Synthesis of multifunctional additives for solid propellants: Structure, properties and mechanism

To simplify the composite propellant formulation and address the current issue of the single-functionality present in existing additives, the multi-cyano, amine-based polybutadiene (AEHTPB-CN) was prepared based on AEHTPB by adopting appropriate synthesis strategies. By replacing 10% of HTPB binder in the propellant formulation, it can effectively enhance the interfacial bond strength between the propellant binder matrix and solid fillers (AP (ammonium perchlorate) and RDX (cyclotrimethylene-trinitramine)), the mechanical properties of the HTPB/AP/RDX/Al propellant were superior to blank control propellant with an improvement of 35.4% in tensile strength, 62.0% enhancement in elongation at break, and reduce the propellant burn rate by 10.7% with any energy loss. The function mechanism of AEHTPB-CN was systematically elucidated through experiments and computer simulation techniques. The results show that the tertiary amine group in AEHTPB-CN can react with AP to form ammonium ionic bonds, and the hydroxyl and cyano groups can form hydrogen bonding interactions with AP, which enables AEHTPB-CN to be firmly adsorbed on the AP surface through chemical and physical interactions. For RDX, the interfacial bonding effect of AEHTPB-CN is attributed to their ability to form C–H⋅⋅⋅NC weak hydrogen bonding interaction between the cyano group and RDX methylene group.