Phenolic resin char-formation during hyperthermal ablation

Abstract

Ablation is a self-regulating heat and mass transfer process in which incident thermal energy is expended by sacrificial loss of material 1 1 ASTM (E 349)30. . The surface of a carbonaceous char is lost during the ablation of fiber-reinforced phenolic resin composites. The transient high temperatures penetrate deeply, resulting in an underlying pyrolysis zone with rapid pyrolysis rates and a high char interface temperature. Phenolic resin char-formation at high heating rates and high temperatures was studied using thermogravimetry (TG). The specialized thermobalance permitted runs in helium at rates of 3–430°C/min up to 1400°C. Computer code analysis provided rate parameters for an Arrhenius type correlation. The parameters represented well the parent TG run but were not independent of heating rate. A complex correlation was considered necessary for universal use. The attractive alternative was parameter evaluation at high heating rates using TG.