressure and temperature induced electrical resistance change in nano-carbon/epoxy composites

“…Some authors [13][14][15][16] reported a slower-than-linear decrease of electrical resistance with increasing temperature in conductive filler based polymer composites. However, other authors observed in nano-carbon/polymer composites an increase of electrical resistance with increasing temperature [17,18]. The causes of this apparent inconsistency deserve a closer look.…”

Positive/Negative Temperature Coefficient Behaviors of Electron Beam-Irradiated Carbon Blacks-Loaded Polyethylene Nanocomposites

“…This is in good agreement with the SEM results (Figure ). The unique structure of the polar additives with oxygen-containing functional groups suggests that they could act as dispersion agents . This might be enabled by the high loading of CBs (65 wt %) compared to the small traces of polar additives (5 wt %) in the present system, which facilitates the formation of the conductive networks.…”

“…The unique structure of the polar additives with oxygen-containing functional groups suggests that they could act as dispersion agents. 48 This might be enabled by the high loading of CBs (65 wt %) compared to the small traces of polar additives (5 wt %) in the present system, which facilitates the formation of the conductive networks. 4d,e, the logarithmic resistivity of the non-irradiated nanocomposites increased with increasing the temperatures and suddenly began to decrease near the melting point of HDPE (∼130 °C), which denoted an NTC effect.…”

“…The unique structure of the polar additives with oxygen-containing functional groups suggests that they could act as dispersion agents. 48 This might be enabled by the high loading of CBs (65 wt %) compared to the small traces of polar additives (5 wt %) in the present system, which facilitates the formation of the conductive networks. Figure 4d−f shows the pyroresistive behaviors and PTC intensities of the CBs−HDPE nanocomposites with the polar additives before and after EB irradiation.…”

Investigation of Cyclic Stability and Pyro-Resistive Properties in High-Density Polyethylene/Tungsten Carbide Composites Under Thermal and Electric Activation

“…The composite materials exhibit PTC behavior, effectively serving as current-limiting devices and regulating heating temperatures by adjusting the output energy. 33 Kim et al 34 investigated the variation of the minimum tripping current (I trip) for surlyn/low-density polyethylene (LDPE)/CB composite materials. When a current of 1.2 A is applied, the switching device triggers in approximately 10 s. However, when the current is below 0.7 A, the heat generated by the device and dissipated into the environment reaches an equilibrium state, rendering the PTC effect ineffective.…”