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Updated: Aug 29, 2025
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Laboratory Scale Slow Cook-Off Testing of Rocket Propellants: The Combustion Rate Analysis of a Slowly Heated Propellant CRASH-P Test
Published on: February 6, 2021
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Comparative Study on Thermal Response Mechanism of Two Binders during Slow Cook-Off
Xinzhou Wu1, Jun Li2, Hui Ren1
1State Key Laboratory of Explosion of Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
Polymers
|September 9, 2022
Summary
Hydroxyl-terminated polyether (HTPE) propellant ignites at a lower temperature and undergoes combustion, unlike hydroxyl-terminated polybutadiene (HTPB) propellant which explodes. HTPE
Area of Science:
- Materials Science
- Chemical Engineering
- Propulsion Technology
Background:
- Solid propellants are crucial for rocket and missile systems.
- Understanding thermal stability and cook-off behavior is vital for safety and performance.
- Hydroxyl-terminated polybutadiene (HTPB) is a common binder, but alternatives are sought.
Purpose of the Study:
- To investigate the superior slow cook-off performance of hydroxyl-terminated polyether (HTPE) propellant compared to HTPB propellant.
- To elucidate the underlying thermal response mechanisms of HTPE and HTPB binders.
- To identify the microstructural factors contributing to enhanced safety in HTPE propellants.
Main Methods:
- Slow cook-off tests comparing HTPE and HTPB propellants.
- Thermal analysis techniques including Thermogravimetric Analysis (TG) and Scanning Electron Microscopy (SEM).
- Infrared spectroscopy to analyze chemical changes.
- Box counting method for quantitative defect analysis.
- Mechanical property testing and gel fraction analysis.
Main Results:
- HTPE propellant exhibited a significantly lower ignition temperature (150 °C) than HTPB propellant (240 °C).
- HTPE propellant underwent combustion, while HTPB propellant showed explosive behavior during cook-off.
- HTPE binder melted above 120 °C, forming a "high-temperature self-repair body" that filled cracks.
- AP decomposition at lower temperatures created defects, which HTPE effectively mitigated through melting and dispersion.
Conclusions:
- The distinct thermal response mechanisms of HTPE and HTPB binders are the primary reason for the observed differences in slow cook-off behavior.
- HTPE's ability to form a self-repairing structure upon heating contributes to its superior safety and performance under thermal stress.
- This study reveals the microscopic mechanism behind HTPE's enhanced slow cook-off performance over HTPB.
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