Unraveling the ablative behavior through the design of a POSS-Benzoxazine/EPDM network under harsh environments.

• A novel EPDM ablation resistance composite was designed by integrating benzoxazine fine-tuned with octal (propyl glycidyl ether) polyhedral oligomeric silsesquioxane (BA-POSS) into the network structure of EPDM. • The EPDM/BAP18 composite in this study aims to strike a balance among these three key performance parameters (ablation rate, tensile strength, and elongation at break) of the insulation layer while maintaining a low density. • The structural evolution of EPDM composites during pyrolysis was studied through SEM, EDS, TG-IR and XPS, etc., in order to further understand the improvement of ablation resistance exhibited by EPDM composites. In order to meet the demands of the insulation layer in the swiftly advancing aerospace thermal protection system and enhance the ablation resistance of ethylene propylene diene rubber (EPDM) insulation layer, a novel EPDM ablation resistance composite was designed by integrating benzoxazine fine-tuned with octal (propyl glycidyl ether) polyhedral oligomeric silsesquioxane (BA-POSS) into the network structure of EPDM. The resulting composite exhibited a more densely cross-linked EPDM/BA-POSS network, consequently augmenting both the mechanical and ablation properties of the EPDM ablation resistance composite. The cross-linking density and tensile strength of EPDM/BA-POSS composite with 18 phr (parts per hundred rubber) BA-POSS increased by 78.4% and 30.7%, respectively, and the linear ablation rate significantly reduced by 47.7%, compared with EPDM composite without BA-POSS. Additionally, the ablation mechanism of EPDM/BA-POSS composites was elucidated through an investigation of the thermo-chemical transformation and analysis of the ablated carbon layer. This study contributes novel insights and methodologies for the future design of low-density rocket motor insulation compounds that offer cost efficiency, enhanced functionality, and wider applicability. [ABSTRACT FROM AUTHOR]