Viscoelastic properties of coil carbon nanotube-coated carbon fiber-reinforced polymer nanocomposites

Abstract

Strong interfacial bonding is necessary between carbon fiber and polymer matrix to take advantage of carbon fiber-reinforced polymer composites in structural applications. An attempt has been made to improve the interfacial bonding by coating coiled carbon nanotubes on carbon fiber surface through a single-step chemical vapor deposition process. Coiled structures were synthesized on nickel-coated carbon fiber by using thiophene as a sulphur impurity and acetylene as a carbon precursor. The coiled carbon nanotube-coated carbon fiber and epoxy were used, respectively, as the reinforcement and the matrix to form carbon fiber-reinforced polymer composites. The role of coiled carbon nanotubes on thermo-mechanical properties of carbon fiber-reinforced polymer composites was investigated using dynamic mechanical thermal analysis in three different modes of deformation. Unsized carbon fiber (carbon fiber heat-treated to remove sizing agents)/epoxy composites were used as the reference to evaluate the enhancement due to coiled carbon nanotubes. Substantial improvements in viscoelastic properties of coiled carbon nanotube/carbon fiber/polymer composites over unsized carbon fiber/polymer composites were observed in all of the deformation modes. Coiled Carbon nanotube composites in shear mode exhibit highest enhancements in both storage as well as loss moduli due to superior mechanical interlocking between coiled carbon nanotubes and polymer matrix.