The Volumetric Coefficient of Thermal Expansion of PBX 9502
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
TATB (1,3,5-triamino-2,4,6-trinitrobenzene) is an insensitive high explosive (IHE) used in plastic-bonded explosives (PBXs) such as PBX 9502. TATB’s plate-like crystals have highly anisotropic coefficient of thermal expansion (CTE) values, where the through-plane direction grows about twice as much as the in-plane directions. Compactions of TATB have preferred alignment of crystals, with resulting CTE anisotropy. Additionally, TATB-based compactions exhibit anisotropic irreversible volume expansion (ratchet growth) when thermal cycled to temperatures away from ambient. From a series of measurements on a thermal mechanical analyzer (TMA), the initial thermal ramps away from ambient were used to estimate the volumetric coefficient of thermal expansion of PBX 9502. The TMA measures the change in axial strain of the material as a function of temperature. Starting at ambient, thermal ramps of 1°C per minute were conducted to various endpoint temperatures from -43°C to 173°C on specimens machined from isostatically-pressed hemispheres of PBX 9502. Anisotropy was measured and the volumetric CTE estimated over this temperature range. For ease of use by experimentalists, a 5th-order polynomial was fit to the calculated change in density as a function of temperature. The CTE of neat TATB, PBX 9502, and the Kel-F binder were compared over the given temperature range. At lower temperatures, TATB expands more than PBX 9502 until the melt temperature of Kel-F (80°C), above which the two exhibit similar CTE values.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1425787
- Report Number(s):
- LA-UR-18-22138
- Country of Publication:
- United States
- Language:
- English
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