Propertion And Research Of Carbon Nanotube/Silicone Rubber Composites Electromagnetic Shielding

For molding fast, simple preparation technology, easy processing and other advantages. Silicone rubber as the matrix conductive polymer composite materials have attracted more attention. The research object are carbon fiber, graphite, conductive titanium dioxide, silver, carbon nanotubes and so on, and then prepared conductive filler/Silicone rubber composite, and compare their performance. Focused on study the electrical conductivity and electromagnetic shielding properties of CNTs/Silicone rubber composite. Systematic analysis the influence of some processes with composite electromagnetic shielding performance and the microstructure of CNTs. including microwave processing, purification, shear dispersion, milling and so on.Research shows that microwave processing is able to eliminate the amorphous carbon CNTs and improve graphitization degree, and reduce structure defects of CNTs in previous treatment process; The purity of carbon nanotubes can reach above 95% by using mix acid which is synthesis by sulfuric acid and nitric acid, attributed to its oxidation; Mechanical milling will make the wall of CNTs have cleft, increase the number of tube-side, long ball will lead to the length of CNTs significantly reduce the carbon tubes, and take shape carbon particles. With the content of graphite is 5% the graphite/silicone rubber composite volume resistivi+ty decreased to 6.3×1010Ω·cm, Conductive polymer materials formed in matrix packing conductive network graphite content in 5～15wt% this interval, changes of material volume resistivity are small. With the content of graphite add to 30wt%, composite volume resistivity decreased to 105Ω·cm. CNTs has similar effects on carbon fiber composite conductive as graphite, With the content of carbon fiber is 20% volume resistivity decreased to 109Ω·cm, and when the content is 35% composite resistivity decreased to 10Ω·cm.With CNTs increasing, resistivity of composite materials were downtrend. With carbon nanotubes addtion to 12wt%, the volume of silicone rubber composites resistance reached 103Ω·cm anddecreased 10 orders of magnitude.So CNTs can greatly improve composite conductive properties.The properties of composition material improve as electric resistance decrease, for carbon fiber-based compound electromagnetic material, the increasing of carbon fiber content improve the shielding property and incresing loss of electromagnetic wave,which is attribute to form effctive electric conduction channel in high-content system. For 60% addition level of carbon fiber, the relatively smooth change in shielding performance. Conductive channels have been basically formed also, and then increasing content of carbon fiber has little effect, by the electromagnetic properties of its own. The shielding property of carbon fiber/composite materials can only reach 23dB in 0.03～1500MHz. Carbon nanotube obviously dominate carbon fiber in electric conduction, comparing with carbon fiber, lower content carbon nanotube can attain the similar shielding performance, when the content of carbon nanotube is 12wt% in composition, the shielding property of silicon rubber compound material can reach 27.5-30dB in 100-1000MHz.