Processing, Structure, Properties, and Joule Heating Application of Polyacrylonitrile /Carbon Nanotubes Composite Fibers
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Carbon fibers are widely used in aerospace, sporting goods, and wind turbine blades for reinforcing composite materials, due to their high tensile strength, modulus, and low density. However, due to the relatively high cost of production compared to some common metals such as steel or aluminum, carbon fibers have not been widely used in many other applications such as in the automobile industry. The reduction of carbon fibers’ cost is useful for a wide range of applications. Currently, polyacrylonitrile (PAN)-based carbon fiber dominates over 90% of the carbon fiber market. PAN-based carbon fibers typically are made from PAN precursor fibers after stabilization and carbonization processes. Stabilization is regarded as the rate-limiting step and requires a long residence time of about 2 hours. Stabilization generally takes place in a convective heating oven between 200 to 300 °C. In this thesis, the Joule heating process was used to replace convective heating for PAN stabilization, by incorporating carbon nanotubes (CNTs) in the fiber to produce the required fiber conductivity for resistive heating. The processing, structure, properties and Joule heating were shown for PAN/CNT fibers in this thesis. Stabilization through Joule heating was demonstrated for bi-component core-sheath PAN-PAN/CNT fibers with less than 5 wt% CNT, in both a batch and continuous process.