Resistivity‐temperature behavior of carbon fiber filled semicrystalline composites

Abstract

Carbon fiber (CF) filled low-density polyethylene (LDPE) composites were prepared by the conventional melt-mixing method. The distribution of CF in the composite was studied by wide-angle X-ray diffraction (WAXD) and scanning electron microscope (SEM) observations. A phenomenological model was proposed to illustrate the resistivity-temperature behavior of CF-filled semicrystalline composites. The effects of the content and aspect ratio of CF on the positive temperature coefficient (PTC) and the room temperature resistivity were elucidated. A balance between the PTC intensity and the room-temperature resistivity can be achieved by using a mixture of CFs with low and high aspect ratios. The negative temperature coefficient (NTC) phenomenon can be effectively eliminated by crosslinking under ␥-ray radiation, and the crosslinked composite exhibits a higher PTC intensity and PTC transition temperature than the noncrosslinked counterpart.

Investigation of electrical and dielectric properties of prelocalized graphite/poly(vinyl chloride) composites near the percolation threshold

“…Polymeric materials are usually insulators. Insulating polymers can be made conducting [1][2][3][4][5][6][7][8] by mixing electrically conducting fillers. The conducting polymer composites can be easily shaped into various complicated forms by the traditional technique of extrusion and injection-molding.…”

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

“…Generally, a crystalline polymer is selected to ensure the valuable capacity of sensing and self‐regulating for the reasons that the conductive network formed in a selected crystalline polymer is destructed by drastic volume expansion during crystalline melting and the concentration of conductive fillers are diluted with the migration of fillers into melted crystalline regions 25–27 . The PTC intensity of composites with a high crystallinity matrix can even exceed seven (the increase of resistance above seven orders of magnitude), showing super sensibility of resistance with elevating temperature 28 . Furthermore, an abundance of crystallinity polymers such as poly(vinylidene fluoride) (PVDF), 29–32 polypropylene, 33–36 polyethylene (PE), 37–39 ethylene vinyl acetate copolymer (EVA) 40–42 are the candidates to satisfy the applications in different temperature ranges because each of them with unique melting point presents high sensibility of resistance in respective melting range.…”

Electrical resistance behavior of vinylester composites filled with glass-carbon hybrid fibers

“…The dispersion of a conductive filler, such as carbon black (CB), carbon fiber (CF) or metal powder into an insulative polymer matrix can yield the conducting polymer composites [1][2][3][4][5][6][7][8] . These composites are widely used in the fields of electromagnetic interference shielding, conducting polymer, electrostatic dissipative wires, positive temperature coefficient materials for switch and liquid or chemical vapor sensors.…”