Preparation And Performance Of Ultra-conductive Carbon Black Filled Silicone Rubber

Electrical conductive polymer materials comprise intrinsical conductive materials and conductive composites. Conductive polymer matrix composites have traditional mechanical properties as polymer materials, and have advantages of easily molding and low prices. Now Conductive polymer matrix composites have been widely used in many fields such as electronic, materials, chemical industry, aviation and spaceflight.Conductive silicone rubber is one of conductive polymer matrix composites. Silicone rubber is linear macromolecular elastomer with Si-O. Compared with natural rubber and other organic synthetic rubber, silicone rubber has many excellent properties, such as heat-resistance, easy mould unloading, ozone- resistance, oxygen-resistance, light-resistance and climate-resistance. The electrical resistance of silicone rubber mixture changes little during mixing and preservation because of low viscosity if silicone gum and weak appetency for carbon blacks. Conductive silicone rubber has become the most widely used conductive rubber due to its advantages mentioned above and the inherent excellent properties of silicone rubber.As one of conductive filler for polymer composites, carbon black have many advantages, such as resourceful, low prices, low density, easily processing and stable property. CB has well dispersibility in polymer matrix, and excellent electrical conductivity will be obtained by selecting certain CB, filler loading and processing methods. Generally the higher the dibutyl phthalate absorption, the lower content of H, O, volatile, greyhound and moisture, and there is better conductivity.The conductive mechanisms of conductive polymer matrix composite are very complex which have been widely studied since the appearance of conductive composite. There are many viewpoints about conductive mechanisms, which can be concluded into three: macroscopical seeping theory, electron channels theory; microcosmic quantum mechanics, electron tunneling theory; microcosmic quantum mechanics, emission of electric field theory.The conductivity of CB filled silicone rubber is influenced by many factors. Excessive curing agent will decrease the conductivity; Different conductivities exhibit with adding different fillers. The conductivity will decrease with the hybrid of silica and CB; Influence of thermal treatment on electrical conductivity with deferentconducting mechanism is deferent. Thermal treatment decreases the conductivity of conductive silicone rubber when the dominant conducting mechanism is contact conduction. Thermal treatment increases the conductivity of conductive silicone rubber when the dominant conducting mechanism is electron tunneling; Different the kinds of carbon black result in deferent blending time. The conductivity increased greatly influence by long time shear destroy when the structure is complex. On the contrary, little influence when the structure is simple.In order to obtain better electrical conductivity and processing properties conductive silicone rubber, conductive silicone rubber were prepared by mixture of CB, and the conductivity and mechanical properties were discussed.The second percolation threshold was found by the addition of deferent size carbon black, which is deferent from the percolation threshold rule filled with one size conductive filler. The reason of appearing second percolation threshold was induced according conductive mechanism.BP2000 super conductive carbon blacks have good conductive properties, and the conductivity of materials will be improved by little addition. But the mechanical properties were greatly influenced by BP2000 super conductive carbon blacks when adding into silicone rubber. Modified BP2000 super conductive carbon blacks were obtained by coupling agent modification. The technical properties and addition concentration were increased, which greatly improved the mechanical properties of conductive rubber.