Mechanism of the anisotropic nitroguanidine crystal arrangement on triple-base propellant failure by impact and strategy of structural enhancement

Nitroguanidine (NQ) in solvent-based triple-base propellants (STP) has a propensity to peel off and detach from the matrix, leading to significant defects, such as interface debonding within the propellant’s microstructure. This ultimately results in reduced and unstable mechanical properties. To address this critical issue, an efficient and eco-friendly manufacturing process was employed to successfully produce solventless triple-base propellants (SLTPs) as a comparison to conventional STPs. SLTP samples exhibit a mutually supportive three-dimensional spatial structure, with NQ crystals within the propellant matrix more securely bonded to the interface. They also demonstrate higher relative density (1.68 g·cm−3), more stable molding dimensions (no contraction), and enhanced tensile strength (41.92 MPa). Quasi-static structural failure tests reveal that the standard deviation of compressive strength for SLTP samples in three axes is smaller, registering at 1.10. The dynamic structural damage performance analysis indicates that the failure of energetic composite materials is attributable to separation fracture damage after the appearance of cracks on the tensile surface at −40 and 25 °C. Furthermore, the structural failure of these materials occurs due to significant collapse failure after the compression surface bends inward at 50 °C. Consequently, the present study offers a reliable theoretical foundation and procedural strategy for enhancing the structural strength of triple-base propellants.