Thermal decomposition behavior of silica-phenolic composite exposed to one-sided radiant heating

When polymer-matrix composite reaches sufficiently high temperature, pyrolysis reactions of the polymer matrix occur. The thermal decomposition behavior of silica-phenolic composite was investigated using solar radiant heating experiment with one-sided heat flux. Thermogravimetric studies and combined thermal analysis techniques were performed to characterize the thermal decomposition kinetics of phenolic resin. Simultaneously a thermal response model was used to calculate the through-thickness temperature distribution. The calculated time-dependent temperature profile at different material depths were compared with the experimental results measured at the same location. The silicaphenolic composite exhibited an excellent thermal insulation during thermal exposure. The postheating specimen was sectioned in millimeter segments to determine the density profile. On the basis of the density profile, the transition from char layer to pyrolysis zone to virgin material was estimated. Finally, the material morphology was analyzed for silica-phenolic composite after thermal exposure.