Date of Award
Master of Science in Chemistry
Jimmie C. Oxley
James L. Smith
An accurate small-scale (gram) test that predicts large-scale (kg) explosivity is crucial for organizations to make accurate informed decisions when creating regulations, safety, and transportation guidelines. There have been several lab-based tests developed to provide information on whether a new substance has explosive potential, but they fail to consider how energetic materials behave on the large-scale. The concern is many non-ideal explosives, such as fuel oxidizer mixtures, have failure radii that are larger than the 48 mm diameter tube used in the United Nation (UN) test series. In addition, the UN test series uses at least 1.3 kgs of material, requiring production of significant amount of material.
A novel small-scale explosive testing method using a ½” diameter rate stick, overdriven booster, and RDX seeding was employed. The detonation behavior of the subject material was filmed and analyzed using a Specialised Imaging SIMD-16 high speed framing camera and Optronis Optoscope Streak camera. By analyzing the streak images with an in-house computer script the slope of the streak record was determined, giving the detonation velocity of the booster, the run distance required for the material to achieve a steady state detonation, the detonation velocity of the test material, decay velocity of the shock wave in a detonation failure, and the total distance the shock wave travelled. In addition, materials were analyzed by differential scanning calorimetry (DSC) to observe heat release.
Thermal and shock techniques were used to assess the hazards of 8 fuel-oxidizer mixtures and 7 select organics. The formulations which detonated without added RDX exhibited greater than 3000 J/g heat release at temperatures below 450oC. When DSC is coupled with ½” rate stick detonation testing, a definitive tool for hazard evaluations was discovered.
The small-scale tests were evaluated at three levels of sophistication. The first test used shock front tracking to extend small-scale performance to field-scale behavior. The second test used RDX seeding to match detonation velocities of small-scale to field-scale tests. The third test, for facilities lacking the instrumentation, was as Go/No-go test, utilizing RDX spiking. In addition, the uniqueness of the ammonium ion among cations as well as the sensitivity of the lower oxides of chlorine (ClO3-) and nitrogen (NO2-) were observed. Although the ammonium salts could be made to detonate more readily than the higher oxides, even without fuel, their sensitivity relative to RDX was not as great as literature might lead one to believe.
Hunter, Justin C., "DEVELOPING A NOVEL SMALL-SCALE TEST TO PREDICT LARGE-SCALE EXPLOSIVITY" (2022). Open Access Master's Theses. Paper 2154.
Available for download on Friday, May 17, 2024