Carbon fibres: structure and mechanical properties

Abstract The microstructure of six types of acrylic-based and hydrated cellulose-based carbon fibres of strengths from 1650 to 6120 MPa and elastic moduli from 97 to 228 GPa were studied by scanning electron microscopy (SEM). A ‘microcomposite’ structure of carbon fibres studied consisting of quasi-amorphous (‘matrix’) and orientated fibrillar carbon was revealed. This led to a new model of the fibre structure. The analysis of results of testing different carbon fibres defines the elastic modulus of ‘matrix’ carbon, and shows plastic drawing of fibrils. The model describes the properties of fibres and predicts ways to improve the fibre properties.