Carbon-carbon composites made with oxidised PAN (Panex) fibers

Carbon-carbon composites have been developed using Panex fibers (oxidised PAN fibers) possessing varying amounts of surface groups as reinforcement and phenolic resin and coal tar pitch as matrix precursors. Pyrolysis behaviour of resin based composites exhibited cross-sectional shrinkage and weight loss varying from 18 to 24% and from 32 to 40%, respectively, depending upon the amount of surface groups present on the surface of the Panex fibers. The flexural strength and flexural modulus of resin based composites (HTT 1000 °C) were in the range of 11.0–30 MPa and 30.0–50 GPa, respectively, whereas for coal tar pitch based composites the values were 35–55 MPa and 30–50 GPa. On graphitisation (HTT 2700 °C) there is very little improvement in the values of mechanical properties in case of resin based composites (the composites became fragile to handle) but the values increased to 4–6-fold (flexural strength, 200–250 MPa) and 2–3-fold (flexural modulus, 100–120 GPa) in the case of coal tar pitch based composites. It is possible to develop carbon-carbon composites with Panex fibers having mechanical properties equivalent to those developed with commercial carbon fibers (T-300 by Toray).