Effect of coefficient of thermal expansion on positive temperature coefficient of resistivity behavior of HDPE–Cu composites

Abstract

Positive temperature coefficient of resistivity (PTCR) characteristics of (high density polyethylene) HDPE-Cu composites has been investigated with reference to the conventional HDPE-CB (carbon black) composites. Plot of resistivity against temperature of HDPE-CB composites showed a sudden rise in resistivity (PTC trip) at 127 C, close to the melting temperature of HDPE. However, the PTC trip temperature (98 C) for HDPE-Cu composites was appeared well below the melting temperature of HDPE. Addition of 1 phr nanoclay in the composites resulted in an increase in PTC trip temperature of HDPECu composites, whereas no significant effect of nanoclay on PTC trip temperature was evident in case of HDPE-CB-clay composites. We proposed that the PTC trip temperature in HDPE-Cu composites was governed by the difference in coefficient of thermal expansion (CTE) of HDPE and Cu. The room temperature resistivity and PTC trip temperature of HDPE-Cu composites were very much stable upon thermal cycling. DMA results showed higher storage modulus of HDPE-Cu composites than the HDPE-CB composites. Thermal stability of HDPE-Cu composites was also improved compared to that of HDPE-CB composites.

PTCR characteristics of poly(styrene‐co‐acrylonitrile) copolymer/stainless steel powder composites

“…As observed, under 130 V AC and DC application, the composites could attain ≈ 94°C after 125 s and 150 s, respectively, which were close to the PTC trip temperature of the SAN/SS (80 wt %) composites. Thus, increase in resistivity of the composites near the PTC trip temperature resulted in a decrease in I of the composites, and hence no further increase in temperature was observed 34…”

Thermally induced double‐positive temperature coefficients of electrical resistivity in combined conductive filler–doped polymer composites

“…The storage modulus ( E ′ ) reflects the rheological behaviors of the composites, presenting an increase with increasing VO 2 content in Figure (a). The result is attributed to the VO 2 effects in reinforcing the interface stress transfer and restricting the segmental motion of polymer chains . At the same strain, the greater the storage modulus of the material, the greater the stress .…”

Positive temperature coefficient to resistively characteristics of polystyrene/nickel powder/multiwall carbon nanotubes composites

“…As observed, under 110V AC and DC application, the composites could attain ≈90°C after 125 and 150 s, respectively, which were close to the PTC trip temperature of the PS/Ni powder (40 wt%)/MWCNT (0.75 phr) composites. Thus, increase in resistivity of the composites near the PTC trip temperature led to decrease in I of the composites, and hence no further increase in temperature was observed [19–21].…”