Study on the influence of hollow glass microspheres structure on the ablation performance of EPDM rubber

Abstract The increasing demand for lightweight, ablation-resistant materials in solid rocket engines has promoted the application of hollow glass microspheres (HGM) owing to their low density and high thermal stability. In this study, the effects of different glass microspheres, including solid and hollow HS46 and HS38 microspheres, on the ablation and carbonization behavior of EPDM, PI/EPDM and PPTA/EPDM composites were evaluated using oxyacetylene tests and SEM. The results revealed that the addition of HGM decreased the ablation rates, with reductions of 13% for solid microspheres, HS46 by 3% and HS38 by 16% compared with HGM-free composites. The presence of organic fibers further reduced ablation rates. Solid microspheres exhibited the most pronounced effect due to their superior thermal stability, whereas hollow microspheres with larger diameters tended to increase ablation rates as a result of fragmentation. Notably, the combined addition of HGM and fibers such as PI and PPTA reduced ablation rates by 50%. These findings provide valuable guidance for the design of advanced aerospace insulation materials that are lightweight, thermally stable and exhibit enhanced ablation resistance.