Carbon fiber reinforced carbon aerogel composites for thermal insulation prepared by soft reinforcement

To overcome the brittleness and the pyrolysis shrinkage of carbon aerogels, carbon fiber reinforced composites were prepared by copyrolysis of polyacrylonitrile fiber reinforced resorcinol-formaldehyde aerogel composites (PAN/RFs). The PAN/RFs were obtained by impregnating the PAN fiber felt with RF sol and then supercritical drying. Upon carbonization the PAN fiber shrinks with the RF aerogel, thus reducing the shrinkage differences between the fiber and the aerogel, and results in crack-free carbon fiber reinforced carbon aerogel composites, with a thermal conductivity of 0.073 W/m K at 25 degrees C in air. Our new method may greatly expand the usage of carbon aerogels in general applications. (C) 2011 Elsevier B.V. All rights reserved.