Influence of the Binder Structure on the Interfacial Adhesion and Antimigration Properties of the Propellant Charge

Maintaining the structural integrity of solid rocket propellant charges has been widely concerned by scholars around the world. The introduction of a polyester transition layer between the propellant and the liner is a new and effective method used to improve the interfacial bonding properties of the solid propellant charge and inhibit the migration of high-energy plasticizers. Uniaxial tensile pull-off specimens and accelerated aging experiments at multiple temperatures were used to study the interfacial bonding properties of propellant charges and the migration properties of plasticizers, respectively. The influence of the polyester structure on the two properties was also discussed in detail, and a targeted antimigration mechanism was proposed based on the molecular structure of the plasticizer. In addition, the Weibull model was used to fit the plasticizer migration behavior, and the plasticizer migration master curve in the charge system was obtained based on the principle of time-temperature superposition, which broadens the application field of the model and is important from an application perspective.

A Facile Way to Prolong Service Life of Double Base Propellant

The safe storage time for double base propellant (DBP or DB propellant) with stabilizers could usually be calculated to be greater than 40 years. However, the actual service life is far below that, which is largely caused by the decline of propellant mechanical performance. In this work polytetrafluoroethylene (PTFE) was introduced into the double base propellant formula as an additive. The tensile properties of this propellant before and after artificial aging were determined. The evaporation and diffusion characteristics of nitroglycerin (NG) in propellant were evaluated by thermogravimetry analysis (TGA). The results showed that mechanical properties of propellant were improved due to PTFE, especially for elongation at −40 °C, which was greatly increased by 115%. Moreover, the results of TGA showed that NG migration was reduced due to PTFE, which delayed the decline of propellant mechanical performance during aging. The reduction in elongation at −40 °C caused by aging was decreased by 68.5% for PTFE modified DBP. Enhanced mechanical properties and reduced NG migration could potentially prolong propellant service life.

Higher Performance and Safer Handling: Formulation Based on 2,2,2-Trinitroethyl Formate and Nitrocellulose

A new, green propellant formulation based on the high-energy dense oxidizer (HEDO) 2,2,2-trinitroethyl formate (TNEF) and nitrocellulose (NC) was prepared and thermally investigated using non-isothermal thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) was used to check the crystals of the oxidizer and the homogeneity of the new propellant formulation (NC-TNEF). The burning behavior of NC-TNEF was recorded by high-speed camera to observe the smoke produced. A high specific impulse (I_s =257.4 s) was obtained from the characteristics calculation of the new propellant formulation by using EXPLO5_V6.03 software. The NC-TNEF mixture did not show any endothermic peak and its exothermic peak was at 204.6 °C, which means that a composite might be formed. The activation energy of the NC-TNEF was in the range of 184-190 kJ mol^-1 . NC-TNEF has a higher performance and a lower hazard compared with the double-base propellant.