Carbon black-filled polypropylene as a positive temperature coefficient material: effect of filler treatment and heat treatment

Abstract

Polymer-based positive temperature coefficient (PTC) composites are of special interest because they have great potential in temperature-sensitive devices. In this work, composites based on polypropylene and carbon black (CB) particles were prepared by solution blending. The electrical and mechanical properties of composites were measured when CB particles were treated with silane coupling agent before added to the PP matrix. It was found that CB treated by coupling agent exhibited a higher filler-polymer interaction which was reflected in the improvement of the mechanical properties and the modification of electrical conductivity of composites, especially when measured against the temperature. The effect of heat treatment on the electrical conductivity, PTC behavior and mechanical properties was also studied. It turned out that the optimal heat treatment condition of composites was at 120°C for 3 h. The differential scanning calorimetry analysis and X-ray diffraction analysis revealed that heat treatment could increase the crystallinity of composites, so that the PTC intensity increased.

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

“…Nonetheless, it is approved that the reversible deconstruction or reconstruction of the conductive network can fundamentally improve the performance of PTC reproducibility (Figure 1). Great progress has been made to improve the PTC reproducibility, and the typical strategies are shown as Figure 2, including modification of fillers, 53 crosslinking of polymer matrix, 69 hybrids of fillers, 70 and application of binary polymer matrix 54 . As the common strategy for enhanced PTC reproducibility, the modification of fillers improves the compatibility between filler and polymer, so that not only the large aggregate hardly forms but also the conductive fillers can be reversibly pushed out or pulled into their original positions, with the help of physical entanglement or chemical bonding between polymer matrix and the molecule grafted on the surface of filler.…”

“…Great amounts of effort have been done to diligently eliminate that negative variation for enhanced PTC reproducibility which can ensure the security and practicability of PTC composites. For instance, the modification of conductive fillers, an available strategy, can improve the PTC reproducibility by strengthening the thermodynamic compatibility between fillers and matrix 22,53 . Besides, the strategy, application of binary polymer matrix, to fabricate composites with high PTC reproducibility has attracted a lot of attention in recent years 54 .…”

Preparation of Controllable and Repeatable Crystalline States through Step-by-Step Self-Nucleation Programming and Its Application for Improving the PTC Reproducibility of trans-1,4-Polyisoprene/Carbon Black Composites

“…However, due to the poor compatibility between the matrix and filler, as well as the random deconstruction and rearrangement of the conductive network after complete melting and crystallization, the disadvantage of poor reproducibility of PTC has been exposed gradually . Researchers have proposed methods such as two-phase matrix blending, filler modification or hybridization, and cross-linking of the molecular chain to improve the reproducibility of PTC, and all of these solutions require the addition of additional components. This prompted us to think, since the PTC effect of semicrystalline polymers is generated by crystal melting, can the reproducibility of PTC be improved solely by adjusting the crystalline states?…”

Synergistic augmentation of polypropylene composites by hybrid morphology polyaniline particles for antistatic packaging applications

“…Due to low density, ease of processability, corrosion resistant nature and tunable electric properties these electrically conductive polymers are widely used as antistatic media, selfregulated heating materials, sensors, energy storing devices and design of electro-optical devices [2][3][4]. Polypropylene, polyethylene, ultra-high molecular weight polyethylene, polystyrene, polyamides etc have been extensively used for fabrication of electrically conducting polymer composites [5]. In order to impart conductivity, these polymers are filled with conductive polymers.…”