Application on epoxidized hydroxyl terminated polybutadiene in liner and its effect on liner properties

To investigate the application of epoxidized hydroxyl-terminated polybutadiene (EHTPB) in the liner of solid rocket motors and its effect on properties of liner, experimental characterization and molecular simulation were combined to systematically evaluate the mechanical properties, curing behavior, interfacial adhesion performance, and nitrate migration resistance of EHTPB-based liners. The results indicate that replacing hydroxyl-terminated polybutadiene (HTPB) with EHTPB effectively reduces the curing reaction activation energy, accelerates the curing rate, and enhances the intrinsic mechanical strength of the liner. The EHTPB liner exhibits good interfacial adhesion with NEPE propellant, showing tensile and peel strengths of 1.14 MPa and 2.45 N·mm⁻¹, respectively. However, nitrate migration tests and molecular dynamics simulations reveal that the nitrate migration resistance of EHTPB liners decreases, with the migrated contents of NG and BTTN increasing to 2.99% and 2.46%, respectively. The introduction of epoxy groups improves the reactivity with isocyanates, while simultaneously increasing the diffusion coefficient of nitrate esters in the liner.