Complicated resistivity‐temperature behavior in polymer composites

Abstract

ABSTRACT:The resistivity of different polymer composites is investigated in different temperature-changing processes, which demonstrates more complicated changing behaviors than that usually reported in literatures. The complicated resistivity-temperature (R-T) behaviors cannot be explained by current theories, and the contradictions of them with current theories are presented in this article. With the experiments, a new viewpoint on the R-T behaviors of polymer composites is proposed, i.e., the resistivity changes are attributed to internal stress generated when the morphology and structure of the composites undergo great changes. Based on this speculation, the complicated R-T behaviors of polymer composites can be well explained.

Designs of conductive polymer composites with exceptional reproducibility of positive temperature coefficient effect: A review

“…When the rapid expansion occurs near the melting point of a polymer matrix, the transportation of electron is hindered as the conductive path formed by filler clusters with direct contact is destroyed and further evolves into a wide gap. In the perspective of force domain, Li et al explained the evolution process of the PTC effect as well as the NTC effects followed in detail, based on the changes of internal stresses with temperature 68 . As we known, the electrical conductivity of CPCs is directly dependent on the relative position of conductive fillers, and the variation of the relative position must be the result of the variety of the force applying into fillers.…”

Tunable temperature-resistivity behaviors of carbon black/polyamide 6 /high-density polyethylene composites with conductive electrospun PA6 fibrous network

“…Hirano and Kishimoto 38 and Li et al. 39 studied the effect of heating rate on PTC behavior of SnO 2 (Sb)-coated TiO 2 /epoxy conductive thin films and CB/high-density polyethylene (HDPE) composites, respectively. Higher PTC intensity was observed under larger heating rate than that under a slower one.…”

“…Temperature-resistivity behaviors under different top temperatures have rarely been studied in the available literature. 39…”

Anomalous attenuation and structural origin of positive temperature coefficient (PTC) effect in a carbon black (CB)/poly(ethylene terephthalate) (PET)/polyethylene (PE) electrically conductive microfibrillar polymer composite with a preferential CB distribution

“…These two effects are often observed and their underlying mechanisms have been explained by many researchers, such as Kohler,26 Ohe and Natio,27 Meyer,28 and Voet,29 however, due to the complicated nature of CPCs (chemical structure, crystallinity,30 morphology of polymers;31 size,6 aggregate shape,32 concentration and distribution of the conductive fillers;3, 31 etc.) and multiform testing conditions (top testing temperature,33 and testing rate,8, 34 etc. ), the origin of PTC and NTC is still in dispute.…”

“…For a certain CPC, these two parameters are determined by the thermal programs predesigned for electrical properties‐temperature performance measurement, whose most common form are heating–cooling runs (HCRs). Though the influence of heating rate and top temperature on HCR has been discussed,8, 33, 34 the previous studies were mainly focused on the PTC and NTC effects of one or two HCRs. Systematic study of the microstructure development of the conductive network and the variation of the PTC and NTC effects in multifarious thermal fields has been barely touched up to now.…”