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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.

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.

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.

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.

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

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.

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

Red phosphorus (RP) a highly efficient smoke-producing agent. In this study different contents of RP are added into the Magnesium/PTFE/Viton (MTV)-based composition, with the aim of investigating the influence of RP on the burning and radiance properties of MTV-based composition by using a high-temperature differential thermobalance method, a Fourier Transform Infrared (FTIR) remote-sensing spectrometer, a FTIR Spectrometer and a far-infrared thermal imager. The results show that RP improves the initial reaction temperature and reduces the mass burning rate by 0.1–0.17 g·s−1 (34–59%). The addition of RP has no obvious effect on the burning temperature and far-infrared radiation brightness, but the radiating area raises substantially (by 141%), and thus improves the radiation intensity (by 155%).

This paper summarizes the small scale thermal exposure test results of the performance of metallic and polymeric O-ring seals typically used in radioactive material transportation packages. Five different O-ring materials were evaluated: Inconel/silver, ethylene-propylene diene monomer (EPDM), polytetrafluoroethylene (PTFE), silicone, butyl, and Viton. The overall objective of this study is to provide test data and insights to the performance of these O-ring seals when exposed to beyond-design-basis temperature conditions due to a severe fire. Tests were conducted using a small-scale stainless steel pressure vessel pressurized with helium to 2 bar or 5 bar at room temperature. The vessel was then heated in an electric furnace to temperatures up to 900 °C for a pre-determined period (typically 8 h–9 h). The pressure drop technique was used to determine if leakage occurred during thermal exposure. Out of a total of 46 tests performed, leakage (loss of vessel pressure) was detected in 13 tests.

The tensile relaxation modulus of Viton A fluoroelastomers is calculated from the stress-strain response for different strain rates and temperatures using non-equilibrium molecular dynamics simulations. The calculated relaxation modulus is superimposed onto a master curve and compared with the experimentally measured relaxation modulus obtained using dynamical mechanical analysis. Comparison is also made with relaxation modulus calculated from equilibrium molecular dynamics simulation via the Green-Kubo relation and with analytical value of the glassy modulus calculated on the basis of a molecular lattice. Excellent correlation with experimental results is observed at times corresponding to the onset of the glass transition. The simulations capture β-relaxation that is compatible with Arrhenius theory at the onset of the glass transition and at the transition to α-relaxation. The proposed method is time efficient and in most cases more accurately reproduces the experimental behavior compared with the Green-Kubo relation.

We propose a method using a permeable membrane to separate Ne from Ar for Ne isotope analyses in a future planetary exploration, in particular, for the Martian surface. The results of simulation based on permeation data and theoretical formulas show that significant amounts of 20Ne without 40Ar permeate through Viton (fluoropolymer elastomer) and Kapton (polyimide) with appropriate thicknesses. Considering the simulation results, the amounts of 20Ne and 40Ar that permeate through 1 ​mm-thick Viton and 125 ​μm-thick Kapton were determined experimentally. The amounts of permeated 20Ne agree with those of 20Ne obtained by the theoretical calculation within experimental uncertainties. The amounts of permeated 40Ar are as small as those of the background, which is also consistent with the fact that the calculated amounts of 40Ar through those membranes are several orders of magnitude lower than the background 40Ar. In the present experiments, 20Ne/40Ar ratios increased up to 1 for Viton and 200 for Kapton from the terrestrial atmospheric ratio of 1.8 ​× ​10−3 after permeation for 30 and 60 ​min, respectively. A Kapton sheet efficiently enhances the 20Ne/40Ar ratio and enables measurement of the Ne isotope composition without the significant 40Ar++ interference in planetary exploration. Assuming the Martian atmospheric pressure (7 ​hPa) and composition (2.3 ​ppm for 20Ne and 1.9% for 40Ar), the amounts of 20Ne and 40Ar that permeate through Kapton were calculated. The 20Ne/40Ar ratio can be increased up to ca. 1 using 75 ​μm-thick Kapton with a duration time of 30–60 ​min, where the contribution of 40Ar++ is approximately 10% of 20Ne+ and the uncertainty after the 40Ar++ correction is estimated to be a few percent. An effective area of 50 ​cm2 is required if the sensitivity of the QMS used in this study is assumed.

To improve reaction rate of energetic materials, electrospray technology was applied to develop microspheres in which recrystallized cyclotrimethylene trinitramine (RDX) was integrated with nano-Al (nAl) particles and Viton through a two-solvent strategy. Results on morphology properties and chemical heterogeneity demonstrated that the electrosprayed microspheres were hollow spheres containing well-dispersed RDX. It was suggested that RDX nano-crystals adhere tightly on both sides of the nAl@Viton skeletons, thereby increasing the contact area among components. The thermal analysis of the microspheres indicated that nAl particles accelerated the energy release by decreasing the apparent activation energy for microsphere decomposition. Experimental results showed that electrosprayed nAl@RDX@Viton had shorter laser ignition delay and more vigorous combustion flame than the physical mixture, which benefitted from the characteristic structure and synergistic effects of the components.

The surface of magnesium particles was modified by coating with Viton as an energetic polymer using solvent/non-solvent technique. Taguchi robust method was utilized as a statistical experiment design to evaluate the role of coating process parameters. The coated magnesium particles were characterized by various techniques, i.e., Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and thermogravimetry (TG), and differential scanning calorimetry (DSC). The results showed that the coating of magnesium powder with the Viton leads to a higher resistance of metal against oxidation in the presence of air atmosphere. Meanwhile, tuning of the coating process parameters (i.e., percent of Viton, flow rate of non-solvent addition, and type of solvent) influences on the resistance of the metal particles against thermal oxidation. Coating of magnesium particles yields Viton coated particles with higher thermal stability (632 °C); in comparison with the pure magnesium powder, which commences oxidation in the presence of air atmosphere at a lower temperature of 260 °C.

A new approach for depositing thin energetic films is introduced using doctor blade casting. Magnesium (Mg) and manganese dioxide (MnO 2 ) is mixed with a solvent that includes a binder and is blade cast onto a foil substrate. This study investigated the effect of binder chemistry and concentration on combustion behavior. The Mg–MnO 2 system was studied in the following binder–solvent systems: Polyvinylidene Fluoride (PVDF) – Methyl Pyrrolidone (NMP); Viton® fluoroelastomer (Viton A) – acetone; and, paraffin–xylene. Films were cast onto substrates to approximately 100 μm thickness. Calorific output and flame velocity were measured for varying binder concentration. Calorific output increased with increasing binder concentration, to a maximum of 4.0 kJ/g, suggesting participation of the binder in the exothermic reaction. Flame velocity decreased with increasing binder concentration, with a maximum of 0.14 m/s. Binders are less conductive than metals and metal oxides thereby hindering the energy propagation with increasing binder content. Confined flame propagation tests were also conducted for the NMP/Mg–MnO 2 –PVDF system, with a maximum recorded flame velocity of 3.5 m/s. High velocity imaging shows considerable differences in flame front, which may suggest a transition in propagation mechanism accounting for the observed increase in flame velocity.

In this paper, the decomposition reaction models and thermal hazard properties of 1,3,5-trinitro-1,3,5-triazinane (RDX) and its PBXs bonded by Formex P1, Semtex 1A, C4, Viton A and Fluorel polymer matrices have been investigated based on isoconversional and combined kinetic analysis methods. The established kinetic triplets are used to predict the constant decomposition rate temperature profiles, the critical radius for thermal explosion and isothermal behavior at a temperature of 82. °C. It has been found that the effect of the polymer matrices on the decomposition mechanism of RDX is significant resulting in very different reaction models. The Formex P1, Semtex and C4 could make decomposition process of RDX follow a phase boundary controlled reaction mechanism, whereas the Viton A and Fluorel make its reaction model shifts to a two dimensional Avrami-Erofeev nucleation and growth model. According to isothermal simulations, the threshold cook-off time until loss of functionality at 82. °C for RDX-C4 and RDX-FM is less than 500 days, while it is more than 700 days for the others. Unlike simulated isothermal curves, when considering the charge properties and heat of decomposition, RDX-FM and RDX-C4 are better than RDX-SE in storage safety at arbitrary surrounding temperature. © 2014 Elsevier B.V.

This work describes thermal decomposition behaviour of plastic bonded explosives (PBXs) based on mixture of l,3,5,7-tetranitro- 1,3,5,7-tetrazocane (HMX) and 2,4,6- triamino-1,3,5-trinitrobenzene (TATB) with Viton A as polymer binder. Thermal decomposition of PBXs was undertaken by applying simultaneous thermal analysis (STA) and differential scanning calorimetry (DSC) to investigate influence of the HMX amount on thermal behavior and its kinetics. Thermogravimetric analysis (TGA) indicated that the thermal decomposition of PBXs based on mixture of HMX and TATB was occurred in a three-steps. The first step was mainly due to decomposition of HMX. The second step was ascribed due to decomposition of TATB, while the third step was occurred due to decomposition of the polymer matrices. The thermal decomposition % was increased with increasing HMX amount. The kinetics related to thermal decomposition were investigated under non-isothermal for a single heating rate measurement. The variation in the activation energy of PBXs based on mixture of HMX and TATB was observed with varying the HMX amount. The kinetics from the results of TGA data at various heating rates under non-isothermal conditions were also calculated by Flynn–Wall–Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. The activation energies calculated by employing FWO method were very close to those obtained by KAS method. The mean activation energy calculated by FWO and KAS methods was also a good agreement with the activation energy obtained from single heating rate measurement in the first step decomposition.

The thermal behavior and decomposition kinetics of Fluorel-bonded PBXs based on some attractive cyclic nitramines were explored by means of non-isothermal TG and DSC techniques. The exothermic onset temperatures on DSC curves of RDX-FL, BCHMX-FL, HMX-FL and CL-20-FL were noticed at 208.7, 235.6, 277.2 and 239.2 °C with the peak maximum of 233.8, 237.4, 278.8 and 239.5 °C, respectively. The corresponding heat releases are 1758, 1393, 1546 and 1893 J g−1, which are much lower than that of the pure cyclic nitramines. According to DSC peak shift, similar to Viton A, Fluorel polymer is probably not chemically compatible with BCHMX resulting in much lower thermal stability and heat of decomposition compared with pure BCHMX. It is also proved that Both Fluorel and Viton A could decrease or inhibit the autocatalytic effect occurring during liquid-state decomposition of RDX. However, opposite to Viton A, the Fluorel polymer could enhance the autocatalytic effect of BCHMX due to bad chemical compatibility. The activation energies for thermolysis of RDX-FL and CL-20-FL are found almost independent on the conversion rate (0.3 < α < 0.7) with the mean values of 170 ± 3, and 206 ± 3 kJ mol−1, while those of BCHMX-FL and HMX-FL are largely dependent on the conversion rate with average values of 189 ± 4 and 117 ± 5 kJ mol−1.

The thermal behavior and decomposition kinetics of Viton A bonded PBXs containing some attractive cyclic nitramines were investigated by means of nonisothermal TG and DSC techniques. It has been shown that only a single decomposition process has been observed for RDX-VA, CL-20-VA and HMX-VA while an obvious two-step process for BCHMX-VA under 1.0 °C min −1 . The exothermic onset temperatures of RDX-VA, BCHMX-VA, HMX-VA and CL-20-VA were found as 212.6, 241.3, 277.6 and 237.8 °C with the peak maximum of 234.1, 242.6, 278.7 and 238.6 °C, respectively. Their corresponding heat releases were determined as 1552, 1263, 1302 and 1597 J g −1 , which are much lower than that of the pure cyclic nitramines. It has been proved that Formex polymer is not good binder for BCHMX, while Viton A is better than C4 and Formex as the binder of cyclic nitramines for the sake of greater thermal stability. Viton A has a significant effect on the activation energy distribution of cyclic nitramines, and the initial autocatalysis effect for RDX and BCHMX was weakened or inhibited. The activation energies for thermolysis of RDX-VA, BCHMX-VA, HMX-VA and CL-20-VA were found almost independent on the extent of conversion at interval of 0.3–0.7 with the mean values of 174.4 ± 3.1, 183.3 ± 1.3, 285.8 ± 11.7 and 184.0 ± 4.3 kJ mol −1 , respectively.

Stress-elongation behavior of a Viton A-401C based compound established for backup seals of 500 MW(e), Prototype Fast Breeder Reactor is depicted. Stress-softening effects are negligible during room temperature (RT) or 110 °C measurements on unaged samples at strain rates of 50 mm/min and 500 mm/min because of low filler content. Relaxation is observed during RT property determination at lower strain rate. Stiffening of behavior at 50 mm/min and 110 °C is attributed to Joule-Gough effect and absence of relaxation because of increased molecular chain mobility. The two zone stress-elongation behavior (determined by chemical cross-links up to ∼85% strain and by ionic interactions beyond) propounded in the article by combining air-aged specimen data (32 weeks at 140/170/200 °C) provides a behavior map of bisphenol cured, low filler, fluoroelastomers made of vinylidene fluoride and hexafluoropropylene. This could be extended to peroxide cured fluorocarbon rubbers for verifications and providing qualified compounds of better grades for critical nuclear elastomeric sealing applications.

Identification of a set of governing physico-mechanical properties for inflatable seals of Prototype Fast Breeder Reactor (PFBR) and specification of their limits is described based on operating requirements, design practices and results from seal development. The limits of tensile strength, elongation at break, hardness, tear strength, fluid compatibility, compression set and specific gravity defined for the Viton GBL 200S/600S based inflatable seal formulation provide a standardized framework for regular production of reactor seals and a streamlined approach for compounding, design, manufacture and quality control. This assures significant reduction of efforts during the envisaged unification of Fast Breeder Reactor sealing based on four variations of inflatable seal compound which could result in a universal design code apart from significant gains in safety, reliability and life. The property set has potential use in Pressurized Heavy Water Reactor and Advanced Heavy Water Reactor. Inclusion of factors such as batch-to-batch variations of compound properties and their reproducibility during laboratory measurements, hot tensile behavior of fluoroelastomer, long term ageing effects and the margin of safety at the end of seal design life ensures the utility of property set in attaining its intended objective.

Against problems in terms of stability, airtightness and so on of current fast sealing airbag, stability and airtightness of fast sealing airbag in simulating tunnel was studied through combining theoretical analysis and experiment. The ideal viton material is finally found after comparing and analyzing heat resistance, flame resistance, wear resistance, hardness and air permeability of different kinds of rubber. Sealing and wind blocking effects of airbags made from selected material are tested in simulating tunnel. Rate of air leakage and changing rate of wind pressure of each kind of rubber are also determined and further verified, with result that both indexes of viton material are the least, respectively only 4.25% and 4.66%.

The development of a fluorohydrocarbon rubber compound for static backup seals of 500 MWe, Prototype Fast Breeder Reactor (PFBR) is depicted. Variations of a previously developed Viton A-401C based formulation were subjected to processability tests, accelerated heat ageing in air, mechanical characterization and production trials. Finite element analysis and literature data extrapolation were combined with long term ageing to ascertain the life (minimum 10 years) of chosen formulation in reactor under synergistic influences of 110 °C, 23 mGy/h (γ dose rate) and air considering postulated accidental conditions. Validation of test seals and quality assessment indicate that composition and properties of the validated laboratory compound has been translated effectively to the reactor seals, installed recently in PFBR. The tensile and hardness specimens indicated negligible degradation and exceptional thermo-oxidative stability of the seal compound during ageing (32 weeks at 140/170/200 °C) even though interesting manifestations of cross-link exchange and ionic interactions were observed. Compression set results, showing definite trends of change under ageing and stain, were used in Arrhenius and Williams Landel Ferry equations for realistic life prediction. The development provides a foundation to simplify and standardize the design, development and operation of major elastomeric sealing applications of Indian nuclear reactors based on a few qualified compounds.

The feasibility of producing thin-walled fluoroelastomer profiles under continuous, atmospheric-pressure vulcanization conditions in air has been demonstrated by successful manufacture of ∼2 m diameter test inflatable seals for the 500 MWe, Prototype Fast Breeder Reactor (PFBR) using a 50/50 blend formulation of Viton ® GBL-200S/600S based on advanced polymer architecture (APA). A commercial cold feed screw extruder with 90 mm diameter screw was used along with continuous cure by microwave (2.45 GHz) and hot air heating (190 °C) at a line speed of 1 m/min to produce the seals. The blend formulation promises significant improvement in the performance and safety of the seals. This article depicts the relevant characteristics of the original inflatable seal compound that was used as reference to achieve the objectives through synchronized optimization of material and production technologies. The production trials are outlined and the blend formulation used with minor factory modifications to produce the test seals is reported. Progressive refinements of the original, Viton ® A-401C based compound to the blend formulation is presented along with an assessment of potential performance gains. Possible uses of the reported formulation and production technique for other large diameter, high temperature seals of PFBR are indicated along with the envisaged activities en-route the production of perfected reactor inflatable seals.

The deteriorations of polymeric materials for a SPE-type high-level tritiated water electrolyzer composed of the Water Detritiation System (WDS) against sulfonic acid environment and radiation environment were discussed. A long-term durability of VITON, AFLAS, denaturated polyphenylene ether, and Kapton polyimide immersed in a sulfonic acid was demonstrated. Negligible degradation in percent elongation at break of these polymeric materials was observed up to the immersing period of 2 years. The detectable radiation deterioration in ionic conductivity of Nafion® N117CS ion exchange membrane irradiated with electron beams up to the integrated dose of 1500 kGy was measured. The ionic conductivity of Nafion® N117CS ion exchange membrane irradiated at more than 1000 kGy was slightly deteriorated. As for the elastomers for its use as a seal, the radiation degradation in hardness of VITON, AFLAS was investigated. Considerable degradation in softness of these rubbers for its use as a seal was not observed up to the integrated dose of 1500 kGy. The water uptake of rubbers was generally increased as the integrated dose was increased. However, irradiated VITON rubbers had constant water uptake up to the integrated dose of 1500 kGy.

A diffusion-bonding procedure at a low temperature, i.e. 500 °C, based on the high mobility of silver atoms was developed with a newly designed plate-and-frame type hydrogen purification membrane module consisting of a unit cell and a housing. Two membranes made of palladium and copper sputtered on polished porous nickel supports (PNS) followed by Cu-reflow at 750 °C, respectively, were assembled in a unit cell to verify that the low temperature diffusion-bonding method could be applied to gas-tight membranes. Ring-shaped silver foils with a thickness of 50 μm were placed between the membranes and the unit cell body made of nickel plate. A pair of membranes, a pair of silver foils and the unit cell body were compressed with a pair of covers and eight screws by a 17 cm long torque wrench at 12 N m. The diffusion-bonded unit cell was welded in a module housing comprised of a feed port and a retentate port by a laser-operated welder. After the module was constructed, gas-tightness tests were carried out using helium and the measured helium leakage was 8 × 10−5 mol m−2 s−1 at 0.7 MPa, which is the same as the value detected before diffusion bonding with a Viton O-ring. The hydrogen permeation test and durability test consisting of three cycles of alternately changing the temperature and transmembrane pressure difference were carried out using a single gas, hydrogen, and it was found that the hydrogen permeation flux remained constant during the durability test and that the helium leakage did not increase after the durability test.

The radiation durability of the polymers in the solid-polymer-electrolyte (SPE) water electrolyzer of the water detritiation system (WDS) was investigated. A series of γ-ray and electron beam irradiation tests on the Nafion® N117 ion exchange membrane (a key polymer in the SPE electrolyzer, beyond the ITER-WDS requirement (530 kGy)) indicated that the Nafion® N117 membrane had sufficient radiation durability (up to 1600 kGy) with regard to the mechanical strength and the ion exchange capacity. To maintain the electrolysis function of the SPE cell up to 530 kGy, we suggest replacing the Teflon® insulator with a polyimide insulator. Any serious damage in the tensile strength of the Kapton® polyimide (up to 1500 kGy) was not observed during the γ-ray irradiation tests. Regarding the rubber material selection for the O-ring seal, we observed that the VITON rubber swelling in the water kept the tensile strength value constant (up to 1500 kGy). Moreover organic elution was not observed in the water after irradiation. With regard to its stable tensile strength and negligible organic elution, VITON rubber is a suitable material for the O-ring seal.

Headspace SPME GC/MS was used to monitor the volatile degradation products generated by syntactic polysulfide alone and in the presence of Viton A at elevated temperature. This approach allowed the identification of products from two distinct degradation mechanisms. In one degradation mechanism, which is associated with lead oxide-cured polysulfide, a single cyclic disulfide compound dominated the outgassing signature. The second mechanism was evident only when the polysulfide was in the presence of Viton A at 70 °C. In as little as 24 h, the Viton-exposed polysulfide generated multiple outgassing species indicative of an acid-catalyzed degradation process. Within one week of exposure to Viton A, the syntactic polysulfide softened significantly and lost over 6% of its initial mass, and after four weeks, the polysulfide was no longer a solid material.

Telone is a potent fumigant that is based on the chlorinated unsaturated hydrocarbon, 1,3-dichloropropene (1,3-DCP). It is often applied without dilution and so poses severe inhalation and air pollution threats. Urinary metabolites of 1,3-DCP have been detected after Telone skin exposure, so that preventing dermal exposure is also important. The objective of the study was to assess if nitrile and multi-layer (“laminated”) gloves provide adequate protection against Telone EC™ formulation. To accomplish this, disposable (Safeskin™) and chemically resistant (Sol-Vex™) nitrile and laminated (Barrier™ and Silver Shield™) glove materials were challenged by Telone EC™ with hexane liquid collection in an ASTM-type I-PTC-600 permeation cell. Analyses of cis- and trans-1,3-DCP in the collection fluid at specified times were performed on a moderately polar capillary column by gas chromatography-electron capture detection. Telone EC™ caused microholes in both nitrile materials, though the chemically protective material was degraded slower than the disposable nitrile. The laminated gloves offered limited protection. Silver Shield™ protected best because 1.5–2.3 mg 1,3-DCP permeated by 8 h relative to 2.5–7.6 mg for Barrier™, implying about 2.5 times more protection for 8 h. Even for Silver Shield™, the extent of protection was inadequate as illustrated by a risk assessment of the skin exposure situation. The normalized breakthrough times for both types of laminated gloves varied between 27 and 60 min. It is recommended that Viton gloves still be worn for protection.

Thermolysis of keto-RDX (K-6) and its plastic bonded explosives (PBXs) containing Kel F and Viton A was studied using various thermo-analytical techniques. The PBXs decompose at slightly lower temperatures than K-6 with higher heat release. Kinetic analysis of isothermal TG data was done by using both model fitting methods and a model free isoconversional method. Model fitting methods gave nearly same values of activation energy for all the samples. But the model free isoconversional method showed that the activation energy is dependant on extent of conversion and different values were obtained for thermolysis of K-6 and PBXs. The value of activation energy converged to a limit above α ≈ 0.75. This limiting value was close to the activation energy obtained by model fitting methods. Rapid thermolysis of the samples was studied using ignition delay measurements and deriving kinetic parameters out of the data. Activation energy for thermal ignition was nearly the same for all the samples.

A water reclamation plant (WRP) uses a fine bubble-diffuser system to treat biological sewage waste. The process involves pumping air through slits in rubber membranes to feed bacteria in the waste stream. This case study deals with problems encountered with shrinking and hardening of the EPDM rubber membranes. Several factors affecting the performance of the rubber were investigated, including “leaching” of plasticizers, accelerated cross-linking due to the effects of temperature, and vulcanization effects on rubber flexibility. Different rubber materials were evaluated (i.e. silicone, Hypalon, Viton, neoprene, and a different formulation of the EPDM rubber). The investigation found that EPDM compound 7195 provided superior performance and met the required parameters for the wastewater treatment application. Additional investigations revolved around improving pumping losses in membrane through optimized perforation sizes and the inclusion of a cooling system (water misting or heat-exchanger) to cool the air before it reaches the membrane.

The effect of a rubber mould on densification and deformation of aluminum alloy powder was investigated during warm isostatic pressing. The hyperelastic constitutive equations based on various strain energy potentials were employed to analyze deformation of a rubber mould. The parameters in the strain energy potentials were obtained from experimental data for uniaxial and volumetric responses of Viton rubber at elevated temperatures. The yield function of Shima and Oyane was implemented into a finite element program (ABAQUS) to predict compaction responses of metal powder during warm isostatic pressing. Finite element results were compared with experimental data for densification and deformation of aluminum alloy powder during warm die pressing and warm isostatic pressing.

The gas system for the Outer Tracker of the HERA-B experiment at DESY produces the desired counting gas mixture Ar/CF4/CO2 65:30:5 and circulates it through the detector at a flow rate of 20 m 3 / h , i.e. ∼1 vol / h . It controls flows and regulates pressures in all 26 OTR half-superlayers, purifies the gas upon return from the detector, and automatically performs a quantitative analysis of main and trace (O2, N2, H2O) gas components for the common input and the outputs of all half-superlayers. The first running experience and the strategies employed during system construction to avoid any detector aging possibly induced by the gas system are discussed. The large system with major gas purification stations was constructed using only non-outgassing, “clean” materials and devices, such as stainless steel, PEEK, baked Viton, and metal bellows pumps. An epoxy glue was used extensively as a non-outgassing sealing material in applications with up to 100 bar pressure.

Extreme value statistics have been applied to the crevice corrosion front that advances under elastomeric seals to aluminum surfaces. The exponential cumulative extreme value distribution provided an accurate description of the distribution of corrosion fronts quantified by tracing. Extreme value analysis can be applied to seals of small test samples to estimate the most probable maximum corroded depths of larger structures and, thereby, required seal widths. Variations in the calculated most probable maximum corroded depths introduced by subjectivity in tracing are considered. Crevice corrosion kinetics were determined using sets of fixtures salt spray tested for 2–60 days. These fixtures were assembled with 2024-T3 or 380 cast aluminum and silicone adhesive, ethylene–propylene–diene monomer, or Viton rubber elastomeric sealants. An empirical power law function was used to model the most probable maximum corroded depth under the seals versus test time. For tight seals to smooth surfaces, the dependence on time varied as t p with p =0.35–0.40, which is similar to the time dependence obtained in pitting corrosion studies.

Zirconium powder is a powerful reducing agent that reacts with oxidizer at elevated temperature, releasing enough heat to ignite pyrotechnic mixtures. In this work, the thermal properties of Zr/KClO4/Viton A priming compositions made by different preparation methods were first investigated using thermal analysis techniques. Then these priming compositions were pressed into the charge holders of pressure cartridges. The firing characteristics of the pressure cartridge were evaluated by using the Bruceton method. The data indicate that the thermal behavior and firing characteristic of Zr/KClO4/Viton A priming compositions were changed because of the different methods of preparation.

An impact study of cryogenic deuterium pellets on flat metal target plates with and without a Viton rubber covering has been carried out to simulate the pellet transportation in a pellet funnel covered inside with a Viton rubber. The funnel is used to decrease horizontal angular scatter of the pellets to the acceptable degree so that the pellets can pass a Teflon guiding tube with less damage. Results indicate that in both cases, the pellets after impact are of similar performance and nearly ideal damping, and that many pellets with velocity less than 800 m/s can pass through the present pellet funnel. Performance of the pellet injector and the impact study under different pellet incident angles and pellet velocities are described in detail.

The effects of age and repeated cleaning-in-place (CIP) cycles on the hygienic properties of gasket materials used in the food industry were studied. The materials included in the study were EPDM (ethylene propylene diene monomer rubber), NBR (nitrile butyl rubber, also known as Buna-N), PTFE (polytetrafluoroethylene) and Viton (fluoroelastomer). The materials were exposed to prolonged alkali-acid treatments simulating repeated CIP cycles. In addition, materials aged in industrial dairy or brewing processes were examined. Mixed cultures of Bacillus thuringiensis and Pseudomonas fragi or Pantoea agglomerans and Pediococcus inopinatus were used as test organisms and the CIP was performed in an experimental test rig. The susceptibility to biofilm formation and the cleanability in CIP were assessed by the plate count method, epifluorescence microscopy, impedimetry and ATP bioluminescence measurements. Physical deterioration was observed both on experimentally aged materials and on materials aged in industrial processes, causing reduced cleanability. PTFE was most resistant to alkali-acid treatments and repeated CIP cycles. The hygienic properties of EPDM, NBR and Viton degenerated in repeated CIP cycles. The methods used for assessing cleanability are discussed.

Carbon dioxide was used as the solvent in two innovative polymer processes, the preparation of energetic polymers and a Viton based pyrotechnic. The energetic polymer prepared was poly-3-nitratomethyl-3-methyl oxetane and the pyrotechnic was a magnesium, Teflon and Viton (MTV) crumb. Liquid carbon dioxide (LCO 2 ) at 140 atm and 0°C replaces methylene chloride as the solvent in the two step energetic polymers preparation. The monomer, 3,3-(methanol) methyl oxetane, was nitrated with nitrogen pentoxide (N 2 O 5 ) and subsequently polymerized using gaseous boron trifluoride (BF 3 ). Polymerizations in LCO 2 simplifies solvent removal and purification. The LCO 2 solvent evaporates on release of the pressure. Supercritical carbon dioxide (SCCO 2 ) was used for oligomer extraction and fractionation of the polymers. To our knowledge, this was the first time carbon dioxide was used as the processing fluid for N 2 O 5 nitration and for polymerization using gaseous BF 3 . Various batches of MTV up to 200 grams were prepared using a new method designated the Super-Shock Process. The MTV prepared by this new process meets the requirements of a class 1.3 explosive. In this process the Viton was precipitated from an acetone/magnesium/Teflon/Viton paste with carbon dioxide, thus coating the magnesium and Teflon with Viton. Virtually no hazardous waste was generated in this process. The processing fluids, acetone and carbon dioxide were recovered and recycled. Since the starting materials were not chemically or physically altered during processing, any off specification MTV was mixed with acetone and the proper amounts of starting materials and added to the next batch. In the old process over 10 pounds of hazardous waste are produced per pound of MTV.

This article studied the effect of temperature on the radiation induced degradation of fluorine containing elastomers, i.e. AFLAS type (Asahi glass Co. Ltd) and VITON type (Du pont). The temperature range is from 90 to 200°C. The irradiation was performed by 60 Co γ-ray in air oven. Dose rate was 2.5 kGy/h. The weight loss by irradiation increases with increasing temperatures. Ultimate elongation decreases with increasing dose but temperature dependence is small. It was found out that AFLAS type have better radiation resistant properties than VITON type from the experiments.

The molecular migration of nine industrial organic liquids into Du Pont's VITON fluoropolymers has been studied over the temperature interval 25–60°C. Migration has been studied in terms of sorption and diffusion of liquids into the membrane materials. A gravimetric method is used to measure the solvent uptake. From the sorption results, diffusion coefficients have been calculated using Fick's equation. A numerical method has been employed to calculate the liquid concentration profiles in the polymers. The kinetic rate constants have also been calculated from the sorption results. Activation parameters for sorption, diffusion, and permeation have been estimated by a least-squares method using the Arrhenius equation.

Poly(vinylidene fluoride) (PVDF) and the poly(hexafluoropropylene-vinylidene fluoride) (Viton) films are modified in order to produce heparin-like materials. This transformation is carried out on three steps: swift heavy ion irradiation (performed at the GANIL, Caen, France) of the polymer substrates, polystyrene (PS) grafting, functionalization of the PS. X-ray photoelectron spectroscopy is used to analyze the modification of the surface chemical composition at the several steps.

Standard-molded, one piece O-ring food processing plant gaskets (1.5 in or 36.1 mm diameter) made of seven different substances (Buna N, white Buna N, EPDM (ethylene propylene diene monomer), polyethylene, silicone rubber, PTFE (polytetrafluoroethylene or Teflon) and steam-resistant Viton) were treated with chlorine sanitizer or ozonated water. After treatment, only very slight differences were noted visually between control and treated gaskets. Measurements indicated that ozone treatment affected the tensile strength of EPDM and Viton, but not significantly more than chlorine treatment. The tensile strengths of other gasket materials were not significantly affected by ozone treatment. The elasticity of ozone-treated PTFE gaskets was significantly different from chlorine-treated PTFE gaskets. Other gasket materials were not significantly affected by ozone treatment.

A new apparatus for the measurement of excess enthalpies of liquid mixtures based on a Calvet microcalorimeter (C-80 Setaram) is described. Vaporization effects in the calorimetric cells are avoided by means of Viton balloons pressurized with nitrogen. Mixing is performed by precision-injection metering pumps connected to the cells by a piping system. The apparatus permits measurements in the range 25–130°C and up to 2.5 MPa for low boiling and highly viscous components. Results are presented for the water-glycerol system at 50° and 80°C.