Coal-tar pitches are used as matrix precursors of a wide range of carbon materials. Pitches are used as binders of different fillers (i.e. in electrodes and carbon brushes) and also to density carbon fiber preforms (i.e. in carbon/carbon composites). The transformation of a pitch into a carbon matrix requires thermal treatment (carbonization). The properties of the final material depend both on the chemical composition of the parent pitch and the experimental conditions in which carbonization is carried out. During pitch carbonization mesophase is developed. This stage is essential for the final properties of the pitch-based materials. In this work, a comparative study of mesophase development in pitches from different origins is presented. The set of pitches studied includes a commercial impregnating coal-tar pitch, isotropic pitches (air-blown pitches and the isotropic fractions of thermally treated coal-tar pitches isolated by pitch filtration) and partially anisotropic pitches (obtained by thermal treatment). A comparison of their different behavior in the first stages of carbonization is established and the results explained from the different chemical composition of the pitches.
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