Exploring composites based on PPO blend as ablative thermal protection systems – Part II: The role of equiaxial fillers

Similarly to the activity described in Part I, the PPO-based composites were studied in view of their pre-screening as potential candidates in innovative ablative shields. In this case equiaxial, oxide and non-oxide powders, precisely magnesium aluminate spinel, aluminum hydroxide (boehmite), δ- and α-alumina, silicon carbide, silicon nitride and molybdenum disilicide, were used as fillers. Nanometric and micrometric α-alumina and silicon carbide powders were exploited to investigate the effect of the particle size. The alumina-based composites presented the most promising behavior. On the other hand, molybdenum disilicide implied a significant decrease in thermal stability and combustion time.