Carbon Nanomaterial/silicone Rubber Piezoresistive Properties And Fabric Pressure Sensor Preparation

With the development of intelligent products,intelligent textiles,intelligent clothing and so on have become the research hotspots.In order to detect the pressure between fabric and human body,this subject mainly studies fabric pressure sensor.And it is convenient for people to directly understand their physiological signs parameters and motion status.The sensor must have good flexibility and wearability due to the integration of the sensor into the fabric or garment.So the subject selected silicone rubber（SR）as a flexible substrate,carbon black（CB）and multi-walled carbon nanotubes（MWCNT）as conductive filler to prepare fabric pressure sensor.Firstly,CB and MWCNT were oxidized with nitric acid（HN03）and sulfuric acid（H₂SO₄）to improve the dispersibility of CB and MWCNT.The oxidized CB and MWCNT were modified with silane coupling agent（KH550）to further improve the dispersibility of CB and MWCNT and their compatibility with silicone rubber.Then,functionalized CB and MWCNT were surface modified with anionic and cationic surfactants,respectively,so that the surfaces of CB and MWCNT had negative and positive charges.A novel "grape string" CB/MWCNT structure was obtained by electrostatic assembly method.Finally,the functionalized CB,MWCNT,the electrostatic assembled CB/MWCNT and silicone rubber were mixed and vulcanized to prepare the flexible piezoresistive material.The functionalized CB and MWCNT were characterized using XPS and FTIR.It shows that the oxygen group is increased and the KH550 is successfully grafted.The phenomenon of the settlement volume test shows that the functionalization improves the dispersion stability of CB and MWCNT.The electrostatic assembly effect of CB/MWCNT and its dispersion in silicone rubber matrix were analyzed by TEM and SEM.It shows that the electrostatic assembly is best when the ratio of CB to MWCNT is 3:2 and they can be uniformly dispersed in silicone rubber.The mechanical,electrical conductivity,piezoresistive properties and relaxation behavior of CB/SR,MWCNT/SR and CB/MWCNT/SR were analyzed by testing the resistance.The results show that the piezoresistive characteristics of the CB/MWCNT/SR with the electrostatic assembly ratio of 3:2 and the volume fraction of CB/MWCNT of 22%are obvious,and the relaxation time is short.And so the fabric pressure sensor can be prepared by integrating the sensor element with the fabric.Connecting information processing circuit,data acquisition system and computer with intelligent insoles or smart clothes,we can display information of foot pressure or human body’s pressure.