On The Resistance-Deformation Property Of Carbon Black Filled Silicone Rubber

With the development of the society, smart textiles develop vigorously. As the core part of smart textiles, the development of embedding sensors cannot meet the requirements, which include flexibility, deformability, comfortability etc. Because of it, many traditional sensors cannot be used on embedding purpose. One of the objectives of this study is to find a suitable material system for the purpose of embedding sensors for smart textiles.As the core part of smart textiles, embedding sensors must be flexible and wearable. To give embedding sensor flexibility there are two common approaches, i.e. development of textile sensors and piezoelectricity film sensors. The former can measure fabric strain but with low precision and poor repeatability because of the relaxation properties of irregular slipping between conductive fibers. The latter has the problem of flexibility. Though it can withstand high pressure along the thickness direction, it cannot bear large scale bend. In addition, it can measure only dynamic signals and shows less feasibility to static signals. The development of carbon black filled silicon rubber shows promising possibility as embedding sensors because of good flexibility and electric properties upon mechanical loads. However, the range of electrical resistance is rather narrow showing limited sensitivity. Furthermore, during the preparation process, carbon black can easily reunite. So it disperses unevenly. This affects the stability of the piezoresistance property.In order to develop an embedding sensor with satisfied flexibility and electrical sensitivity, this study focuses the following four tasks:(1) Try two of the exiting methods, i.e. screen printing and mechanical mixing, to find a suitable method for fabricating specimens of carbon black filled silicone rubber. After evaluation the processing technology and technical availability, the method of mechanical mixing is chosen.(2) Build the experiment platform to measure the sensor properties of carbon black filled silicone rubber material. Then determine the corporate ratio of the component. Measure the pressure sensitivity, piezoresistance repeatability, hysteresis property and so on. The mass fraction of carbon black in carbon black filled silicon rubber is 12%. With the pressure increasing, the resistance becomes small. It has good piezoresistance repeatability. To indicate the piezoresistance relaxation property using pressuring resistance/releasing resistance it is 12.7%.(3) Explore the way to improve the piezoresistance performance of the composite material. We separately try three methods. Use two kinds of carbon black with different particle size to blend. Mix nano-silica. particle to the composite material. Treat in different atmosphere with plasma. Through these methods, we improve the piezoresistance property. Carbon black with different particle size mixing can increase the piezoresistance linearity and pressure sensitivity. When the mass fraction of nano-SiO2 is 3%, it has the best effect of decreasing resistance. After plasma treated, the pressure sensitivity can be raised.(4) Apply the material practically. Use this material to make flexible fabric strain sensor. We fit the sensor to rubber gloves and measure the bend of the finger with it. Then we rebuilt the movement of the finger by VB programs. It shows that the result has good consistency with the actual movement. The sensor is flexible and elastic. So it doesn't influence the movement.