Carbon/carbon composites based on a polyimide matrix with coal tar pitch

Blending of coal tar pitch with a polyimide precursor based on acetyl derivatives of aromatic diamines during its synthesis leads to a homogeneous, highly thermostable matrix for carbon fibre reinforced composites. If the weight content of the pitch in the polyimide matrix does not exceed 40%, the mechanical properties (flexural strength, shear modulus and fracture toughness) of these composites are comparable to those of similar composites based on a pure polyimide matrix. Carbonisation and graphitisation of the composites with a properly blended matrix precursor leads to carbon fibre reinforced carbon composites with lower open porosity and higher density, elastic modulus and flexural strength than those of composites based on a pure polyimide matrix. (C) 2002 Elsevier Science Ltd. All rights reserved.