Study On Piezoresistive Mechanism Of Carbon Nanotubes/Silicone Composites

The phenomenon that the resistivity of the composites changes with the pressure is called piezoresistive effect. The process that the resistivity of the composites increases with the pressure is called positive resistance coefficient effect(PPCR), otherwise, negative resistance coefficient effect(NPCR). Generally, the composites strain under pressure, at the same time, the matrix is elastically compressed and the distance between the conductive particles comes down, leading to the formation of more conductive channels, which reduces the resistance of composites. The process is called the NPCR effects, such as the composites which are filled with carbon black. When the conductive fillers are carbon nanotubes, the PPCR effect happens. Good pressure sensitive properties of composites can be obtained due to the excellent chemical and physical properties of carbon nanotubes. MWNT/RTV composites are pressure-sensitive conductive materials, which exhibit linear, high pressure-sensitivity and repeatability.This paper introduce the preparation of electrical conductive rubber-based composites by three-roll mill, with silicone(SR) as matrix and carbon nanotubes(MWNT) as the first filler and different contents of CB, A12O3 or SiO2 as the second filler. The pressure-resistance of MWNT/the second fillers/RTV composites and the conductive mechanism of MWNT/RTV composites are mainly investigated. Moreover, the paper study on the modification of fillers and the dielectric properties of MWNT/the second fillers/RTV composites.The research shows that the addition of CB reduces the pressure sensitivity of composites, On the contrary, Al2O3 and SiO2 increase it. The results show that the second filler will support MWNT under pressure and increase their orientation. The mechanism of negative resistance coefficient effect (PPCR) happened in MWNT/RTV composites, which means that CNTs display orientation at the vertical direction of pressure.