Study On The Preparation And Properties Of Conductive Composites With Carbon Black Filled Unsaturated Polyester Resin

Since the1970s, carbon black filled conductive composites used as new functional materials has been developed quickly. It has been widely used in electronics, energy, chemistry industry and other fields because of its capacity of electrical properties and mechanical properties adjusting within wider range, low cost and easy molding. The internal connection between micro-dispersed state of the filler in matrix solution and macro-properties of material has been prepared becomes an important target for the scientists based on the important influence on the macro-properties created by micro-dispersion of the filler in the matrix solution.A series of conductive composites have been prepared using unsaturated polyester resin as matrix, acetylene black carbon for conducting filler and glass fiber to be reinforced materials for this paper. The changes of viscosity of the material before solidified in different content of carbon, stirring speed and stirring time are studied, the electrical and mechanical properties of material after solidified, microstructure of carbon black in resin state are also studied, and besides the carbon black is treated with coupling agent to analyze the impact of these factors mentioned above on the material properties and to contrast the change of material properties before and after coupling agent treatment.The amount of styrene absorbed by carbon black after coupling agent KH570treatment change from3.640cm3/g to1.854cm3/g, reducing by about half showed by the experimental of carbon black absorbing styrene. The content of carbon black has strong influence on the viscosity of carbon black filling in the unsaturated polyester resin which is tested with rotating viscometer, showing that higher content of carbon black correspond with the greater viscosity. The value and value change of viscosity of the system after the coupling agent treatment become lower than before treatment. The minimum of value-added of viscosity is19500mPa·s when system has been palced for24hours after being stirred with2500r/min stirring rate, and is13200mPa·s when system has been palced for24hours after being stirred with2500r/min stirring rate stirred for20minutes. It is most uniform and stable for the dispersion of carbon black in the system when value-added of viscosity is13200mPa·s and system to be stirred for20minutes. Observing microscopic structure of materials with SEM and testing the electrical and mechanical properties of materials to study the intrinsic connection between micro-dispersion of carbon black and macro properties of materials on the basis of the above study gets conclusions as following:(1) Through testing volume resistivity of the material under different carbon black content showing that when carbon black content is5%produce percolation phenomenon, and volume resistivity value is1.07×105Ω·cm. Percolation phenomenon does not appear after treatment with silane coupling agent, but volume resistivity value is an order of magnitude lower than before treatment when carbon black content is6%.(2) Through studying the influence of mixing speed, mixing time on the electrical properties of materials showing that the minimum electric resistivity of materials is4.27×104Ω·cm with2000r/min stirring rate, and the minimum electric resistivity of materials is1.07×106Ω·cm with1500r/min stirring rate after treatment with silane coupling agent, indicating that the better electrical properties can be got in the lower stirring rate. The minimum electric resistivity of materials is1.07×105Ω·cm with20minutes mixing time, and the minimum electric resistivity of materials is2.0×106Q·cm with20minutes mixing time after treatment with silane coupling agent, indicating that electric resistivity of materials is no longer reduced significantly before and after treatment with silane coupling agent with the extension of the mixing time.(3) The flexural strength increases and the increasing rate slows down gradually with the content of carbon black changing from1%to6%.(4) The decentralized state and stability of carbon black dispersed in the resin can be improved by the coupling agent, and the coupling agent can also help glass fiber immerging in the black-resin mixed system.Conclusions are got according to the study of CB/CF/GF/UPR conductive composites prepared preliminarily as following:flexural strength and conductiveity of material are enhanced by increasing the content of carbon fiber, which indicating that mechanical and electrical properties can be improved by the carbon fibers. Carbon fibers distributing desultorily in the resin are observed using SEM help forming conductive pathways.