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

Abstract

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.

Positive/Negative Temperature Coefficient Behaviors of Electron Beam-Irradiated Carbon Blacks-Loaded Polyethylene Nanocomposites

“…Normally, the volume expansion of a polymer, originating from the melting of the crystalline region and thermal expansion, is the key factor influencing the PTC effect of polymeric composites. A major peak was observed in all endothermic curves, corresponding to the melting points of the CBs–HDPE nanocomposites in the temperature range of 130–150 °C . The peaks shifted to slightly lower temperatures when the polyol or ionomer was incorporated in the nanocomposites, meaning the T m decreased due to their inherent low T m of the polar additives.…”

“…A major peak was observed in all endothermic curves, corresponding to the melting points of the CBs–HDPE nanocomposites in the temperature range of 130–150 °C. 43 The peaks shifted to slightly lower temperatures when the polyol or ionomer was incorporated in the nanocomposites, meaning the T m decreased due to their inherent low T m of the polar additives. By the same token, the decrease of X c was also found in the polyol-CBs–HDPE and the ionomer-CBs–HDPE.…”

Preparation and characterization of thermo‐responsive shape memory polycaprolactone/poly(ethylene‐co‐octene) blends for 4D printing

“…[19][20][21][22] POE is a type of polyolefin elastomer with excellent energy storage capacity. [23][24][25][26][27] In this work, the respective properties of PCL and POE were combined by melt blending, and the blends exhibit desirable mechanical properties while retaining excellent elasticity. Compared to previous studies, the novel shape memory PCL/POE blends possess excellent shape memory ability (the R f up to 100% and R r above 87%) and were used in 3D printing technology.…”

Achieving superior pyroresistive reproducibility at HDPE/PVDF composites with tailored conductive phase size

“…To overcome these drawbacks, the combination of immiscible polymer blends [35][36][37][38][39][40][41] could be an alternative strategy based on the following two factors: (i) the PTCs will be confined in the immiscible polymer with higher T m when it is manifesting PTC property and (ii) the binary polymer system has superiority to control resistance of room temperature in practical production due to the expanded ranges of percolation derived from the additional phase morphology percolation transition. Based on immiscible high density polyethylene (HDPE)/ polyvinylidene fluoride (PVDF) system, Zhang et al 37 have reported that the PTCs with "sea-island" morphology exhibited preferable PTC reproducibility.…”