Thermo-oxidative aging behavior of high-cis1,4-hydroxyl-terminated polybutadiene

This study investigates the thermo-oxidative aging behavior of high-cis hydroxyl-terminated polybutadiene (cis-HTPB, cis-1,4 content > 90%) through integrated multi-scale experiments and molecular simulations. Experimental results demonstrate that cis-HTPB significantly outperforms traditional HTPB (I-HTPB) in terms of inhibiting oxidative chain scission, maintaining structural stability, and delaying the degradation of mechanical properties. The simulation results further reveal the molecular-level reasons for the performance advantages: the cis-1,4 structure enhances chain flexibility and free volume, facilitating the uniform diffusion of oxygen and free radicals, effectively suppressing local oxidation, and delaying crosslink network formation. In contrast, I-HTPB, due to its highly reactive 1,2-vinyl structure and limited free volume, initiates intense surface-dominated radical chain reactions. These findings establish that cis-HTPB improves binder aging resistance by modulating oxygen diffusion pathways and radical reaction sites, thereby providing a theoretical foundation for the development of long-life solid propellants for deep-space missions.