Temperature- and pressure-controlled insulator-conductor transition performance of flexible fluoroelastomer, tin bismuth alloy and carbon nanotube composites with a sandwich structure

Abstract

Recently, flexible insulator-conductor transition (ICT) composites have attracted much attention, and they are of great interest for many applications, including smart switches, sensors, and visualized circuits. In this study, flexible ICT composites based on fluorelastomers as the matrix and tin bismuth alloys (SnBi) and multiwalled carbon nanotubes (MWCNTs) as conductive fillers were prepared. The effects of the SnBi alloy and MWCNT contents and the testing temperature and pressure on the ICT properties of the flexible composites were investigated. The cyclic stability of the ICT properties for the composites was evaluated. The microstructure was characterized by scanning electron microscopy (SEM) analysis. The ICT mechanism of the composites was identified. The volume resistivity of the FKM/MWCNT/SnBi composites decreased by 11 orders of magnitude from 109 to 10−2 Ω·cm when the composites were compressed at 140 °C and then recovered to an insulation state after the composites were stretched several times with a strain of 20% at room temperature. The composites showed superior cyclic stability of the ICT performance for up to 100 cycles.