High-performance thermoplastic solid propellants via mechanochemical functionalization

Thermoplastic composite solid propellants, a new type of solid propellant that do not require chemical curing, have attracted increasing attention due to their unique R 3 (Recover, Reuse, and Recycle) characteristics. However, the absence of a chemically crosslinked three-dimensional macromolecular network results in relatively poor mechanical properties, particularly low elongation, which significantly limits their practical applications. In this work, a mechanochemically mediated small-molecule modification strategy was proposed. Three functionalized small molecules (MAH, MAN, and MABE) were synthesized, and subsequently grafted onto EVA (ethylene vinyl acetate) thermoplastic elastomers under amine-borane mediated mechanochemical conditions to achieve functional modification. The results showed that compared with unmodified EVA, the mechanical properties of EVA-based thermoplastic adhesives and propellants are significantly improved after mechanochemical modification, and the AP dewetting phenomenon in the propellant is markedly reduced. Among them, MABE, containing boronate ester groups, demonstrates the most pronounced improvement. While maintaining the processing performance and thermal behavior, the mechanical properties of the propellants could achieve 0.63 MPa/22.3% (25 °C) and 4.55 MPa/13.5% (–40 °C), respectively. Further study suggested that mechanochemistry-engineered EVA featured a pronounced decrease in γ SL accompanied by a significant increase in W a , indicating enhanced wetting and strengthened interfacial interactions with AP.