Study On The Electrically Conductive Performance Of Carbon Fiber/Polymer Composites

The electrical conductivity of polymers can be increased by the addition of conductive fillers, including various forms of carbon fibers, carbon black, graphite and metal powder. The resulting composites can be used in applications where metals have typically been the materials of corrosion, and the ability to be readily adapted to the needs of a specific application.A more efficient materials design can be achieved through the use of electrical conductivity models. The use of accurate models aids in the understanding of the mechanisms that control conductivity in these composites, and provide insight into the properties important to achieving desired conductivity levels. In addition, the use of models can reduce costly experimental work, as well as the consumption of materials, through the ability to target a desired conductivity level for the composite based on a set of calculations.The first objective of this project was to analyze several structural factors which affect the electrical conductivity of chopped-carbon fiber filled thermoset polymer composites in order to propose an electrical conductivity model for the development of conductive carbon fiber-thermoset polymer composites. The second objective was to study the temperature-resistance properties of carbon fiber-thermoset polymer composites which enable us to better understand the conductive mechanism. In addition, we tried to explore a new and special phenomenon—the electromagnetic emission of this kind of material.The result of the analysis showed that fiber aspect ratio and orientation evidently affect the conductivity of composites. The greater aspect ratio or the smaller mean orientation angle the better conductivity of composites and the composites' conductivity as well as its temperature stability was remarkably enhanced as the result of the use of the surface treated carbon fibers. It's also found that the volume expansion is a main factor in resulting in the composites' PTC behavior which is more sensitive and evident when the filler fraction is within the percolation region. Based on above-mentioned studies, we proposed the conductivity mechanism of chopped-carbon fiber filled thermoset polymer composites and established a structure-oriented model based on Weber's model. The experimental data fit the model well. Moreover, it has been found that the composites have an obvious electromagnetic emission during breakage. This property makes carbon fiber/polymer composites a possible intelligent material, and will enlarge the application field of this kind of materials.