Economical conductive graphite‐filled polymer composites via adjustable segregated structures: Construction, low percolation threshold, and positive temperature coefficient effect

Abstract

The economical graphite‐filled thermoplastic urethane/ultra‐high molecular weight polyethylene (TPU/UHMWPE) composites with the segregated structure were constructed by the combination of mechanical crushing and melt blending method. The low percolation threshold of 1.89 wt% graphite in the adjustable segregated composites was obtained and high electrical conductivity was about 10−1 S m−1 at 10 wt% graphite loadings owing to the formation of three‐dimensional conductive networks. Moreover, when the graphite loadings were over the percolation threshold, the remarkable positive temperature coefficient (PTC) effect of electrical resistivity for TPU/UHMWPE‐Graphite composites were achieved, originating from the combined thermal motion of TPU and UHMWPE. Meanwhile, the outstanding repeatability of PTC effects was obtained after 5‐time cycles. Therefore, economical conductive polymer composites were still the promising field in the practical application of PTC materials.

Influence of different dry‐mixing techniques on the mechanical, thermal, and electrical behavior of ultra‐high molecular weight polyethylene/exhausted tire carbon composites

“…This finding can be explained considering that, due to the segregated morphology of the UHMWPE/ETC systems, the increase of particle loadings does not promote an increment of the polymer/particles interfacial area. More in detail, in the composites containing 1 wt% of ETC, the formation of particle‐rich channels occurs, inducing some restrains of the relaxation process of UHMWPE macromolecules and an increase of the low‐frequency complex viscosity 46,47 . The addition of higher amounts of ETC causes a modest rise of the complex viscosity, as the introduced particles contribute to the increase of the particle path thickness only.…”

“…More in detail, in the composites containing 1 wt% of ETC, the formation of particle-rich channels occurs, inducing some restrains of the relaxation process of UHMWPE macromolecules and an increase of the low-frequency complex viscosity. 46,47 The addition of higher amounts of ETC causes a modest rise of the complex viscosity, as the introduced particles contribute to the increase of the particle path thickness only.…”

High resistivity‐temperature effect of resistivity for economical and facile conductive polymer composites with low percolation threshold via self‐constructed dual continuous structure

“…Nevertheless, the processing technology for CPCs with specific structures was usually complicated. For example, in our previous reports, 35 based on the segregation system on thermoplastic polyurethanes/ultra-high molecular weight polyethylene-flake graphite (TPU/ UHMWPE-FG) composites by the melt blending, the low percolation threshold (1.89 wt% of FG) and good PTC effects could be achieved. However, the processing technology in this system was complex, restricting the practical application.…”

Segregated highly conductive linear low‐density polyethylene/graphene nanoplatelet composite through aqueous dispersing and self‐leveling method

“…However, in molding these polymers, certain pressure has to be applied due to the extremely poor melt fluidity. For example, the thermoplastic polyurethanes (TPU)/UHMWPE‐graphite composites were constructed by mechanical crushing and hot‐pressing method 31 . Li et al reported a segregated structure was constructed for POE/multi‐walled CNT (MWCNT) elastomeric conductive composites with chemically cross‐linked POE granules under a pressure of 10 MPa 32 .…”

“…For example, the thermoplastic polyurethanes (TPU)/UHMWPE-graphite composites were constructed by mechanical crushing and hot-pressing method. 31 Li et al reported a segregated structure was constructed for POE/multi-walled CNT (MWCNT) elastomeric conductive composites with chemically crosslinked POE granules under a pressure of 10 MPa. 32 In addition, in order to improve the mechanical strength of the s-CPCs, a third material is usually needed to act as interfacial bonding.…”