Evaluation of Thermal and Mechanical Properties of Phenolic Resins used as Matrix in Thermal Ablative Nozzles

Phenolic resins such as novolac and resol are widely used in the manufacture of ablative materials. In this study an investigation on thermal resistance and mechanical properties of these resins and their resultant composites has been done. TGA analysis reveals a significant thermal degradation of novolac started at 420 °C and showed a maximum at 480°C. These were 380 °C and 520 °C for resol respectively.The results of flexural tests showed that novolac-based composites with a strength at break of 148 MPa had a superior mechanical properties than their resol counterparts with a strength of 101 MPa. Also the results of oxyacetelene torch test indicated novolac-based specimen had better thermal shock resistance.