Effects of carbon black content and size on conductive properties of filled high‐density polyethylene composites

Rode

J of Applied Polymer Sci

et al. 2019

Polyamide 46 (PA 46) with carbon black (CB) has been subjected to a heat treatment. Crystallinity, specific heat capacity, crystalline melting peak temperature, thermal diffusivity, and electrical conductivity were measured. The crystallinity increases with duration of thermal treatment. The maximum value is dependent on the filler fraction. A lower CB content leads to a higher crystallinity at maximum tempering time. The crystalline melting peak temperature increases with decreasing filler fraction and duration of thermal treatment due to different crystal types and/or diverging geometric forms of the crystals. Thermal diffusivity and electrical conductivity act positively proportional to each other and increase with CB content and tempering time. The thermal diffusivity decreases with increasing temperature. The volume resistance of PA 46 is lowered by heat treatment. By CB addition in combination with a tempering process, the PA 46 can be transferred into a conductor. CB is moved by PA 46 crystals into amorphous regions forming conductive pathways.

Section: Discussionsupporting

confidence: 86%

Crystallinity, thermal diffusivity, and electrical conductivity of carbon black filled polyamide 46

Rode

J of Applied Polymer Sci

et al. 2019

Advances in Polymer Technology

“…But it decreases the degree of crystallinity. The reason may be that rigid CB particles can partly hinder the movement the HDPE molecular chains, which has an adverse effect on the crystallization [46].…”

Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Effects of POE and Carbon Black on the PTC Performance and Flexibility of High-Density Polyethylene Composites

Xue

Cai

et al. 2021

High-density polyethylene (HDPE)/carbon black (CB) is widely used in positive temperature coefficient (PTC) composites. In order to expand its applications to fields that need good flexibility, polyolefin elastomer (POE) was incorporated into HDPE/CB composites as a secondary thermoplastic elastomer phase to provide flexibility. The effects of POE and CB content on the PTC performance and flexibility were investigated. Micro morphology and crystallization behavior are closely related to PTC properties. SEM was conducted to reveal phase morphology and filler dispersion, and DSC was conducted to research crystallization behavior. The results show that the incorporation of 18 wt.% POE can decrease the percolation threshold of conductive carbon black from 22.5 wt.% to 16 wt.%. When the CB content is 30 wt.%, the room temperature resistivity gradually increases with the increasing content of POE because of the barrier effect of POE phase, and the PTC intensity is gradually enhanced. Meanwhile, the PTC switching temperature shifts down to a lower temperature. The incorporation of 18 wt.% POE significantly increases the elongation at break, reaching an ultrahigh value of 980 wt.%, which means great flexibility has been achieved in HDPE/POE/CB composites. This work provides a new method of fabricating PTC composites with balanced electrical and mechanical properties.

J of Applied Polymer Sci

“…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. As to another component of CPCs, the conductive fillers, including carbon system fillers, 43–47 metal fillers, 48–50 and metal ceramic system fillers 51,52 also play a critical role in achieving excellent performance of pyroresistive behavior by the outstanding conductivity and the capacity of constructing the conductive network.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

Zhang

2020

Conductive polymer composites with positive temperature coefficient (PTC) effect have gained intensive attention for the potential application in the smart heating field. The PTC reproducibility is significantly essential to guarantee the security and utility of PTC composites. Regrettably, during the repeated temperature cycles, the irreversible self-aggregation of conductive filler and the random reconstruction of conductive network lead to unsatisfactory performance of PTC reproducibility. Extensive efforts have been conducted to address this issue by strategies, including modification of fillers, cross-linking of a polymer matrix, hybrids of fillers, and application of binary polymer matrix. Nevertheless, there are very limited reviews about this issue. In this review, the recent advances in fabricating PTC composites with the enhanced PTC reproducibility have been systematically summarized. Meanwhile, the current challenges and future prospects of PTC composite are also presented. We hope that this review will provide some inspirations for designing PTC materials of long-term performance for commercial applications.