Fire protective performance of intumescent paint and ablative elastomer used for high pressure hydrogen composite cylinder

The thermal degradation of epoxy resin/carbon fiber composites have been experimentally studied in ISO 5660 standard cone calorimeter. The influence of external heat fluxes on the reaction-to-fire properties of composite laminate is identified. Mass loss, time-to-ignition, specific mass loss rate, thermal response parameter and gasification heat were systematically measured and calculated. The four principal steps of the thermal degradation process of virgin composite are also analyzed and identified. In order to improve the reaction to fire of the composite for a safe hydrogen cylinder application, two insulating coatings (constituted by an intumescent paint or an ablative elastomer) have been applied on the exposure surface of composite. As a result, the thermal properties of composite (mass loss, time-to-ignition, SMLR peak amplitude and temperature at coating/composite interface) are improved significantly. Furthermore, the ablative elastomer represents a better fire protective performance than the intumescent paint one at low temperature. However, at high temperature conditions, the ablative layer is thermally broken and flaked away from the composite substrate, and so loses its protective performance. At low heat flux the intumescent paint shows slightly worse protective performance which becomes better than the ablative material at high heat flux conditions due to its very good bonding capacity to the composite surface.