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Hydroxyl-terminated polyether (HTPE) propellant and HTPE/Poly(ε-caprolactone) (PCL) propellant were compared to explore the effects of introducing PCL to HTPE propellant on the mechanical and thermal properties at the wide temperature range of − 50 °C to 70 °C. The energetic properties of HTPE and HTPE/PCL propellants were also evaluated, the ideal specific impulse and density of HTPE/PCL propellant were found to be slightly enhanced comparing with those of HTPE propellant. The tensile mechanical properties results revealed that the introduction of PCL could improve the maximum tensile strength (σm) of HTPE/PCL propellant at the wide temperature range of − 50 °C to 70 °C, its σm increased from 0.38 to 0.75 MPa at 20 °C, 0.25 to 0.48 MPa at 70 °C and 4.01 to 4.77 MPa at − 50 °C separately comparing with those of HTPE propellant. The thermal decomposition behavior at 0.1 MPa showed that the introduction of PCL could promote RDX and AP in HTPE/PCL propellant to decompose. Bu-NENA was hardly to evaporate from HTPE/PCL propellant at higher pressure, which was beneficial to its thermal decomposition. The introduction of PCL could be more effective to inhibit the evaporation of Bu-NENA from HTPE/PCL propellant at 0.1 MPa, the activation energy of evaporation of HTPE and HTPE/PCL propellants was 53.66 kJ mol−1 and 77.90 kJ mol−1, respectively. [ABSTRACT FROM AUTHOR]

A series of cross-linked hydroxyl-terminated polyether and poly(ε-caprolactone) HTPE/PCL binders were prepared by varying the relative mass contents of PCL to HTPE. The correlations between the microstructures and macroscopic mechanical properties of HTPE/PCL binders at a wide temperature range of − 50 to 70 °C were investigated. The cross-linking network structures of HTPE/PCL binders were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and low-field nuclear magnetic resonance (LF-NMR), and the universal testing machine was used to characterize the mechanical properties of HTPE/PCL binders. It is found that the influence of adding PCL on the physical cross-linking network structures is not obvious, but it reduces the degree of microphase separation. For the chemical cross-linking network structures of HTPE/PCL binders, the cross-linking density (Ve) demonstrates an increasing tendency with enhancing PCL mass content, but the molecular weight between the cross-linking points (Mc) shows an opposite change trend. The addition of PCL can improve the maximum tensile strength (σm) of HTPE/PCL binders under the wide temperature range of − 50 to 70 °C. The HTPE/PCL binder with 40 wt% PCL possesses the better mechanical properties; its σm increases from 0.63 to 0.81 MPa at 20 °C, 1.64 to 3.06 MPa at − 50 °C and 0.57 to 0.68 MPa at 70 °C separately comparing with the HTPE binder. [ABSTRACT FROM AUTHOR]