Interfacial improvement of carbon fiber/epoxy composites by using electrospray carbon nanotube deposition

Carbon nanotubes (CNTs) were coated on unsized carbon fibers using the electrospray deposition method. The overall depositing process resulted in a multi-scale CNThybridized structure compared to the original primary carbon fibers. The wetting behavior between fibers and epoxy resin was tested using contact angle measurements for drop-on-fiber systems and indicated good wettability. Single fiber fragmentation tests were conducted on hierarchical fiber/epoxy model composites, demonstrating a significant (~45%) improvement of the apparent interfacial shear strength (IFSS) over the baseline composites. The result is associated with improved stress transfer between the carbon fibers and surrounding matrix through the coated CNT layer.