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High-resolution synchrotron x-ray radiography with computed tomography is used to observe the evolution of porosity created by thermal exposure in two HMX-based polymer-bonded explosive compositions; LX-04 and BX-63. The measurements were made in situ, over an extended period of time, during which the samples were heated on a slow-rate thermal trajectory. The tests ended with thermal-runaway to ignition after which the samples were consumed by combustion. The primary means of damage appears to be from mechanical debonding of the HMX-binder interface with secondary contribution from chemical decomposition. Confinement and binder properties affect the amount of porosity and permeability that develops. Additionally, observations were made describing the emergence and structure of an internal ignition volume, the formation and transport of a pre-ignition melt layer, and how the early stages of combustion were affected by material morphology, mechanical confinement and melt. The contact angle between molten HMX and the fluoropolymer, Viton A, is also presented. For the first time we have time-resolved x-ray images of ignition in sufficient detail to verify the mechanism of cookoff in polymer-bonded explosive compositions.

The response of Viton B, a fluorinated tripolymer, to one dimensional shock loading has been investigated using manganin stress gauges as the diagnostic. These have been mounted such that they are sensitive to both the longitudinal and lateral components of stress. In the case of the longitudinal gauges, mounting at multiple locations within the target assembly also allows measurement of shock and release velocities as well. Results show that in terms of shock velocity and stress and shear strength, results from Viton B lie a little higher than the corresponding results for polytetrafluoroethylene (PTFE), but more similar to those of polyvinylidene difluoride (PVDF). However, in terms of the release velocity, the behaviour of Viton B is more akin to PTFE. We believe that there are two competing mechanisms at play; an electrostatic repulsion between chains due to the presence of electronegative fluorine atoms that acts against interchain interactions (hence the low shock and high release velocities) and interchain entanglement (tacticity) due to the presence of trifluoromethyl side groups on one of the monomer sub units. This will result in a greater shock velocity and increase in shear strength behind the shock front (when compared to PTFE) as adjacent polymer chains physically interact via entanglement. This should reduce the release velocity for similar reasons; however the release behaviour of Viton B and PTFE is similar. We thus suggest that the electrostatic repulsion between chains may be acting over a longer length scale than interchain entanglement.

Viton O-rings will be used for critical seals of the liquid scintillator veto detector for the sodium iodide with active background rejection dark matter experiment in Australia. In this study, the combined effects of elevated temperature plus exposure to air and linear alkyl benzene (LAB) on the physical and chemical properties of Viton O-rings were investigated over time using compression set measurements and Young’s modulus tests, ATR-FTIR spectroscopy and the analysis of solvent-induced swelling. The measurements show the degradation of physical and mechanical properties of the Viton O-rings was found to be more pronounced under compression set conditions in air for the same temperature compared to LAB at the same temperatures. The ATR-FTIR results show that the effects of LAB on the surface composition of the Viton O-rings were not significant. According to solvent swelling analysis over time, the Viton O-rings are suitable for use with LAB as there were no obvious physical and chemical property degradations at three different ageing temperatures (22, 35 and 55 oC). Furthermore, the overall conclusion is that the O-rings can be expected to function efficiently for much longer than the expected operating life of the SABRE experiment.

Stem sealing plays an important role in valve operation, to avoid leakage from the valve stem area to the environment. Additionally, accuracy and tight sealing of stem seals are vital in fugitive emission applications where hazardous fluids such as gases or vapours may escape if a valve is not sealed properly. Soft thermoplastic and elastomer materials such as Teflon (PTFE), lip seal, V-pack, Viton as well as graphite or graphoil can be used for valve stem sealing. Appropriate stem sealing or packing depends on the process conditions where the valve will be used, including being able to withstand extreme temperatures, being resistant to aggressive fluid such as $${\text{H}}_{2}$$ S containing fluid, displaying a low friction factor to the stem, providing very good sealing capability to prevent leakage from the valve stem area, and being adequately strong and economical. The sealing capability of compression packing is defined as the ability to expand laterally against the stem and stuffing box wall when stressed by tightening the gland. The stem sealing arrangement depends on the type of valves being used and the applications. The sealing capability and performance of a valve can be validated by testing the valve stem sealing through mechanical and temperature cycles based on different American Petroleum Institute standards or by finite element analysis. The torque required to operate a valve depends on parameters such as the packing or stem sealing material, number of stem sealing rings, load of gland flange, stem surface finish, temperature, and cycling. Reducing the number of packing rings can reduce the valve torque and the actuator sizing but removing rings can also increase the risk of leakage from the valve and reduce the effectiveness of the valve seals.

Metal-Fluorocarbon compositions are the pyrotechnic formulations which have been widely used in infrared decoy flares to protect aerial targets from infrared guide missile seekers. In this work, the effect of Mg-Al alloy powder (i.e. the particle size and the content) on the combustion and the infrared emission characteristics (i.e. the infrared emission distribution and the infrared radiance) of the pyrotechnic composition based on Mg-Al alloy, polytetrafluoroethylene (PTFE) and Viton rubber are described. The results show that the high burning rate (with the values of 4.0 mm.s-1 to 10.0 mm.s-1, depend on the compression density) of this composition is achieved with a high content of Mg-Al alloy or when using fine Mg-Al alloy particles as well as coarse PTFE particles. On the other hand, the infrared emission radiance (in the wavelength range of 2.5 μm to 5.0 μm) of Mg-Al/PTFE/Viton composition reaches maximum values (i.e. 17.7 W.cm-2.Sr-1 and 21.0 W.cm-2.Sr-1 with the size of Mg-Al particles are 20 μm and 120 μm, respectively) at 60 wt% Mg-Al alloy. Finally, the Mg-Al/PTFE/Viton composition has a similar combustion and emission characteristics as the Mg/PTFE/Viton composition.

Magnesium/polytetrafluoroethylene/Viton (MTV) fuel-rich pyrolants use the atmospheric oxygen as a complementary oxidizer to sustain and alter the performance of the combustion reaction. The flame d...

Elastic moduli of tissues and synthetic polymeric materials are important design properties needed to develop new implants. In this paper we report the use of vibrational optical coherence tomography (VOCT) to measure the resonant frequency and calculate the modulus of tissues and synthetic polymers non-invasively and non-destructively in vitro and in vivo. Values of tissue and polymer moduli were obtained by applying an audible sinusoidal sound wave to the surface of each specimen. The sound wave travels to the interior of the material and is reflected back to the surface from underlying layers. A spectrum of resonant frequencies and moduli are then obtained. By analyzing the frequencies at which the maximum displacements are observed the resonant frequencies are determined of the material components and the moduli can then be calculated from calibration equations. The characteristic spectrum of resonant frequencies measured is a finger print by which the composition of the underlying tissue components can be determined using VOCT. The resonant frequencies of cells and tissues range from about 40 Hz for fat to about 990 Hz for lamellar bone. The modulus for these tissues ranges from about 1 MPa (cells) to that for extracellular matrix components that range from 2 to 173 MPa (tissue macromolecular components). Measurements reported on synthetic polymers indicate that the resonant frequency ranges from 80 Hz (silicone rubber) to 2800 Hz (acrylonitrile butadiene styrene) and values of the modulus are found to be between 2 MPa and 2120 MPa, respectively. The resonant frequency and modulus are shown to decrease as a result of fatigue in Viton rubber. It is concluded that the width of the resonant frequency peak is related to the molecular weight distribution and that VOCT may serve as method to rapidly determine molecular weight distributions and properties after cyclic loading of uncrosslinked and crosslinked polymers.

Magnesium/Teflon/Viton or MTV based pyrotechnic composition has been the most preferred composition for decoy flares against conventional heat-seeking missiles for more than four decades. MTV flare...

Graphite has attracted scientific interest due to its exceptional physical and chemical properties. On combustion, graphite particles offer high emissivity as a black body; therefore, it can find wide application in advanced decoy flares. Thermite particles (metal oxides/metal) can offer a high reaction temperature that is required to stimulate emitting species. In this study, graphite particles were employed with super-thermite Fe2O3 NPs. Novel Mg–Al bimetal alloy was employed as a reactive metal fuel; Viton A (fluorocarbon polymer) was employed as an energetic binder. Multi-component nanocomposite flares were developed via granulation with subsequent pressing. The thermal signature was measured using the IR spectrometer. Nanocomposite flares based on 6 wt% graphite and 2% Fe2O3 NPs demonstrated superior spectral intensity. This flare formulation offered an increase in average intensity by 248% to reference formulation. It offered the highest relative intensity value θ of 0.54. Graphite, as an allotrope of carbon, acts as an excellent source of carbonaceous materials that can strengthen incandescence emission.

Pentaerythritoltetranitrate (PETN), Cyclotrimethylenetrinitramine (RDX), Cyclotetramethylenetetranitramine (HMX) are important high explosives used in a variety of military and industrial formulations. The present work investigates the interaction Ammonium Perchlorate with RDX, HMX and PETN and the effect of the interaction on the thermal decomposition of Ammonium Perchlorate. The microencapsulation of modified AP crystal was done with Viton. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) were used to investigate the thermal properties and heat of decomposition. Kinetic analysis was done by Flynn Wall Ozawa (FWO) method. Scanning Electron Microscopy (SEM) was used to study the surface morphology of modified AP. The decomposition products were analysed by TG-MS. The presence of RDX/HMX/PETN or its decomposition products appears to catalyse the decomposition of AP.

Infrared (IR) guided missile is known to cause 90% of aircraft damage. Magnesium/Teflon/Viton (MTV) decoy flares are customized materials, which are capable of yielding thermal signature to interfere with IR guided missile seekers. In this study, the IR-signature of an MTV flare is measured in a jet engine nozzle. The jet engine IR-signature is characterized with two characteristic peaks over the α-band (2–3 µm) and β-band (3–5 µm); this is correlated to black body emission at 690° C. The MTV decoy flare with 65% Mg offers an increase in the average intensity of the α- and β-bands by 21 and 4 times, respectively, to that of the jet engine. Quantification of emitting species in the combustion flame is conducted by using the ICT thermodynamic code. The developed MTV formulation offers the relative intensity ratio of the α- and β-bands equal to 0.96, which is comparable to that of an aircraft (0.7).

Thermal batteries are unique direct current (DC) electrical power sources with long shelf live, high reliability and higher power density than classical alkaline batteries. This paper gives a brief overview into the working principle of thermal batteries and reviews the properties of zirconium/barium chromate (Zr/BaCrO4) pyrolant previously used as first fire and iron/potassium perchlorate (Fe/KClO4) pyrolant (Heat), commonly applied as heating pellet in thermal batteries and its hazard properties. The review gives 64 references to the public domain. CAS-Nos. Zr: [7440-67-7], BaCrO4: [10294-40-3], Fe: [7439-89-6], KClO4: [7778-74-7], Viton: [9011-17-0].CAS-Nos. Zr: [7440-67-7], BaCrO4: [10294-40-3], Fe: [7439-89-6], KClO4: [7778-74-7], Viton: [9011-17-0]. Keywords: Barium chromate, Heat-powder, Iron, Lithium, Molten salt, Potassium perchlorate, Pyrotechnics, Thermal battery, Zirconium

Elastomer seals are essential for zonal isolation in vertical and deviated wells. They are often used either as O-rings (static seals) or as energized seals (packers). For elastomers to perform their functions effectively over an extended period, it is essential that the elastomer withstand the deleterious effects of pressure, prolonged loading effects, severe temperature, corrosive fluids, and acidic gases. As such it is imperative to understand the various elastomer degradation mechanisms and develop methods to reduce the degradation. The objectives of this study are: to investigate if elastomers are “fit for service” for well construction applications and to evaluate elastomer performances under downhole corrosive conditions. To achieve this goal, some dynamic wellbore conditions which close-to-real field conditions are were simulated in a controlled laboratory setup. The following properties were investigated: elastomer hardness, elastomer compression, and elastomer volumetric swelling. In the experimental setup, four frequently used elastomers in the oil and gas industry were studied: Nitrile butadiene rubber (NBR), Ethylene propylene diene monomer (EPDM), Fluoroelastomer (FKM) commonly known as Viton, and Polytetrafluoroethylene (PTFE). The results indicate that NBR exhibited the most significant deterioration. Viton showed the least amount of deterioration but has poor decompression resistance. The aging condition that proved to be the most damaging is CO2. Analysis of Variance (ANOVA) was also performed on the data from the samples as a statistical analysis indicator. Some other observations and conclusions are that the degree of chain growth and chain rupture depends on the temperature and the degree of chemical exposure.

We present a miniaturized active multi-way microvalve, with a rotor, measuring only 3.7 mm in diameter and having a footprint of only about 14 mm2, and that is designed for integration into microfluidics chips, allowing for overall size reduction for microfluidics platforms. It has a zero dead volume, and an overall internal volume of only 268 nL. Its operation is based on a rotary mechanism, with compressible rotor and complementary stator seat valve specially designed to have five-degree rotational symmetry, and in which the rotor is made of Viton elastomer to provide a seal and switch between outlets precisely. The microvalve, which can be manually, as well as automatically actuated, is able to withstand pressures up to 370 kPa with no leakage and has a switching torque of under 0.03 Nm. Agency for Science, Technology and Research (A*STAR) National Environmental Agency (NEA) Accepted version This research is supported by the National Environment Agency (NEA) of Singapore (project number ETRP 1302 108) and the Singapore Institute of Manufacturing Technology (SIMTech) under the Agency for Science, Technology and Research (A*STAR).

The aluminum–fluorine reaction is attracting growing interest due to its higher density over aluminum–oxygen. Fluorine rich polymers are particularly interesting for their applications as an energetic binder in advanced additive manufacturing of energetic materials. In this paper, three soluble polymers of PVDF (59 wt% F), Viton (66 wt% F) and THV (73 wt% F) are incorporated with aluminum nanoparticles (Al NPs) and prepared as free-standing films using solvent-based direct writing. The three composite films are compared for their mechanical properties as well as the ignition and combustion performance. Tensile stress was found to order as Al/PVDF > Al/THV > Al/Viton while the elasticity of Al/Viton is much higher than the other two. The burn rate of different composite films increases with Al content, while the flame temperature peaks slightly fuel-rich. The Al/PVDF had the highest burn rate, however, the flame temperature ordered as Al/THV (∼2500 K) > Al/Viton (∼2000 K) > Al/PVDF (∼1500 K), consistent with fluorine content. With higher fluorine and lower hydrogen content, THV releases more CFx gas than HF, which generates higher temperature. However, HF which is predominantly produced from PVDF has the lowest ignition by far and may be responsible for its high flame speed.

The Infrared (IR) guided missiles have posed serious threats to aircrafts flying even at considerably high altitude. An effective counter measure to this imminent threat of the heat seeking missiles is IR decoy flares constituting of Magnesium/Teflon/Viton (MTV) based pyrotechnic composition. The provisioning of MTV flares primarily for defence applications globally is controlled by very few foreign firms who have ensured that the manufacturing techniques and performance parameters are closely guarded owing to economic as well as strategic reasons. Hence, there are limited research papers available which illustrates the mechanical pressing of the MTV composition to form pellets and the performance evaluation of these pellets. The present paper is an attempt to study the density of 50 mm diameter pellets by varying the charge mass of pellets and the applied load to compact the MTV composition. The applied load is varied in steps of 1 ton for a fixed pyrotechnic charge mass mixture of 100 gm for a fixed dwell time of 15 seconds. It is observed that the density of pellets increased with increase in application of load up to an applied load of 8 tons. This phenomenon is owing to reduction in porosity of the mixture as well as brittle fracture of magnesium particles facilitating optimisation of density of pellets. Similar phenomenon was observed by varying the charge mass and the optimum density was obtained for a L/D ratio nearing unity. Thus, the range of process parameters which is found to be of interest for development of pellets of this dimension is 100 gm to 140 gm of charge mass and 6 tons to 8 tons of applied load.

Many subcomponents of nuclear equipment are manufactured using polymers, where it could be highlighted the role of elastomers as sealants. The aim of this work is to analyze several mechanical and thermal properties of BUNA-N, Neoprene and Viton intended to nuclear power applications. Neoprene (polychloroprene) is the better option if the levels of irradiation are the highest postulated and it exhibits the most balanced performance between required properties, showing also the best mechanical behaviour. On the other hand, the analysis of activation energies provided by EPRI 1009748 exhibits that BUNA-N shows the greatest qualified lifetime.

This study examines the influence of various electrical parameters on the volume resistivity of the Viton fluoroelastomer. The transient current, the temperature dependence of volume resistivity, the voltage dependence of resistivity, and the surface morphology of Viton insulators are investigated for new and aged specimens. An accelerated aging process has been employed in order to simulate the natural aging of insulators in service. A detailed comparison between the new and aged samples is presented. The transient effect, which is a challenge to the resistivity measurement of insulators, has been investigated. The first 60 s of the resistivity measurement test showed a significant influence from the transient effect and should be excluded from the data. The volume resistivity of both new and aged samples decreased when the temperature increased. However, the resistivity of the aged sample was lower than the new one at all tested temperatures. When the temperature increased from 35 to 190 °C, resistivity decreased from 4.77 × 1010 to 6.99 × 108 Ω-cm for the new sample and from 2.6 × 1010 to 6.68 × 108 Ω-cm for the aged sample under 500 V. Additionally, the results from this study showed that the volume resistivity is inversely proportional to the applied voltage. Finally, scanning electron microscope (SEM) micrographs/images allowed us to closely examine the surface morphology of new and aged Viton samples. The surface of aged samples has been recognized with higher surface roughness and more significant surface cracks leading to poor performance under high voltage applications.

In this work, FOX-7 (1,1-diamino-2,2-dinitroethylene)-based polymeric microspheres were successfully prepared by the spray-drying method, in which recrystallized FOX-7 grains were integrated with Viton (dipolymers of hexafluoropropylene and vinylidene fluoride). FOX-7/Viton granules were prepared by water slurry method for comparison. FOX-7/Viton microspheres possessed a hollow structure with a typical shell thickness of 870 nm. The particle size of FOX-7/Viton grains on the shell of microspheres was significantly reduced from 33.31 μm (raw FOX-7) to 750 nm. Compared with raw FOX-7 and FOX-7/Viton granules prepared by the water slurry method, FOX-7/Viton hollow microspheres possessed a lower value of apparent activation energy in the thermal decomposition process and a higher characteristic height (H50), which indicates increased thermal decomposition rate and better safety performance. VST test showed that three samples had acceptable thermal stability.

Carbon Capture, Utilisation and Storage is essential to reduce anthropogenic greenhouse gas emissions and limit the average global temperature rise below the 2°C target. In order to promote safe operations throughout the chain, considerations on the performance of transportation and conditioning materials, including propensity for elastomers degradation are some key engineering challenges to be considered for CO2 transportation systems. Therefore, this work presents a characterisation methodology and findings on the performance of several elastomer materials undergoing prolonged (up to 400 h) exposure to supercritical CO2 under pipeline conditions (95 bar and 40oC). The work considered the presence of saturated H2O in the stream as well as the addition of H2S or SO2 as contaminants (500 ppm). Findings show that Neoprene, Ethylene Propylene and Buna N seals have a propensity to lose mass after the exposure, potentially due to degradation of plasticisers contained in their matrix. PTFE-coated samples of such materials moreover exhibited significantly higher mass loss, suggesting degradation of the coating in this environment. Conversely, Viton showed a modest increase of mass after the test, potentially representative of a high-degree of interaction between the material and the fluid. Viton moreover demonstrated to be a potentially unsuitable material choice due to its propensity for rapid gas decompression damage, manifested in extensive presence of cracks on the cross-section surface.

[EN] In this paper, several parts consisting of polymeric materials are studied, in order to determine if they are affected when they are kept in contact with biodiesel at constant temperature and pressure. The samples used are constituted by polymers of silicone (S), acrylonitrile (AN) and propylene hexafluor (Viton-V7). These materials have been selected for investigation because they form part of an industrial process in which they are used, and have been observed early wear characteristics thereof. They consist of seals and cords which are in contact with biodiesel. These materials were kept immersed in biodiesel at atmospheric pressure at a temperature of 40°C for time periods up to 120 days. Virgins tested ones are characterized by various techniques: OM, SEM, XRD, DTA-TGA, among others. Viton sample was the least affected by treatment, while the acrylonitrile sample is the one that has shown the greatest variations., The authors thank Testing Laboratory belonging to the Mechanical Department of the FRSN for roughness measurements, the company AES for materials provided, and the UTN for financial support.

Infra-red decoy flares constituting of Magnesium, Teflon and Viton or MTV, is the most widely acceptable off-board counter measures among majority of the defence forces across the world. These flares are essentially pyrotechnic compositions operating in the range of 3–5µm wavelength owing to the selective emission of the combustion products (MgO, MgF2 and oxides of carbon namely CO and CO2). However, literature on manufacturing techniques and performance characteristics of standard configurations flare pellets developed and supplied by few firms globally is somewhat restricted. Hence, this study is an attempt to evaluate the performance of mechanically pressed 50 mm diameter cylindrical MTV pellets. While varying the process parameters viz. charge mass and applied load for pelleting, the cross-sectional area of the pellets and dwell time of applied load have been maintained constant. With increase in applied load, elastic/brittle fracture of the particles occur which increases surface area of contacts between particles. The optimum density was achieved at 8 tons of load. Similarly, the improvement in density with increase in charge mass was observed till L/D ratio of unity was achieved. SEM images confirmed the increase in contact surfaces and reduction in size of particles owing to elastic/brittle fracture. With increase in applied load, the available surface area decreased and there was a conspicuous increase in burn time. With increase in charge mass, the quantity of pyrotechnic mixture available for burning increased leading to increase in burn time.

We have investigated the shock response of detonation nano-diamonds under dynamic conditions using the Dynamic Compression Sector of the Advance Photon Source for the purposes of understanding the potential fracture mechanism of nano-diamonds and to identify potential avenues for structural energy release. Commercial detonation nano-diamonds exhibit a compressed core, expanded shell that has been proposed to be a potential source for structural bond energy release under a fracture condition. Dynamic diffraction images from two-stage light gas gun experiments to 5.3 km/s were collected on compressed samples of nano-diamonds and Viton fluoropolymer binder mixture in various shock states. Powder diffraction data is refined to extract out core/shell changes with shock loading and show a bimodal response where the shell signal decreases with shock loading while the core signal shows a non-fractured response. These points to a partial fracturing of the nano-diamond particle without accompanying energy release from the core.

During production, storage and manipulation of explosive materials it is important to be able to evaluate potential risks when they come in contact with each other or with other non explosives materials. For this reason various analytical and instrumental methods are being developed and implemented to study the chemical compatibility of explosives with other materials. In this research a possibility has been examined of application of thermal method-Differential Scanning Calorimetry (DSC) and Vacuum Stability Test (VST) as methods to determine the compatibility of often used explosive materials: Octogen (HMX), Pentrite (PETN) and Ammonium Perchlorate (AP) with also often used polymer materials: polyamide 12 (PA 12), Hydroxyl Terminated Polybutadiene (HTPB), fluoroelastomer (Viton A). Standard STANAG4147 was used as criteria to estimate the compatibility between the observed materials.

cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX) is a relatively available bicyclic nitramine in the present. Due to the high energetic content of its molecule (deformation of valence angles) it has heat of formation higher than β−1,3,5,7-tetranitro-1,3,5,7-tetrazocane (β−HMX) by nearly three times. As a result, it has heat of explosion and relative explosive strength exceed that of β−HMX including their corresponding PBXs. However, penetration abilities of PBXs based on HMX are higher than those based on BCHMX. The relatively high initiation reactivity of BCHMX could be modified in a wide range by its incorporation in a suitable polymeric matrices. Regarding to the performance, coating of BCHMX crystals by 5 wt% Viton A produces the maximum performance while the mixture of BCHMX with polydimethylsiloxane (PDMS) seems to be the optimum composition for the development of PBX with low sensitivity. Keywords: BCHMX, Initiation, Sensitivity, Explosive strength, Penetration

To evaluate equipment survivability of the polymer Viton, used in sealing materials, the effects of its thermal degradation were investigated in severe accident (SA) environment in a nuclear power plant. Viton specimens were prepared and thermally degraded at different SA temperature profiles. Changes in mechanical properties at different temperature profiles in different SA states were investigated. The thermal lag analysis was performed at calculated convective heat transfer conditions to predict the exposure temperature of the polymer inside the safety-related equipment. The polymer that was thermally degraded at postaccident states exhibited the highest change in its mechanical properties, such as tensile strength and elongation. Keywords: Equipment Survivability, Severe Accident, Thermal Degradation, Thermal Lag Analysis, Viton

Super-thermites can offer large amount of energy up to 16736 J/g. Flares based on super-thermites can offer superior thermal signature to countermeasure infrared (IR) guided missile seekers. This study reports on the sustainable fabrication of mono-dispersed Fe2O3 nanoparticles of 3 nm average particle size. Colloidal Fe2O3 nanoparticles were harvested from their synthesis medium and re-dispersed in acetone. Fluorocarbon polymers (teflon and viton) as well as aluminum metal fuel were integrated into Fe2O3/acetone colloid. The colloid mixture was granulated and mold pressed to develop the desired grain. The impact of Fe2O3 nanoparticles on thermal signature was assessed using (FT-MIR 1–6 µm) spectrometer. Flame propagation was investigated by video imaging of combustion wave. Combustion zones were quantified using image analysis. Quantification of flame temperature and main IR emitting species was performed using ICT thermodynamic code (virgin 2008). Nanocomposite flare with 12 wt% Fe2O3 offered an increase in the intensity of β band by 230% to that of reference formulation. The primary reaction zone was extended by 164%. Super-thermite particles not only offered superior spectral performance but also altered the combustion mechanism.

This work aims to evaluate degradation of viscoelasticity in terms of creep of four sealing elastomers (flouroelastomer/Viton A®, silicon rubber/vinyl-methyl silicone, chloroprene rubber and ethylene-propylene-diene monomer) upon exposure to engine lubricant and diesel by using digital image correlation technique in a creep experiment for determination of changes in creep behavior of elastomers. Short creep experiments (3 h) were conducted under a tensile load of 1.5N before and after the immersion in the fluids. Also, standard compatibility tests were simultaneously conducted to determine changes in mass, volume, tensile and tearing strengths, and hardness to extend the degradation study. Hence, the creep compliance behavior of the samples was successfully obtained and the creep degradation due to immersion tests was determined. It was found that this alternative method for evaluation of creep degradation of elastomers is very suitable and useful since very low complexity and strain measurement accuracy.

High hardness Flouroelastomers (copolymer of ethylene-tetrafluoroethylene-perfluoro methyl vinyl with Advanced Polymer Architecture) compound was used to make thick and large size O-rings and field tested in pipeline valves containing very sour gas. The sour gas contains 23% H2S, 11% CO2, CH4, low molecular weight hydrocarbons, amine corrosion inhibitors, methanol and water at 32°C and 1200 psi. The results show that after the field test these O-rings were in good conditions and were completely resistance to sour gas and no cracks, bubble, blister, swelling, hardening and softening in the O-rings were observed and they were resistant against the H2S, methanol, amine corrosion inhibitors and steam. High pressure of the system did not produce any defects due to explosive decompression phenomenon or did not cause extrusion in these O-rings. A lower hardness compound also were used to prepare small size and thin O-rings, after O-rings test in very sour gas pipelines valves they were in good conditions. However when thick and large size O-rings were prepared with this compound and tested in the above mentioned field test there were cracks and blisters on the surface of O-rings. Therefore only higher hardness compound can be used to make thick and large size O-rings and its mechanical properties and chemical resistance are proper for this application.

The present study is devoted to comprehensively evaluating the combustion performance of Mg-based (Magnesium/polytetrafluoroethylene/Viton) solid fuels in high-altitude operating environments. A small-scale sealed CO2 laser ignition experiment system is designed to produce different negative pressure environments. A high-speed camera (HSC) and an infrared thermal imager are used to cooperatively capture the burning process. The results obtained demonstrate that the area of the flame core zone and the flame temperature increase significantly as the pressure increases. It is conducive to the heat feedback of the gas phase reaction zone to the solid phase heating zone, resulting in an increase in the burning rate. As the Mg content increases, the flame temperature is decreased and the burning rate is increased. The burning rate for the Mg-based solid fuels is found to increase monotonically with ambient pressure and to follow the Vieille’s law in the pressure range of 0.02–0.1 MPa. Based on the experiment, a three-dimensional combustion-flow coupling solution model is established including the detailed aerobic combustion reaction kinetic model and the eddy dissipation concept (EDC) model. Numerical simulation results reveal that the content of incompletely reacted Mg increases as the pressure decreases. Conversely, the decreasing behavior of oxygen partial pressure at low pressure reduces the probability of reaction of Mg with O2, resulting in a dramatical decrease in the mass fraction of MgO. The scientific findings provide useful insight for the deep understanding of the combustion behavior of Mg-based solid fuels, and support for the increasing demands for both military and civilian applications.

We report our study of stress relaxation of Viton™ A hexafluoropropylene-vinylidene fluoride co-polymer fluoroelastomer compressed 25% and irradiated at room temperature in air to nominal absorbed doses of 10 – 106 Gy with 1.17 and 1.33 MeV gammas from a cobalt-60 source. Our data show that the true stresses at room temperature in ring samples of Viton™ A fluoroelastomer compressed 25% decline slightly from 1014±93 kPa at zero dose to 996±115 kPa at a dose of 103 Gy, decrease to 967±98 kPa at 104 Gy and then drop sharply to 640±116 kPa at 105 Gy and 157±32 kPa at 106 Gy. We briefly discuss the implications of this data for the integrity of seals in high-radiation environments.

A series of detonation performance experiments are described for the plastic-bonded high explosive (HE) PBX 9012, nominally composed of 90% octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX) and 10% polymeric binder vinylidene-hexafluoropropylene copolymer (Viton VTR-5883), by weight. The experiments provide information on the PBX 9012’s detonation propagation properties and metal pushing characteristics. Although this HE formulation has been in use for 50 years as a booster (compositionally similar to LX-07), our new data represent the first full detonation performance characterization for the HE (along with recently reported shock initiation experiments). Here, we compare the new PBX 9012 data with the well-studied PBX 9501 (95% HMX and 5% polymeric binder), establishing how the 5% difference in HMX content between the explosives is manifested in the performance measurements. A scaling argument based on the known energetic material content in a large selection of high HMX content formulations is also given to help explain the observed results. Finally, the accumulated PBX 9012 data is used to generate performance models using both programmed and reactive burn techniques, providing an additional avenue to compare PBX 9012 to the more energetic PBX 9501.

Mass spectrometry has been widely used in lander missions to characterize the volatiles in rocks and soils on planetary surfaces. A good vacuum seal is very important for introducing such solid samples to a vacuum chamber and ejecting them. However, multiple measurements require many metal gaskets, leading to extra weight and complexity for the instruments. In this study, we investigate the capability of three kinds of elastomeric O-rings (Viton, Nexus-SLT, and Nexus-FV) as vacuum seals for mass spectrometric measurements, particularly for in situ K–Ar dating on Mars. First, thermal cycle tests revealed that low-temperature-resistant O-rings can maintain pressure