Mechanisms of the pyrolysis of phenolic resin in a carbon/phenolic composite

The pyrolysis of carbon/phenolic composites is a critical step in the manufacture of high temperature carbon/carbon components. Understanding the reaction kinetics of the pyrolysis reactions is essential for advancement in the processing of carbon/carbon materials. To increase the understanding of the reaction kinetics, Fourier transform infrared spectroscopy (FTIR) and gas product evolution analysis have been used to investigate the pyrolysis reactions of a carbon/phenolic composite system. Published mechanisms for pyrolysis of neat phenolic resin are evaluated to clarify discrepancies that exist between mechanisms and determine their applicability to a composite system. A mechanism for the pyrolysis of carbon/phenolic composites is proposed, which describes the resin pyrolysis reaction as occurring in three major reaction regions: formation of additional crosslinks, breaking of the crosslinks, and stripping of the aromatic rings.