Conductive Properties Of Carbon Black Filled Conductive Silicone Rubber Research

As the rapid demand for the conductive polymeric materials in all walks, the application of the conductive polymeric materials widens a lot. The conductive polymeric materials could be divided into two types:structural conductive polymeric materials and composite conductive polymeric materials. For their simple manufacturing, low cost, mature technology, the composite conductive polymeric materials were widely used. The filling composite conductive polymeric materials were used most widely. Carbon black filling conductive silicone rubber belonged to the filling composite conductive polymeric material.Carbon black was chosen as the conductive filling material in this research, and the theoretical and experimental researches were performed to investigate the electronic properties of the conductive silicone rubber. Based on the conductive channel theory and the tunnel effect theory, the current forming process, conductive mechanism, and piezoresistive effect of the conductive rubber were studied, and the piezoresistive model based on tunnel effect theory was especially discussed.The experiment samples were made. The plans, methods and contents of the experiment were determined. By doing a number of experiments, the optimal raw materials and ratio of match were proposed, and the conductive silicone rubber with piezoresistive effect was made. The experiments of identical filling material with different filling amounts, and different filling materials with identical filling amounts were analyzed. It was found that for the same filling material, the effect of different filling amounts on the piezoresistive property of conductive silicone rubber was different. As the filling amount increased, the piezoresistive property gradually changed from non-linear relationship to linear relationship. The piezoresistive property of conductive silicone rubber whose filling material was different while its filling amount was the same, varied with the basic characteristics of the filling material. It was shown that the partical diameter of the filling material was smaller, the conductive property of the samples was better, and the piezoresistive property was more linear, which would provide some base for the further research of the conductive silicone rubber. The modification mechanism of adding nano modifying material into the conductive polymer material was investigated. For its four effects, the nano modifying material has some excellent property which the traditional materials don't have. The nano particles have a better compatibility with the rubber base, which will promote the dispersion of the carbon black, and will increase the conductive property of conductive silicon rubber. There are many active groups on the surface of the nano material, whose hydroxyl can combine with the oxygen atom on the polymeric chain to form hydrogen bond, which can increase strength and toughness. By adding nano-SiO2and nano-Al2O3, the conductive silicone was loaded and unloaded repeatedly. It was found that the inner structure of the rubber tended to be stable, and stable, continuous conductive tunnels are formed. Its repeatability was better than that without adding nano particles.The better conductive performance of the conductive rubber silicone could be made from carbon black. But the effect of different particle diameter on polymeric chains was different, which resulted in that the carbon black distribution was not uniform, and decreased the other performance of the rubber. It was harder for the white carbon black disperses in the rubber than the carbon black did. In addition, if it was mixed with carbon black, their mutual aggregation would increase, which would do harm for the conduction of the rubber. However, it could improve its strength. Therefore, choosing the appropriate carbon black blends could improve the comprehensive performance of conductive silicone rubber.