Y. Martinez Rubi, M.B. Jakubinek, B. Ashrafi, B. Simard, C.T. Kingston, G. Palumbo, J. McCrea, R. Pallotta, H. Katugaha
National Research Council Canada,
Keywords: nanotubes, nanocomposites, fabric, multifunctional materials, manufacturing
Summary:Carbon nanotubes (CNTs) have long been considered promising for development of advanced composite materials, due to their unsurpassed properties along with low density, and they are now appearing in an increasing number of industrial applications from sporting goods to aerospace. Integration of nanotubes in the form of fabrics or other preformed assemblies (sheets, films, fibers, etc.) simplifies their handling and allows for higher nanotube content, which is needed to better leverage their properties in advanced composite materials. Yarns and sheets formed from long, aligned CNTs have yielded the highest properties for macroscale CNT materials and nanocomposites; however, such CNTs materials are not yet broadly available. We have developed scalable methods for production of non-woven nanotube-polyurethane fabrics made from broadly available, low-cost, industrial-grade nanotubes based on a dispersion and filtration method. In this approach, control of a solvent/non-solvent system results in controlled adsorption of polyurethane on the nanotube surface leading to recovery of a nonwoven fabric of polyurethane-coated nanotubes. The method provides for tailoring of the nanotube:polymer ratio and control of the density/porosity of the nonwoven nanocomposite fabrics. The resulting prepreg-like fabrics can be handled and employed analogously to other fabric and prepreg materials and have been layered, laminated or infused to produce thick nanocomposites, or integrated with conventional composites, for a series of multifunctional composites demonstrations (e.g., electromagnetic shielding, heating, flame resistance). Recently, in response to an Innovative Solutions Canada Challenge for manufacturing of nanocomposite fabrics, continuous production of these carbon nanotube-polyurethane fabrics was achieved by Integran Technologies. The continuous method translates the approach to a spray process onto a carrier film while achieving similar properties and compositional control as in the batch filtration process. The new method is enabling both larger-scale, continuous fabric production – an essential step for industrial application – as well as direct deposition onto other substrates and production of other high-nanomaterial content nanocomposites.