9623818 Jacobsen This Small Business Innovation Research Phase II project will refine the CVD processing window for beaded fiber, and develop the window for crenulation free fiber. The resulting products will be used to fabricate various composites, which will then be tested relative to their normal crenulated fiber counterparts. Crenulation-free fiber is expected to impart improved and more reliable thermal and electrical transport properties to its composites. The beaded morphology is expected to give composites improved mechanical reinforcement, with reduced crack propagation, and greater flexibility in matrix choice due to its ability to physically interlock, rather than chemically bond, with a matrix. This research effort seeks to define manufacturing process variables for the control of vapor-grown carbon fiber (VGCF) morphology. Previous efforts demonstrated that the properties of individual fibers depend on the degree to which they exhibit a morphological feature called crenulation. Further, it has been shown that the severity of crenulation can be increased by certain modifications in the manufacturing process. In the extreme, mild crenulations give way to a novel morphology with well-defined beads, scattered along the fiber's length. The VGCF morphologies under development would mechanically reinforce composites, and provide improved thermal and electrical properties. Such composites would be employed in the automotive and aerospace industries, where their low densities give them a very high weight adjusted figure of merit. They would also be used in the electronics industry. The fiber is also being studied specifically for use in low-friction bearings, and as a reinforcement to tire rubber.
