Assembly Strategies for Fully Aligned and Dispersed Morphology Controlled Carbon Nanotube Reinforced Composites Grown in Net-Shape

Abstract

Long carbon fibre polymer composites represent the state-of-the-art materials technology for high performance weight driven structures, such as airframes. Although a significant amount of optimisation remains to be done to fully exploit the benefits of long fibre composites, these materials are relatively speaking still very crude, when compared to what nature has achieved with wood or bone for example. Nanomaterials, and specifically carbon nanotubes (CNTs), have teased with their spectacular mechanical and physical properties in isolation. These headline properties have prompted much work into the manufacturing of composite materials using CNTs as reinforcements, but thus far, successful exploitation of these impressive properties has been modest. A gap remains before these materials represent a real competition to long carbon fibre composites, even though fairly modest applications such as CNTs as fillers for matrix toughening and imparting electrical functionality are showing some promise. In this paper a critique is made of various reinforcement approaches through the lens of ’nano-augmented, ’nano-engineered’ and ’nano-enabled’ categories as defined by Airbus. These approaches are compared to an analysis of nature’s ’baseline’. A new ’nano-enabled’ strategy for the growth of fully aligned and dispersed bulk CNT composite materials and structures, allowing for simultaneous multi-scalar morphological and topological optimisation, is described. This new strategy, analogous to nature’s approach, consists of the vapour phase growth of aligned forests of carbon nanotubes coupled to the environment of Additive Layer Manufacturing (ALM). Early feasibility results are presented and currently identified challenges to successful scale-up are discussed.