Effect of Plasticizer on Mechanical and Thermal Properties of In Situ-Prepared Block Hydroxyl-Terminated Polyether Applied in Propellants

The relationship between the mechanical properties of in situ-prepared hydroxyl-terminated polyether (HTPE)/ N -butyl- N -(2-nitroxyethyl)nitramine (Bu-NENA) binders and the plasticization ratio ( pl / po ), ranging from 0.4 to 1.2, was studied. The thermal properties and the very early stage of evaporation of Bu-NENA from an HTPE/Bu-NENA binder with a pl / po of 1.0 were also investigated. The results revealed that the pl / po ratio has a strong influence on the mechanical properties. When the pl / po ratio was 1.0, the mechanical properties of the in situ-prepared HTPE/Bu-NENA binder were satisfactory. The results showed that the T g values of the in situ-prepared and traditional HTPE/Bu-NENA binder decreased as the plasticization ratio increased, and finally stabilized at approximately −75 and −78°C, respectively; moreover, the degree of phase mixing of the two soft segments of the in situ-prepared HTPE/Bu-NENA binder was greater than that of the traditional HTPE/Bu-NENA binder. The activation energy of the Bu-NENA evaporation from the in situ-prepared HTPE/Bu-NENA binder was close to that for the traditional HTPE/Bu-NENA binder, but the pre-exponential factor differed by an order of magnitude. Compared with the traditional HTPE propellant, the mechanical properties of the in situ-prepared HTPE propellant were greatly improved.