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TATB PBX growth was reduced significantly by using binders other than the Kel-F 800. Kraton G-6500 (a co-polymer of styrene and ethylenebutylene) and three polyester resins exhibited less growth than formulations containing Estane, Vistanex, and Viton A binders.

Viton rubber O rings to be used in the plasma-containment vessel of the ZT-40 torus were molded and tested for their sealing ability. To meet the stringent requirements for these parts, the mold design and mold surface preparation should adhere strictly to the Viton manufacturer's recommendations. In addition, the molding stock must be worked either by injection molding or by a preprocess such as extrusion.

Twenty candidate sealants representing ten different polymer types were evaluated as potential solar collector sealants. Polymer types tested included epichlorohydrin rubber, EPDM rubber, silicone, polysulfide, acrylate rubber, and a fluoroelastomer. Initial screening of sealants consisted of measuring high temperature stability and adhesion retention. Several sealant compositions exhibited satisfactory performance in these tests and were selected for further evaluation. These materials were based on an EPDM rubber, a Viton fluoroelastomer, and silicone polymers. Further testing of these candidate materials included determination of adhesion retention under uv/water/heat conditions, fogging temperature, low temperature flexibility, and physical properties. Four silicone-based materials appeared to be suitable candidates for sealing solar collectors. These include Dow Corning 90-006-02 and 3120, General Electric 1200, and PR-1939 from Products Research and Chemical Corporation.

Sixteen automotive elastomers were investigated in the methanol/gasoline systems. The results show that although few elastomers are affected drastically by pure gasoline (e. g., natural rubber) and few by the pure methanol (e. g., Viton), most of the elastomers are severely affected by mixtures of the gasoline and methanol rather than the pure components. Results on the ethanol/gasoline system are similar to those of methanol except that the ethanol mixtures have slightly less severe effects. Only in the case of Viton a greatly reduced effect in the ethanol system was observed.

Introduction P compositions based on magnesiumTeflon (MT) formulations are characterized by many advantageous properties as rocket motor igniter materials": high-energy content, low hygroscopicity, high degree of safety in preparation, low temperature and pressure dependence of the burning rate, ease of igniter pellet or grain fabrication, favorable aging characteristics, stable burning at low pressures, and low production costs. Viton A copolymer is frequently added to the binary MT mix to increase homogeneity and facilitate product fabrication (by consolidation, extrusion, or injection molding), without a substantial effect on combustion thermochemistry. In addition to excellent resistance to environmental deterioration, magnesium-TeflonViton (MTV) compositions have been noted for good ignition source characteristics. The existence of very hot solid and liquid particles and condensible and reactive species in MTV combustion products enables fast heat transfer to a solid fuel/propellant surface or to combustible gas mixtures by almost all possible modes: conduction from impinging solid particles, forced convection from gaseous species, high thermal radiation, exothermic condensation and solidification, etc. "Soft" ignition of solidpropellant motors (defined by low motor pressurization rate and absence of an ignition peak), which is very desirable in certain propellant grain configurations, is readily obtainable with MT or MTV pellets or granules. For given specific motors and igniter mass flow rates, pyrogen igniters with MTV charges achieved shorter ignition delay times than propellant charges for similar flame temperatures.

A series of boron-filled vinyl copolymer elastomer (VCE) and Viton A fluoroelastomer formulations was prepared and the physical characteristics of the cured formulations determined. Their weight loss on heating to 300/sup 0/C, as determined by two different analytical methods, did not agree. The presence of up to 0.23 percent boric acid in the boron powders used to fill a standard boron-filled VCE elastomer did not appear to affect the physical characteristics of the cured formulation. 7 tables. (auth)

The ASTM cell was utilized to study permeation of chloro-, o-dichloro-, and m-dichloro-benzenes and o- and p-chlorotoluenes through Viton (unsupported) and nitrile (supported and unsupported) glove materials using isopropanol as collecting solvent, and FID/gas chromatography for quantitation. Adequate mixing in the collection chamber was accomplished by externally agitating the ASTM cell at the required speed in a moving-tray water bath at 25 degrees C. The Viton glove did not show permeation even after 4 hours. The nitrile gloves showed breakthrough times of less than 1 hour. The steady state molar flux rates for unsupported or supported nitrile gloves, or for the different challenge solvents were not statistically different. Thus, breakthrough times were better indicators of permeation than steady state molar flux rates. A "mixed" permeation mechanism was proposed, depending on swelling of the glove material.

This final technical report describes the investigation and evaluation of experimental integral fuel tank sealants under laboratory conditions simulating aircraft integral fuel tanks. Materials investigated were Dow Corning 77-028, 77-085, 3M Polyester, TRW Polyimide, Polysulfide and AFML Viton. These materials were evaluated dynamically in a fillet sealed configuration. This report also describes in detail the functions, operations and problems encountered with the dynamic test apparatus that has been designed and fabricated for the purpose of evaluating experimental aircraft integral fuel tank sealants. A portion of the effort was required to diagnose deficiencies and mechanical failures of the testing equipment which resulted in the lack of conclusive data in the report.

The halogenated ethanes 1,2-dichloroethane; 1,1,1-trichlorethane; and 1,1,2-trichlorethane are used as chemical intermediates and in metal working operations, and polychlorinated biphenyls (PCBs) have in the past been used by the tens of millions of pounds in various roles in American industry. Because of the widespread use and hazardous or potentially carcinogenic nature of these compounds, a study was performed to determine the degree of protection which was afforded against these compounds by certain protective garment materials. The materials evaluated in these studies have included: butyl rubber, milled nitrile rubber, neoprene rubber latex, nitrile rubber latex, polyethylene, poly(vinyl alcohol), surgical rubber latex, Teflon, and Viton as well as the following composite or multilayered materials: butyl-coated nylon, polyethylene-coated Tyvek, polyurethane-coated nylon, and poly(vinyl chloride)-coated nylon. The breakthrough time at which each liquid phase compound permeated these materials was studied by the time lag method. For the noncomposite materials, the results of these breakthrough studies were correlated with their equilibrium weight changes following immersion in the test liquids. Results of these studies have shown that most materials currently used in the construction of protective garment material in the United States are of a generally unsatisfactory nature with respect to protecting the worker against themore » halogenated ethanes and the PCB used in this study.« less

Equilibrium water vapor pressure and total moisture content were measured for samples of TATB-10 percent Kel-F, TATB-6 percent Estane, and TATB-9 percent Viton in a temperature range from 296 to 365/sup 0/K. Heats of vaporization were obtained for temperatures from 296 to 333/sup 0/K. Below 333/sup 0/K the water in the samples behaved as dissolved water and the Clausius-Clapeyron equation was applicable, while above 333/sup 0/K the water dissolved in the samples became very mobile and for practical purposes it was considered to be available in its entirety in the gas phase. The total moisture content of the samples was found to be

The development and testing of seals and lubricants for journal-type roller-cone rock bits for drilling into geothermal reservoirs at temperatures over 260/sup 0/C (500/sup 0/F) are described. The conditions experienced by seals and lubricants subjected to geothermal drilling are reviewed along with the basic design requirements for roller-cone bit seals and journal bearing lubricants. Two unique test facilities are described: a seal test machine which simulates pressures, temperatures, and mechanical eccentricities, and a lubricant tester capable of evaluating load-bearing ability at temperature and pressure. Three candidate elastomeric compounds demonstrated 288/sup 0/C (550/sup 0/F) capability and several others demonstrated 260/sup 0/C (500/sup 0/F) or greater capability. Successful elastomeric seal candidates were proprietary compounds based on EPDM, Kalrez, and/or Viton polymers. Three mechanical seals for reservoir temperatures over 288/sup 0/C (550/sup 0/F) are presented. Lubricant screening tests on more than 50 products are summarized, and several newly developed lubricants which meet both the compatibility and lubrication requirements are described. Several seal/lubricant systems are recommended for laboratory or field geothermal drilling tests in roller-cone drill bits. The future availability of drill bits for geothermal use is discussed, as well as the potential spinoffs of the program findings for nongeothermal roller-cone bits.

Stress relaxation measurements were made as a function of temperature and hydrostatic pressure on two lightly filled elastomers (Hypalon 40 and Viton B), one highly filled elastomer (Neoprene WB), and on an EPDM rubber. The latter was not piezorheologioally simple. The lightly filled elastomers showed piezorheologically simple behavior, i.e. their response curves under different hydrostatic pressures could be superposed empirically by a simple horizontal shift along the logarithmic axis. The filled elastomer was piezorheologically simple only in the rubbery region and in the beginning of the transition region. The dependence of the empirical shift distances, log a_p , on P could not be described by either the Ferry-Stratton or the Bueche-O'Reilly equation. By considering the bulk modulus to be linearly related to pressure, a new equation has been developed for log a_(T,P) which describes the pressure dependence well and contains the WLF equation as a limiting case. Published data on the response of poly(vinyl chloride) under superposed hydrostatic pressure are shown to obey the new equation also. The theoretical importance of the new equation lies in the fact that combination of the usual isobaric measurements at atmospheric pressure as function of temperature with isothermal measurements as function of pressure allows, in principle, all the molecular parameters required by the free volume theory to be determined unambiguously.

High temperature seals (elastomeric and mechanical) and lubricants were developed specifically for journal-type rock bits to be used in geothermal well drilling. Results at simulated downhole conditions indicate that five selected elastomeric seals (L'Garde No. 267, Utex Nos. 227, 231 and HTCR, and Sandia Glow Discharge Coated Viton) are capable of 288/sup 0/C (500/sup 0/F) service. Two prototype mechanical seals did not achieve the life determined for the elastomeric seals. Six lubricants (Pacer PLX-024 oil, PLX-043 oil, PLX-045 oil, Geobond Oil, and Geobond Grease) demonstrated 316/sup 0/C (600/sup 0/F) capability. Recommendation is made for full-scale simulated geothermal drilling tests utilizing the improved elastomeric seals and lubricants.

During the first two years of PETRA operation, the vacuum system performance has been analysed to obtain data for the design of future storage rings. According to this analysis, the vacuum requirements on electron storage rings can be more easily attained than commonly expected in the past. PETRA is successfully operating without an in situ bake out or glow discharge cleaning. Further it is shown that low cost Viton sealed gate valves can be unreservedly used and some complicated components, such as electrostatic separators etc., can be built without cooling, since the beam induced mode losses are not locally absorbed. Radiation damage due to Compton-scattered synchrotron light is seen to be a significant problem for high energy storage rings. This calls for a strongly coupled design of vacuum system, magnets and shielding for future electron storage rings.

Samples of Kel-F 800, Viton A and Estane 5702-F1 were annealed at 323/sup 0/K and their crystallinity was tested by x-ray diffraction, thermal mechanical analysis, and differential scanning calorimetry. After annealing for three months, all three samples exhibited some crystalline properties.

Four batches of experimental PETN have been made for incorporation into LX-13 (Extex). A control batch was reprecipitated in the conventional manner (shock reprecipitation from acetone into violently agitated water) while three batches were made in the Micronizer: Two of these were treated with MRL 22A.with one of the treated batches being heat stabilized for 8 hours at 116 C. Two 500-pound batches of RX-04-EC (4% Viton A) were made to supply material for the special studies of the effects of deviations in the composition of LX-10 type explosive. An attempt was made to mold a skid test part from ECX. Inadequate curing of the binder made mold stripping difficult.

State of art review during 1958 showed that rubber-like, room temperature curing, fillet forming tank sealants were limited to use in the 275 to 300 degrees F temperature range. Development progress with sealants based on DuPont Viton A synthesis elastomer were reported during the year, but the development of this material, which is useful to 450 degrees F, was not complete at the year's end.

This report is the second compilation of methods for analyzing explosives. All the methods were developed for routine performance by techniques, and an attempt has therefore been made to keep them as simple as possible. Methods are presented for analyzing plastic-bonded explosives based on sym-cyclomethylenetetra-nitramine (HMX), based on viton in addition to HMX, and based on pentraerythritol tetranitrate (PETN).

Data from sieve analyses of HMX and HMX recovered from LX-04-1 has been compiled for correlation to quality parameters. Particle size distributions on HMX received from LRL have been completed along with other HMX lots specified by them. Sieve analysis of recrystallized PETN was obtained using the now normal procedure for HMX. A statistical investigation of production LX-04-1 examined the dependence of density, elongation, and ultimate tensile strength on particle size distributions ({Pi}) and Viton content. The {Pi} was found to correlate well with density, increases in fines decreasing density. An experimental to determine the effect of binder solvent on HMX {Pi} during removal of Viton from pressed LX-04-1 was performed. This study has indicated no drastic effect on the distribution by the length of time the binder solvent is on the material. HMX and recrystallized PETN surface area measurements obtained form the Perkin-Elmer sorptometer are tabulated in this report. Recrystallized PETN has been examined under the microscope and counts made on the number of crystals with given shape. A frequency distribution was calculated for each group present in a 1 mm{sup 2} area. Experiments to determine the extent of grinding or reduction of particle size of HMX agitated in an ultrasonic vibrator for increasing times have been done. The data have indicated a time of three--five minutes is adequate to disperse agglomerates without undue breaking or grinding of solid crystals. It is possible to do some grinding under severe conditions in the ultrasonic bath.

The ability of Viton B O-ring of 90 Shore A hardness to seal 12,500 psig air pressure was evaluated under dynamic and static simulated-service conditions using solid Teflon back-up rings. Both dynamic and static seals showed small volume leakage after total elapsed times under pressure ranging from 35 to 58 hours. The O-rings showed no defects or evidence of extrusion after test. Leakage may have been due to slow recovery of the O-rings from compression, microscopic defects in the metal and/or rubber surfaces, or to the presence of small particles of compressed Molykote powder, the lubricant used on the O-rings. The rate of leakage was much less than previously reported for similar tests using spiral Teflon back up rings. The swelling of the O-rings caused by sudden release of pressure was low, for example: 1.2% after 1,000 psig pressure and 3.6% after 12,500 psig pressure. The measurements were made one hour after pressure release. The physical properties of Viton B Orings were not greatly affected by six months exposure to oxygen at 60 F and 1,750 pressure.

A dynamic test apparatus has been designed and fabricated for purpose of testing experimental aircraft integral fuel tank sealants. The apparatus is capable of closely simulating the conditions encountered by a sealant during a typical aircraft flight. In addition, the apparatus has the flexibility of simulating a virtually unlimited number of stress, temperature, fuel, and pressure conditions, and will automatically repeat the desired test cycle until sealant failure, occurs. A fillet sealed test joint has been used in the testing to date and with proper joint designs the apparatus will accommodate other types of seals found in aircraft fuel tank construction. Dynamic testing to date has been performed on Dow Corning 77-028, 77-085, 95-526, 77-108, 3M Polyester, a fiber reinforced polyester, and a Viton sealant formulated by the Air Force Materials Laboratory. These materials were all tested in a fillet seal configuration. High temperature aging in JP-7 fuel vapor was performed on the above materials, and physical properties were determined on the aged specimens both at room temperature and selected high temperatures representative of possible aircraft conditions.

This project was initiated to study the manufacture of new explosive formulations. Production and quality parameters are determined; among these are viscosity, composition, particle size distribution, processing variables and raw materials, and their effect on operation, safety characteristics, producibility, and physical and explosive properties. Pastes, extrudables, and PBX`s are among the formulations. One 20-pound batch of XTX-8003 was made to complete a milling study and two 28-pound batches were made to fill an LRL order. No problems were encountered during the manufacturing operation, and test fire results were satisfactory. The effort to resolve some of the problems with LX-04 included evaluating reprocessing techniques and testing various binders. Outstanding elongation results were obtained with Fluorel 1700 binder. Also, a reasonably good elongation was obtained with Lot 16 Viton when the slurry coating was performed in the 100-gallon kettle. The washing and reworking, with extra solvent, of production Lot 27B improved elongation somewhat, but not enough for production acceptance.

Publisher Summary This chapter describes a study to examine heat resisting rubber connectors. Four elastomers were potential candidates for the job: Viton, silicone rubber, hypalon, and polyacrylic rubber. Silicone rubber is intermediate in price but this elastomer has the additional disadvantage of relatively poor physical properties. All samples were placed in an air oven at 130°C, and some were removed for physical testing at intervals of seven days over the period of a month. More significant still for a duty where flexibility is essential is the effect of exposure to heat on the elongation. In the case of butyl, the ultimate effect of heat degradation is to increase the elongation and although this is associated also with its becoming plastic rather than elastic, it is evident that in applications where flexing occurs this is to be preferred to a decrease in elongation and embrittlement.

The purpose of this project is to determine the thermal properties of explosives, and to continue the development and evaluation of thermal tests. Two preliminary experiments were conducted to determine (1) how the time-to-explosion (TE) using Lee Plugs (short stainless steel and aluminum) would compare with the TE obtained using the lead plugs; and (2) how the Lee Plugs would perform with du Pont`s EL-511 and Tacot at 314{degrees}C and 362{degrees}C., respectively. The Pantex-built chromatograph is operating as a two-column instrument, and the findings of an extensive check out of the instrument are reported. The chemical reactivity test sample holders were shown to evolve approximately 30{mu}l of N{sub 2} + O{sub 2} and 3 {mu}l of CO{sub 2} when heated for 22 hours. A number of thermal tests were made on two lots of LX-04-1 (39A and 38B) to determine if any differences could be detected that would explain why Lot 38B tensile strength is much better than 39A when both were made from the same lot of Viton A. Some differences were detected, but they have not been related to the tensile strength of the material. The time-to-explosion for various Adiprenes with HMX are reported, and they indicate that there could be some reactivity between the Adiprene and HMX. Pantex and LASL DTA thermograms and pyrolograms for PETN and Extex are reported for comparison to determine how the sensitivity of Pantex instruments compare with LASL, and if these instruments could be used to qualify PETN and Extex in accordance with LASL Specification 13Y-104481.

Bicyclo-HMX (cis-1, 3, 4, 6-tetranitro- octahydroimidazo-[4, 5-d] imidazole or BCHMX) was studied as a plastic explosive bonded with the C4 matrix and with Viton A. Also a series of nitramines namely RDX (1, 3, 5-trinitro- 1, 3, 5-triazinane), HMX (1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocane) and HNIW (ε-2, 4, 6, 8, 10, 12-hexanitro-2, 4, 6, 8, 10, 12-hexaazaisowurtzitane, ε-CL-20) were studied for comparison with the same types of binders. The detonation velocity, D, of all prepared mixtures was measured. Their thermal stability was determined using non-isothermal differential thermal analysis (DTA). While the C4 matrix lowers the thermal stability of the resulting explosives, Viton A enhances this stability. Approximate relationships between the peaks of exothermic decomposition and the D values were found. The detonation parameters were also calculated by means of Kamlet & Jacobs method, CHEETAH and improved EXPLO5 code for all the mixtures. From the measured D values and the calculated detonation parameters, it is obvious that the detonation parameters of BCHMX-mixtures are very close to HMX-explosives and better than those of RDX- mixtures. It was found that the C4 matrix reduces the difference between the values of energy of detonation in the studied C4 mixtures. As expected, the pressed HNIW-Viton A mixture has the highest detonation parameters of all of the prepared mixtures.

The Dependex sealing concept is a reliable O-ring vacuum seal using Viton or, in special applications, soft metal seals of indium. Dependex fittings are used extensively on accelerator beam lines where high vacuum is acceptable and high-temperature bakeouts are not routine. A method of adapting stainless-steel Dependex fittings for use with OFHC copper gaskets, a seal traditionally employed in all-metal ultrahigh-vacuum systems is described.

Clean Viton and Viton coated with Apiezon-L vacuum grease were tested for their noncontaminating compatibility with channel electron multipliers (CEMs). The test setup and procedure were the same as those used previously in conjunction with CEM compatibility tests of certain epoxies, solder, and fluorocarbon polymer materials useful for construction of spaceflight sensors. While some CEM gain degradation was noted during exposure to Viton and Apiezon-L, the present tests indicate that, at least over instrument lifetimes of about 2 x 10 to the 12th counts, these materials should be suitable for (1) preflight space sensor testing systems, (2) hermetic seals for CEM-based space sensors, and (3) terrestrial CEM-based instrumentation.

Elastomeric materials are natural or synthetic rubber products that are used in a variety of equipment related applications such as seals (O-rings and gaskets), hoses, diaphragms, belts and valve seats. When these materials are placed in storage, they are generally assigned a shelf life. The shelf life defines the time period an item can be stored and maintain physical properties which are considered acceptable for its intended application. Shelf life limitations are usually obtained from the supplier of the elastomer or component or established by the User. Shelf life is typically based on military specification MIL-STD-1 523A or MIL-HDBK-695C. These specifications address most of the commonly used elastomers and provide conservative shelf life restrictions. It is not unusual for utilities and equipment manufacturers to add further conservatism when establishing their shelf life limits. This results in inconsistent shelf life limits that are typically very conservative. In 1956, the Rubber Manufacturer's Association (RMA) sponsored an elastomer natural aging study which lasted ten years. The program concluded that while the physical properties of the elastomers did change, the O-rings were still acceptable. The RMA discontinued the study at this point. Recent test data has been obtained which when combined with the original RMA study results provides information on how physical properties of various elastomers changed due to natural aging over a 31 year period. The elastomers tested included neoprene, viton, nitrile, SBR, ethylene propylene, urethane, butyl, and acrylate. A review of the material property changes resulted in the following conclusions: 1.

Based on our experience with the quadrupole mass spectrometer, an instrument of reduced size, complexity, and with high economy was developed as a gauge for simple residual gas analysis in the high vacuum and down to the ultrahigh vacuum range (limit of detection: 5×10−11 for N2 with unit resolution up to mass 100). The small system can be mounted almost completely as a nude system. No secondary electron multiplier is used. The high vacuum version is bakeable up to temperatures tolerated by Viton gaskets. It is compatible with most of the existing flanges as well as with future types (smallest diameter of the port: 32-mm i.d.). The uhv version (bakeable to 400 °C) is normally mounted on a 2.75-in. (7-cm) o.d. Conflat flange. The importance of the various parameters influencing the operation conditions is discussed in detail considering the restricted range of application.