In order to investigate and compare the effects of RDX crystal quality on the safety and mechanical properties of pressed PBX, different RDX-based PBXs were prepared by a water suspension granulation method. The surface morphology, thermal decomposition properties, impact sensitivity, and mechanical properties of high-quality RDX (H-RDX) and PBX were characterized by SEM, optical microscope, DSC, impact sensitivity tester, and universal material testing machines. The results have shown that the H-RDX crystal has a smoother surface, regular shape, higher density, fewer defects, better thermal stability, and lower impact sensitivity than raw RDX. The activation energy of H-RDX-based PBX is 26.0% higher than that of raw RDX-based PBX, and H50 increased by 2.8 cm, indicating that the application of H-RDX to PBX can effectively improve its thermal stability and reduce the impact sensitivity in the safety performance. However, the compressive strength of pressed H-RDX-based PBX is 36% lower than that of pressed raw RDX-based PBX, showing that H-RDX results in the deterioration of the compressive strength of pressed PBX in mechanical performance. Fortunately, this study found a strategy on how to effectively improve mechanical performance, which is changing the type of binder and increasing the pressing pressure. Under the same pressing conditions, the order of compressive strength of PBX prepared by the three binders is FKM DS2603 > Viton A > PVAc. Moreover, the compressive strength of H-RDX-based PBX with FKM DS2603 can be increased by 33.7% compared with PVAc. When the pressing pressure is 200 MPa, the average compressive strength of H-RDX-based PBX with FKM DS2603 reaches 10.00 MPa, which can basically meet application requirements.
Keywords: compressive strength; high-quality RDX; impact sensitivity; mechanical performance; thermal decomposition performance.