Functionalization of Carbon Nanotubes into Materials with High Compressive Strengths
High-strength concrete is vital in most fixed protective structures and ceramics are likewise critical for the containment of blast fragments and bullet penetrators. Concrete and ceramics exhibit mechanically brittle behavior due to their microstructure. The utilization of carbon nanotubes as reinforcements for concrete and ceramic materials has been limited, in part, because of their inherent hydrophobic character. Typical approaches to increase the hydrophilic nature of carbon nanotubes include functionalization through oxidation and/or reaction with reactive species. Many of these techniques for CNT1/2s can result in degradation of sidewall integrity and reductions in mechanical, thermal, and electrical properties of the nanotubes. TRI-Austin has identified an approach that will address both the issues of matrix compatibility and improved adhesion of carbon nanotubes in inorganic matrix materials such as concrete and ceramics. This approach is based on the mechanisms of adhesion resulting from helical wrapping and covalent attachment of carbon nanotubes with inorganic macromolecules. TRI-Austin will be teaming with a leading producer of carbon nanotubes that has multiple pilot plants and commercial demonstration units for the production of nanotubes. CNT1/2s have the potential to increase the mechanical properties, including fracture toughness, of inorganic composites by inducing fiber pull-out and bridging, interfacial debonding, crack deflection and pinning effects during fracture . These improvements will potentially affect the ability to design lighter weight structural concretes and ballistic armors.