Positive temperature coefficient and time‐dependent resistivity of carbon nanotubes (CNTs)/ultrahigh molecular weight polyethylene (UHMWPE) composite

Abstract

ABSTRACT:The carbon nanotubes/ultrahigh molecular weight polyethlene (CNTs/UHMWPE) conductive composite with a low percolation threshold had been successfully fabricated, and CNTs were only dispersed in the interface of matrix particles. Some factors, including CNTs concentration, processing temperature, and the time of isothermal treatment, which could exert influence on the positive temperature coefficient effect of the composite, were investigated. Similar with negative temperature coefficient effect, the resistivity decreased during isothermal treatment above the melting point of UHMWPE, which could be thought to be a relaxation process originated from movement of molecular chains. This relaxation, also a process of CNTs aggregating to reorganize the conductive network, was testified as a function of time, temperature, filler concentration, and heating rate.

Biodegradable poly(butylene succinate‐co‐butylene adipate)/multiwalled carbon nanotube nanocomposites: Preparation, morphology, and crystallization behavior

“…Carbon nanotubes (CNTs) were first reported by Iijima in 1991;4 they possess excellent mechanical, electrical, and thermal properties. Some polymer/CNTs nanocomposites have been reported in the literature 5–8. It is clear that the combination of biodegradable polymers with a very small quantity of CNTs is of great interest and use from both academic and industrial viewpoints 9–19…”

Properties of UHMWPE fabric reinforced epoxy composite prepared by vacuum-assisted resin transfer molding

“…The maximum tan δ, and the temperatures of the maximum tan δ, are presented in Table 3. The profiles of the UHMWPE fiber showed α-relaxation peak around 80 o C, which is due to motions of the interfacial regions (e.g., tie molecules, fold, loops) that require chain mobility in the crystal [8,9,11]. The relaxation around 130 o C was from melting.…”

Influence of the Compaction Temperature on the Electrical and Mechanical Properties of the Segregated Conductive Ultrahigh Molecular Weight Polyethylene/Carbon Nanotube Composite

“…Gao et al [20,21] studied the influence of the compaction retention time on the relaxation of resistivity for UHMWPE=CNT system, proposed that the residence time would lead to more violent movement of matrix molecules, so the re-aggregation of CNTs takes place more easily, manifesting a lower volume resistivity. Mierczynska et al [23] discussed how the sintering pressure affected the electrical property of UHMWPE=CNT, raised a conclusion that conductivity slightly increased with the processing pressure and then reduced as the processing pressure was further increased.…”

“…Because of specific distribution of the conductive particles on surfaces of the polymer powders and the unique compacting or sintering method, the processing condition inevitably influences the microstructures, mechanical and electrical properties of the segregated CPCs [19][20][21][22][23] . Grunlan et al [19] investigated the effect of the drying temperature on the percolation threshold of the carbon black-filled poly(-vinyl acetate) latex-based composites, and found the percolation threshold increased with the drying temperature, due to the cutoff of the conductive pathways that would otherwise be part of the ''infinite'' network in a more weakly coalesced composite.…”

“…The segregated network has been extensively studied in recent years [13][14][15][16][17][18][19][20][21] . Gao et al used a liquid-assisted dispersion method under ultra-sonication and intense mechanical mixing to achieve an ultra-low percolation of 0.072 vol.…”