Preparation and Properties of Chemical Resistant Conductive Composites with Restrained Negative Temperature Coefficient Behaviour Based on Mechanochemically Devulcanised Waste Fluoroelastomers

Abstract

The presence of negative temperature coefficient (NTC) effect is harmful to temperature auto-control and also hinders the application of self-regulating heater materials. Mechanochemically devulcanised waste fluoroelastomer (FKM) can hinder the aggregation of conducting fillers and inhibit the NTC effect. Herein, we report for the first time that the devulcanised FKM can be used as low cost but effective functional filler for making chemical resistant conductive composites with restrained NTC effect. The NTC effect was notably restrained via introducing devulcanised FKM into the carbon black-filled poly(vinylidene fluoride) composites. A platform with a volume resistivity higher than 106 Ω•cm was observed at temperature range of 167–180°C. The crystallization imperfection and limited mobility of carbon black induced by the well dispersed FKM powders are responsible for the delay of NTC effect. Furthermore, the mechanical properties of the composites were significantly improved through the mechanochemical pretreatment of FKM. Meanwhile, the devulcanised FKM-filled composites have excellent chemical resistance. The stable resistivity in a wide temperature range of the prepared low cost composites gives them attractive prospects as over current and temperature sensor materials.