Study of carbon films from PAN/VGCF composites by gelation/crystallization from solution

A carbon film with a cross-sectional area much larger than that of a commercial carbon fiber (>6000 times) and a thickness of about 0.3 mm was obtained using a new method. In this method, composite materials of polyacrylonitrile (PAN) and vapor-grown carbon fiber (VGCF) prepared by gelation/crystallization from dilute solutions were used as starting materials The gelation/crystallization method was adopted to ensure high orientation of PAN chains. The composite materials were heat-treated at 200–300°C in an oxidizing atmosphere for thermal stabilization and then heat-treated to 1500°C in argon gas to promote carbonization. The tensile modulus and electric conductivity for the carbon materials with cross-sectional areas of about 0.6 mm2 (thickness 0.3 mm and width 2 mm) reached 18 GPa and 10 Ω−1 cm−1, respectively. The mechanical and electrical properties of the final carbonized materials were sensitive to the PAN/VGCF composition and the draw ratio. These phenomena were analyzed using Fourier transform IR and X-ray diffraction.