Biobased Carbon Fibers and Thermosetting Resins for Use in DoD Composites Applications

Current constituent materials used to produce composites for the military are often made from both fibers and resins that are derived from petrochemical feed stocks. The use of biological resources to make advanced fibers and high-performance thermosetting resins will help reduce the dependence of military composites on the volatile cost of petroleum, result insignificant technological gains, and reduce toxicity of composite materials. We have used both bacterial and chemical decomposition of lignin to make tractable structures that are capable of fiber spinning. Efforts to stabilize and carbonize lignin have resulted in the highest-performing lignin-based carbon fibers to date. However, new developments in commercial polyacrylonitrile-carbon fiber technology have eliminated the need for lignin-based carbon fibers altogether. Unsaturated polyester, vinyl ester, epoxy, and polyurethane resin thermosets have been developed. Isosorbide-based vinyl ester resins have the highest-ever glass transition temperatures for a vinyl ester system. Bisguaiacol F has very promising properties as are placement for bisphenol A with significantly reduced toxicity. Furan epoxies have shown high promise with good thermal properties and excellent toughness. Many of these resin systems have low costs and even lower life cycle costs relative to commercial resins, and thus they have good potential for transition to commercial industry.