Strain gauge sensitivity improved by using a composite beam

Composite beam connected to strain gauge and mounted on test specimen is capable of amplifying small strains by factor of 10. Tests indicate that resulting output can be 10 times greater than standard method

High-temperature gas/liquid stress relaxometers

Two relaxometers allow testing of elastomers in various fluids. First relaxometer uses fork-like loading spacer interposed between loading lever and support ring, so that sample is stretched predetermined amount. In second relaxometer, degree of initial elongation is set by means of adjustable collar, which, when locked in place on piston rod, enables sample to be stretched predetermined length

Effects of the thermal sterilization procedure on polymeric products

Properties of samples are tested, after thermal exposure, and values are compared with unexposed samples. Thermal stability or compatibility ratings of formulated or compounded organic polymers using trade names are made and degree of change in measured properties is assessed. Products are rated compatible, marginal, or not compatible

Effects of the thermal sterilization procedure on polymeric products

Effects of thermal sterilization on polymeric products used on Ranger and Mariner spacecraf

Heat sterilizable solid-propellant development

The binders tested were polyurethanes made from two hydroxy-terminated polybutadienes, R-45 and Butarez HT, one hydroxy-terminated butadiene-acrylonitrile copolymer, Hycar 1300X 17, and a hydroxy-terminated prepolymer, Esterdiol 560, made from the dimerized fatty acid Empol 1010. The isocyanates used most extensively were isophorone diisocyanate (IPDI) and a polymeric diisocyanate, DDI. Stress relaxation was used to examine the chemical changes that took place in the binder when subjected to the sterilization temperatures. The thermal stability of the oxidizer, ammonium perchlorate (AP), was tested by thermogravimetry in the isothermal and nonisothermal modes. The effect of particle size, recrystallization, moisture content, and doping on the heat stability of AP could be evaluated by this method. The volatile degradation products, obtained when AP samples were aged at 135 C for prolonged periods, were analyzed by mass spectroscopy

Long-term aging of elastomers: Chemical stress relaxation of fluorosilicone rubber and other studies

Aerospace applications of elastomers are considered, including: propellant binders, bladder materials for liquid propellant expulsion systems, and fuel tank sealants for high-speed aircraft. A comprehensive molecular theory for mechanical properties of these materials has been developed but has only been tested experimentally in cases where chemical degradation processes are excluded. Hence, a study is being conducted to ascertain the nature, extent, and rate of chemical changes that take place in some elastomers of interest. Chemical changes that may take place in the fluorosilicone elastomer, LS 420, which is regarded as a fuel and high-temperature-resistant rubber are investigated. The kinetic analysis of the chemical stress relaxation and gel permeation chromatography studies comprise the major portion of the report

Effects of ethylene oxide-Freon 12 decontamination and dry heat sterilization procedures on polymeric products

Effects of ethylene oxide-Freon 12 decontamination and dry heat sterilization procedures on potential spacecraft polymeric material

Compatibility of elastomers in alternate jet fuels

The compatibility of elastomeric compositions of known resistance to aircraft fuels was tested for potential use in Jet A type fuels obtainable from alternate sources, such as coal. Since such fuels were not available at the time, synthetic alternate fuels were prepared by adding tetralin to a petroleum based Jet A type fuel to simulate coal derived fuels which are expected to contain higher amounts of aromatic and hydroaromatic hydrocarbons. The elastomeric compounds tested were based on butadiene-acrylonitrile rubber, a castable Thiokol polysulfide rubber, and a castable fluorosilicone rubber. Batches of various cross-link densities of these rubbers were made and their chemical stress relaxation behavior in fuel, air, and nitrogen, their swelling properties, and response to mechanical testing were determined

Coal desulfurization process

A method for chlorinolysis of coal is an organic solvent at a moderate temperautre and atmospheric pressure has been proven to be effective in removing sulfur, particularly the organic sulfur, from coal. Chlorine gas is bubbled through a slurry of moist coal in chlorinated solvent. The chlorinated coal is separated, hydrolyzed and the dechlorinated. Preliminary results of treating a high sulfutr (4.77%S) bituminous coal show that up to 70% organic sulfur, 90% hyritic sulfur and 76% total sulfur can be removed. The treated coal is dechlorinated by heating at 500 C. The presence of moisture helps to remove organic sulfur

Development and evaluation of elastomeric materials for geothermal applications

A material for a casing packer for service for 24 hours in a geothermal environment was developed by synthesis of new elastomers and formulation of available materials. Formulation included use of commercial elastomer gumstocks and also crosslinking of plastic (high Tg) materials. Fibrous reinforcement of fluorocarbon rubbers was emphasized. Organic fiber reinforcement did not increase hot properties significantly. Glass fiber reinforcement gave significant increase in tensile properties. Elongation was reduced, and the glass-reinforced composition examined so far did not hold up well in the geothermal environment. Colloidal asbestos fibers were also investigated. A few experiments with polyphenyl ether gave material with low tensile and high compression set. Available high styrene SBR compositions were studied. Work to date suggests that new synthetic polymers will be required for service in geothermal environments