Daniel N. Preston

Small-scale explosives sensitivity saftey testing: A departure from Bruceton

In order to safely work with explosives, their sensitivity to external stimuli needs to be characterized. The Bruceton method for evaluating explosives sensitivity results has been used effectively for over six decades. This has included the skid test on the large scale, and the friction and drop weight impact tests on the small scale. The result was a 50% probability of reaction, useful for ranking the comparative responses of various explosives in order to make a practical assessment of handling safety. This paper summarizes the limitations of the Bruceton method and introduces the efficacies of the D-optimal test method. A comparison of the two approaches is provided using results for RDX, HMX, and PETN. For this paper, the Los Alamos Type 12 Drop Weight Impact apparatus is used to generate and compare 50% drop heights (H50), or mean probability of reaction, using the Bruceton and D-optimal methods. The results show that the mean obtained by the D-optimal method is not significantly different from the ...

Understanding and manipulating the sensitivity of nitrate ester explosives

Understanding the factors that influence sensitivity is critical for the design and screening of new energetic molecules and materials, but it is often difficult to isolate a single variable to analyze its effect. Pentaerythritol tetranitrate (PETN) is a very common nitrate ester explosive that has been widely studied due to its use in military and commercial explosives. We have developed PETN derivatives with modified sensitivity characteristics by substituting the -CCH2ONO2 moiety with other substituents, including -CH, -CNH2, -CNH3X, -CCH3, or -PO. We relate the handling sensitivity properties of each PETN derivative to its structure, and discuss the potential roles of the central atom, oxygen balance, thermal stability, heat capacity, crystal structure, and inter- and intramolecular hydrogen bonding on impact sensitivity. Reactive molecular dynamics (MD) simulations of the C, H, N, O-based PETN-derivatives have been performed under cook-off conditions that provide insights into how the substituents change the initial chemistry and decomposition paths.Understanding the factors that influence sensitivity is critical for the design and screening of new energetic molecules and materials, but it is often difficult to isolate a single variable to analyze its effect. Pentaerythritol tetranitrate (PETN) is a very common nitrate ester explosive that has been widely studied due to its use in military and commercial explosives. We have developed PETN derivatives with modified sensitivity characteristics by substituting the -CCH2ONO2 moiety with other substituents, including -CH, -CNH2, -CNH3X, -CCH3, or -PO. We relate the handling sensitivity properties of each PETN derivative to its structure, and discuss the potential roles of the central atom, oxygen balance, thermal stability, heat capacity, crystal structure, and inter- and intramolecular hydrogen bonding on impact sensitivity. Reactive molecular dynamics (MD) simulations of the C, H, N, O-based PETN-derivatives have been performed under cook-off conditions that provide insights into how the substituents ch...

Characterization of diacetone diperoxide (DADP)

To date, diacetone diperoxide (DADP) has been significantly less studied than its well-known counterpart, triacetone triperoxide (TATP). Much of this disparity in the literature is due to the harsher conditions/multi-step syntheses required to obtain DADP leading to much lower evidence of frequency of use. Because of this, DADP is often misrepresented as being more dangerous (i.e. more sensitive and less stable) than TATP. This paper discusses the synthesis and characterization (sensitivity, thermal stability, etc.) of DADP with comparisons to other energetic organic peroxides (TATP, HMTD and MEKP) and differences in polymorphism, crystal habit and effects of aging and processing differences are discussed. Additionally, the deflagration-to-detonation transition (DDT) behavior of DADP is discussed with comparison to TATP.To date, diacetone diperoxide (DADP) has been significantly less studied than its well-known counterpart, triacetone triperoxide (TATP). Much of this disparity in the literature is due to the harsher conditions/multi-step syntheses required to obtain DADP leading to much lower evidence of frequency of use. Because of this, DADP is often misrepresented as being more dangerous (i.e. more sensitive and less stable) than TATP. This paper discusses the synthesis and characterization (sensitivity, thermal stability, etc.) of DADP with comparisons to other energetic organic peroxides (TATP, HMTD and MEKP) and differences in polymorphism, crystal habit and effects of aging and processing differences are discussed. Additionally, the deflagration-to-detonation transition (DDT) behavior of DADP is discussed with comparison to TATP.

Tailoring the sensitivity of initiating explosives

Pentaerythritol tetranitrate (PETN) is a very common nitrate ester explosive that has been widely studied due to its use in military and commercial explosives. Recent experimental work and calculations have shown that substituting the central carbon atom of PETN with a silicon atom results in an extremely sensitive contact explosive. We have attempted to develop PETN derivatives which are less sensitive, by attaching hydrogen, amino, and methyl groups to the central carbon atom, and substituting the central carbon atom (and one -CH2ONO2 group) with phosphorous oxide. We relate the handling sensitivity properties of each PETN derivative to its structure, and discuss the role of the central atom, oxygen balance, thermal stability, and inter- and intramolecular hydrogen bonding on impact sensitivity.

Introduction to High Explosives Science

These are a set of slides for educational outreach to children on high explosives science. It gives an introduction to the elements involved in this science: carbon, hydrogen, nitrogen, and oxygen. Combined, these form the molecule HMX. Many pictures are also included to illustrate explosions.

Measurements of near-field blast effects using kinetic plates

Few tests have been designed to measure the near-field blast impulse of ideal and non-ideal explosives, mostly because of the inherent experimental difficulties due to non-transparent fireballs and thermal effects on gauges. In order to measure blast impulse in the near-field, a new test has been developed by firing spherical charges at 152 mm (6 in) from steel plates and probing acceleration using laser velocimetry. Tests measure the velocity imparted to the steel plate in the 50 – 300 μs timeframe, and are compared with free-field overpressure measurements at 1.52 m (5 ft) and ms timescales using piezoelectric pencil gauges. Specifically, tests have been performed with C4 to probe the contributions of ideal explosives and charge size effects. Non-ideal aluminized explosive formulations have been studied to explore the role of aluminum in near-field blast effects and far-field pressure, and are compared with formulations using LiF as an inert surrogate replacement for Al. The results are compared with other near-field blast tests and cylinder tests, and the validity of this test is explored with modeling and basic theory.