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Several shock studies have been made on polyurethane materials, both fully dense and distended in the form of foams. However, there is a lack of shock data between the densities of 0.321 and 1.264 g/cm³ (fully dense).We present here data obtained from two different types of shock experiments at densities of 0.35, 0.5, 0.68, 0.78, and 0.9g/cm³ in order to fill in the density deficiencies and make it easier to develop an unreacted equation of state (EOS) for polyurethane as a function of density. A thermodynamically consistent EOS was developed, based on the Helmholtz free energy, and was used to predict the shock properties of polyurethane materials at densities from 1.264 to 0.348 g/cm³ . These estimates are compared to the available data. The data match quite close to the predictions and provide a basis for calculating polyurethane foam shock processes. Chemical reaction has been observed at relatively high pressure (21.7GPa) in fully dense polyurethane in an earlier study, and the equation of state presented here is representative of the unreacted polyurethane foam. Lowering the density is expected to drop the shock pressure for chemical reaction, yet there is not enough data to address the low density shock reaction thresholds in this study. [ABSTRACT FROM AUTHOR]

One of the more common ammonium nitrate(AN)-based explosives is ANFO, which is a mixture of AN prills and diesel fuel oil (FO) in a 94:6 ratio by weight. Since there are no available shock data on FO, a series of shock compression experiments have been completed using a two-stage light gas gun with a sealed liquid target cell. The FO studied was diesel #2 which has been used in a number of ANFO explosive shots. Density and sound speed data were measured and used to predict and compare the data to a universal liquid Hugoniot (ULH). In-situ magnetic gauges in the target cell were used to measure the particle velocity, shock velocity, and shock wave profiles. Projectile impact velocities ranged from 1.5 to 3.2 km/s, generating input pressures to the FO between 3 and 17 GPa (depending on the impactor material being used). No shock-induced reaction was observed in the FO in any of the experiments. Since the ULH was found to slightly under predict the FO Hugoniot states, a linear Hugoniot was fit to the data - Us = 1.775 + 1.725 up - in mm/μs. A Helmholtz EOS based on the Murnaghan isotherm was developed so the temperature on the Hugoniot could be estimated. At 12 GPa the shock temperature is expected to be 1500K. [ABSTRACT FROM AUTHOR]

Fluoropolymers are widely used in a variety of applications due to their favorable properties that include chemical inertness, low coefficient of friction, and ability to withstand high-temperature operating conditions. Additionally, their high densities also make them desirable materials for use as high explosive binders in plastic bonded explosives. Here, we present the first investigation of the dynamic (shock) and static compression behavior of the fluorinated binder poly(chlorotrifluoroethylene-co-vinylidene fluoride) (Kel-F 800). Kel-F 800 samples prepared by both compression molding and melt-processing methods were studied. We observed little difference in the dynamic behavior of the two materials, despite a difference in crystallinity of 10–15%. A linear Rankine-Hugoniot fit to the Hugoniot loci in the Us-up plane gives Us = 1.838 + 1.824 up. Langrangian sound velocities at pressure were also measured at 3.0 (cL = 4.7 mm/μs) and 4.9 (cL = 5.8 mm/μs) GPa. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A temperature controller system capable of heating and cooling gas gun targets over the range -75°C to +120°C was designed and tested. The system uses cold nitrogen gas from a liquid nitrogen Dewar for cooling and compressed air for heating. Two gas flow heaters control the gas temperature for both heating and cooling. One heater controls the temperature of the target mounting plate and the other the temperature of a copper tubing coil surrounding the target. Each heater is separately adjustable, so the target material will achieve a uniform temperature throughout its volume. A magnetic gauge membrane with integrated thermocouples was developed to measure the internal temperature of the target. Using this system, multiple magnetic gauge shock experiments, including equation-of-state measurements and shock initiation of high explosives, can be performed over a range of initial temperatures. Successful heating and cooling tests were completed on Teflon samples. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Shock-induced chemical reactions remain an area in shock physics that needs further investigation, particularly for determining the influence of pressure, temperature, and chemical structure on reactivity. Several studies have been done in the past that indicate dimerization, polymerization, and decomposition take place in different shock-produced pressure and temperature regimes depending on chemical functionality. We present results obtained from single-shock experiments in which liquids were studied using embedded multiple magnetic gauges to make in-situ measurements of the particle velocity profiles at up to ten Lagrangian positions in the liquid. One of the liquids was organic (tert-butylacetylene) and the other was a closely related silicon-based material (ethynyltrimethylsilane). Multiple wave structures were measured in each liquid when the input pressure was above a certain threshold. Here, the reactivity of these materials are compared. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report here on a collection of shock compression experiments on a silicon polymer foam with varying degrees of distension from low (∼0.4 g/cm3) to the near fully dense material (∼ 1 g/cm3). These experiments are being carried out on a two-stage gas-gun (50 mm bore) with a Kel-F 81 impactor at velocities between 1.5 and 3.1 km/s. Particle and shock velocity measurements are made with magnetic gauges by inserting the gauge package (0.001 inches thick) between layers of 2.3 mm thick foam. Special attention is required for assembly of these targets due to the foam’s low strength. To minimize compression and gaps at interfaces, the foams are positioned between support rings, which are machined to match the foam’s thickness. The Hugoniot data from these experiments is compared to unpublished data obtained with explosively driven flyers at Los Alamos National Laboratory in the early 1980’s. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

A series of shock compression experiments have been undertaken on Teflon using single- and two-stage gas-guns. Peak pressures in these experiments range from a few kbars to over 10 kbars, as well as one shot completed at 117 kbar. Multiple particle velocity wave profiles, at a number of Langrangian positions, are obtained for each experiment using in-situ magnetic gauges. Shock velocity is calculated from arrival times at both the particle velocity gauges and at embedded shock trackers. These direct measurements of particle and shock velocity are compared to previous shock compression results on Teflon. Particular attention is focused in the region below 10 kbar where evidence of a shock induced phase transition has been reported, based upon a cusp in the Hugoniot. The volume change for this transition is only ∼ 2.2 % making its observation difficult. A two-wave structure on the shock front would be strong evidence of the shock-induced transition, but has not been observed in these initial low-pressure experiments. However, the Hugoniot data does show a subtle cusp between two of these shots at pressures of 6.4 and 7.9 kbar. The presence of the cusp is consistent with existing data, but appears at slightly higher pressure. Additionally, the in-situ particle velocity gauges show an evolving wave front, which is likely associated with Teflon’s visco-elastic properties. The wave front is initially steep, but rounds significantly after the wave has propagated several millimeters into the target. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Single-stage and two-stage gas gun experiments have been completed to measure the unreacted Hugoniot of PBX9501 high explosive (HE). Two types of experiments were done: 1) PBX9501 was impacted with a higher impedance projectile and the interface particle velocity history was measured using a magnetic gauge glued to the HE front; 2) a PBX9501 disc was mounted in the front of a projectile that impacted a LiF window and velocity interferometers (VISAR) were used to measure the impact interface particle velocity history. Inputs to the PBX9501 ranged from 3 to 15 GPa in these experiments. Particle velocity waveforms show an induction time followed by a particle velocity change (the nature of the change depends on the type of experiment) corresponding to shock-induced reaction in the PBX9501. The induction part of the waveform provided unreacted Hugoniot information so several new high-pressure Hugoniot points were generated. These data do not indicate a softening in the unreacted Hugoniot at high pressures; more experiments will be necessary to determine this. By using an estimate for the reaction product EOS, it was possible to estimate the average PBX9501 initial reaction rate for each experiment. The induction time decreases with pressure and the reaction rate increases with pressure. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

A line optically-recording velocity interferometer system (ORVIS) was used to measure laser-driven flyer plates impacting windows of various materials. Since the particle velocity can be measured along a line, half the line measured the acceleration of the flyer plate as well as the effect of the impact on the window. The other half of the line measured the jump in particle velocity upon impact with the window because the window was mirrored on that half. This provided information about the flyer velocity and two independent measurements of the interface particle velocity resulting from the flyer impact. Hugoniot data for copper flyers were obtained. In addition, the flatness of the flyer plate during its acceleration and the effect of this flatness on the Hugoniot data obtained are discussed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]