Well-aligned NiCoS nanowires, synthesized hydrothermally on the surface of woven Kevlar fiber (WKF), were used to fabricate composites with reduced graphene oxide (rGO) dispersed in polyester resin (PES) by means of vacuum-assisted resin transfer molding. The NiCoS nanowires were synthesized with three precursor concentrations. Nanowire growth was characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Hierarchical and high growth density of the nanowires led to exceptional mechanical properties of the composites. Compared with bare WKF/PES, the tensile strength and absorbed impact energy were enhanced by 96.2% and 92.3%, respectively, for WKF/NiCoS/rGO (1.5%)/PES. The synergistic effect of NiCoS nanowires and rGO in the fabricated composites improved the electrical conductivity of insulating WKF/PES composites, reducing the resistance to ∼10 Ω. Joule heating performance depended strongly on the precursor concentration of the nanowires and the presence of rGO in the composite. A maximum surface temperature of 163 °C was obtained under low-voltage (5 V) application. The Joule heating performance of the composites was demonstrated in a surface deicing experiment; we observed that 17 g of ice melted from the surface of the composite in 14 min under an applied voltage of 5 V at -28 °C. The excellent performance of WKF/NiCoS/rGO/PES composites shows great potential for aerospace structural applications requiring outstanding mechanical properties and Joule heating capability for deicing of surfaces.

No abstract

This paper presents a study on incorporation of carbon nanotubes (CNTs) in fiber-reinforced plastics for real-time structural health monitoring. CNTs dispersed in a solvent were uniformly spray-coated on the surfaces of glass fiber fabrics, which were then layed-up and impregnated with an unsaturated polyester resin using vacuum-assisted resin transfer molding to form composite samples. Prior to resin infusion, electrodes were embedded on the periphery as well as between the plies for electrical resistance monitoring. The composite sample was subjected to three-point bending, during which the changes in resistances between various electrode pairs were measured and recorded. Experimental results revealed the dependence of resistance change on the loading conditions, amount of CNTs coated, measured directions, and presence of structural failure. In particular, the percolated CNT networks enabled real-time identification of various failure modes, including delamination, fiber breakage, and in-plane compression. The proof-of-concept was demonstrated by fabricating and testing with a scaled-down wind turbine blade.

No abstract

No abstract