Multifunctional Prepregs and Laminated Composites Made by Shear Pressing Carbon Nanotube Arrays

A novel method of fabricating carbon nanotube (CNT) reinforced polymer matrix composites is proposed. It includes growing super-aligned carbon nanotube arrays on a flat substrate, using NCSU proprietary shear pressing method to compress the grown arrays into a layer of densely packed, highly aligned CNTs inclined at an angle of several degrees to the substrate, separating the produced CNT sheet from the substrate, infusing polymeric resin into the sheet to fabricate an uncured prepreg, laying up the prepreg plies at desired orientations, and finally curing the laminate. This manufacturing process will result in a thick, high CNT volume fraction reinforced laminate with unique in-plane and out-of-plane reinforcement architectures. This kind of laminates can be used for relatively small size aerospace structures, where special combinations of high mechanical strength, high electrical conductivity and high thermal conductivity are required. Experimental validation and scaling up this technological approach will include increasing CNT length and their array growth area, building computer controlled apparatus for precise shear pressing of the grown arrays, developing special means for aerospace grade resin infusion into CNT sheets, ply lamination and cure. Initial experimental studies will include in-plane tensile testing and measurements of through thickness electrical and thermal conductivities. BENEFIT: Aerospace industry may be primarily interested in using these novel CNT reinforced prepregs and composite laminates for unique structures which require low weight and high strength combined with high electrical and/or high thermal conductivity. Immediate applications may include light-weight composite structures for housing various aircraft electronic systems. Currently available composite laminates are not applicable due to their low through-thickness thermal and electrical conductivities. In the proposed CNT prepregs and laminates, with long CNTs extending through the whole ply thickness, these properties will be elevated to a much higher level, at least an order of magnitude. The development of integrated manufacturing cycle for these materials and their structural components will enable to supplying them in large volumes for the next generation unmanned aircraft and surveillance platform structures, as well as for the future civil transport systems.