STRUCTURAL COMPOSITES

High performance carbon fibers are used in structural composites in a wide range of applications including aerospace, automotives, and sporting equipment. Recently, it has been shown that adding a customized grade of Unidym's nanotubes to the polymer precursor of the fibers can substantially improve the resulting fibers. The CNTs act as a nucleating agent for polymer crystallization thereby providing a template that improves the polymer orientation. Specifically, a group at Georgia Tech has shown that incorporation of 1 wt % of Unidym XO grade nanotubes into polyacrylonitrile (PAN) precursors increased the tensile strength and modulus of the resulting carbon fiber by 64% and 49%, respectively. [H. G. Chae, M. L. Minus, A. Rasheed, S. Kumar, Polymer 48, 3781 (2007)]. Efforts are underway to develop this technology for commercialization of a new generation of carbon fibers.

In addition to forming the basis for a new generation of carbon fibers to be used in composites, carbon nanotubes can be dispersed in polymers and epoxies to improve the compression, shear, and bending properties of composites, including stiffness, toughness, fatigue life, failure mechanisms and wear properties. For example, nanotubes can be used to improve the modulus and toughness of elastomers. Nanotubes have also been shown to improve several mechanical properties by several tens of percents in a wide variety of thermoset composite systems at loading levels of one percent or less. One Unidym customer, for example, demonstrated a 35% improvement in the bending strength of a ten-ply fiberglass lay-up with a nanotube loading of only 0.1 weight % per ply.