Applying modified hyperbranched polyester in hydroxyl‐terminated polyether/ammonium perchlorate/aluminium/cyclotrimethylenetrinitramine (HTPE/AP/Al/RDX) composite solid propellant

Abstract

Composite solid propellants demand fine and stable mechanical properties, creep resistance and stress relaxation performance during their long storage and usage time. In this study, modified hyperbranched polyester (MHBPE) was prepared and introduced into HTPE/AP/Al/RDX (HTPE, hydroxyl-terminated polyether; AP, ammonium perchlorate; RDX, cyclotrimethylenetrinitramine) solid propellant as an effective additive. The static tensile and dynamic mechanical properties of this propellant before and after the introduction of MHBPE were evaluated. The elevated interfacial interaction by using MHBPE between the binder and RDX fillers improved the toughness and elasticity of the propellant. The enhancement mechanisms were also confirmed by the influence on the fracture surface morphology of the binder which was investigated by SEM. In addition, some influence on the dynamic mechanical properties of HTPE/AP/Al/RDX propellant caused by MHBPE was investigated by dynamic mechanical analysis. The creep behaviors of the HTPE/AP/Al/RDX propellants with and without MHBPE were also investigated at different stresses and temperatures. Reduced creep strain rate and strain were obtained for the modified propellant, implying enhanced creep resistance performance. The creep properties were quantitatively evaluated using a six-element model and the long-term creep performance of the propellant was predicted using the time-temperature superposition principle. A creep behavior of nearly 10 6 s at 30°C could be acquired in a short-term experiment (800 s) at 30-70°C. Moreover, the stress relaxation investigation of the propellants with and without MHBPE at −40°C, 20°C and 70°C suggested that MHBPE/HTPE/AP/Al/ RDX propellant possessed better response ability to deformation. Thus, the application of MHBPE provides an efficient route of reinforcement to enhance the creep resistance and stress relaxation properties.

Interaction Mechanism of Composite Propellant Components under Heating Conditions

“…The thermal decomposition and combustion characteristics of propellants are closely related to the interactions between other components of the propellant [17]. Extensive research has been conducted on the thermal decomposition properties of AP [18,19], HTPB [20][21][22][23], HTPE [24], HTPB/AP propellant [25,26], and HTPE/AP propellant [16,27,28], laying an important foundation for understanding the thermal decomposition, ignition, and combustion characteristics of HTPB and HTPE propellants. However, similar research has not been conducted on the interaction between the propellant components during heating.…”

Application of Nano‐Sized RDX in CMDB Propellant with High Solid Content

“…RDX (cyclotrimethylenetrinitramine) is a kind of elemental energetic material synthesized in 1899, which developed rapidly during the Second World War. It has the advantages of high detonation velocity, high detonation heat, and stable detonation, which can meet the high energy requirements of mixed explosives and solid propellant [1][2][3][4][5][6][7]. However, ordinary RDX has high sensitivity and is easy to burn or explode when stimulated by the outside world, which limits its application.…”