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Patterson, W. J.

Publications and source records attributed to Patterson, W. J..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Materials and processes laboratory composite materials characterization task, part 1. Damage tolerance

A test run was performed on IM6/3501-6 carbon-epoxy in which the material was processed, machined into specimens, and tested for damage tolerance capabilities. Nondestructive test data played a major role in this element of composite characterization. A time chart was produced showing the time the composite material spent within each Branch or Division in order to identify those areas which produce a long turnaround time. Instrumented drop weight testing was performed on the specimens with nondestructive evaluation being performed before and after the impacts. Destructive testing in the form of cross-sectional photomicrography and compression-after-impact testing were used. Results show that the processing and machining steps needed to be performed more rapidly if data on composite material is to be collected within a reasonable timeframe. The results of the damage tolerance testing showed that IM6/3501-6 is a brittle material that is very susceptible to impact damage.

Nettles, A. T.↗
NASA NTRS1989

Ultra-High-Molecular-Weight Silphenylene/Siloxane Elastomers

Elastomers enhance thermal and mechancial properties. Capable of performing in extreme thermal/oxidative environments and having molecular weights above 10 to the sixth power prepared and analyzed in laboratory experiments. Made of methylvinylsilphenylene-siloxane terpolymers, new materials amenable to conventional silicone-processing technology. Similarly formulated commercial methyl-vinyl silicones, vulcanized elastomers exhibit enhance thermal/oxidative stability and equivalent or superior mechanical properties.

Hundley, N. H.↗
NASA NTRS1986

Ultra-High-Molecular-Weight Silphenylene/Siloxane Polymers

Elastomers having molecular weights above 1 million made by twostage polymerization. Two-stage process proves far more successful than synthesis from reactive monomers. Process involves synthesis of silanolterminated prepolymer and subsequent extension of prepolymer chain with additional aminosilane monomer. Multistage method allows chain-extending monomer added in precise amounts between stages.

Patterson, W. J.↗
NASA NTRS1985

Formulation/cure technology for ultrahigh molecular weight silphenylene-siloxane polymers

Molecular weights above one million were achieved for methylvinylsilphenylene-siloxane terpolymers using a two-stage polymerization technique which was successfully scaled up to 200 grams. The resulting polymer was vulcanized by two different formulations and compared to an identically formulated commercial methylvinyl silicone on the basis of ultimate strength, Young's modulus, percent elongation at failure, and tear strength. Relative thermal/oxidative stabilities of the elastomers were assessed by gradient and isothermal thermogravimetric analyses performed in both air and nitrogen. The experimental elastomer exhibited enhanced thermal/oxidative stability and possed equivalent or superior mechanical properties. The effect of variations in prepolymer molecular weight on mechanical properties was also investigated.

Hundley, N. H.↗
NASA NTRS1985

Thermal design of the space shuttle solid rocket booster

The thermal protection systems (TPS) to meet the quick turnaround and low cost required for reuse of the solid rocket booster (SRB) hardware. The TPS development considered the ease of application, changing ascent/reentry environments, and the problem of cleaning the residual insulation upon recovery. A sprayable ablator TPS material was developed. The challenges involved in design and development of this thermal system are discussed.

Fisher, R. R.↗
NASA NTRS1984

Ultra-high molecular weight silphenylene-siloxane polymers

Silphenylene-siloxane copolymers with molecular weights above one million were prepared using a two stage polymerization technique. The technique was successfully scaled up to produce 50 grams of this high polymer in a single run. The reactive monomer approach was also investigated using the following aminosilanes: bis(dimethylamino)dimethylsilane, N,N-bis(pyrrolidinyl)dimethylsilane and N,N-bis(gamma-butyrolactam)dimethylsilane). Thermal analyses were performed in both air and nitrogen. The experimental polymers decomposed at 540 to 562 C, as opposed to 408 to 426 C for commercial silicones. Differential scanning calorimetry showed a glass transition (Tg) at -50 to -55 C for the silphenylene-siloxane copolymer while the commercial silicones had Tg's at -96 to -112 C.

Patterson, W. J.↗
NASA NTRS1983

Development of Silane Hydrolysate Binder for Thermal-Control Coatings

Technical report describes theoretical and experimental development of methyltriethoxysilane (MTES) hydrolysate binder for white, titanium dioxidepigmented thermal-control coatings often needed on satellites. New coating is tougher and more abrasion-resistant than conventional coating, S-13G, which comprises zinc oxide in hydroxyl-therminated dimethylsiloxane binder.

Patterson, W. J.↗
NASA NTRS1982

Binders for Thermal-Control Coatings

Methyl trialkoxysilane hydrolysates have been found to be superior binders for radiative thermal-control coatings. Using sprayed test panels, candidate coating formulations were optimized with respect to binder/ pigment radio, ethanol content, pigment particle size, coating thickness, and curing conditions. Binders are made from monomers of trialkoxy-silanes or chain-extended alkoxysilanes. Monomers are believed to polymerize to ladder-type structures like methyl silicone.

Patterson, W. J.↗
NASA NTRS1981

Development of silane-hydrolysate binder for UV-resistant thermal control coatings

Detailed characterizaton and formulation studies were performed on a methyltriakoxysilane hydrolysate as a binder for thermal control coatings. The binder was optimized by varying hydrolysis temperature, time, catalyst type, and water concentration. The candidate coating formulations, based on this binder with TiO2 pigment, were optimized via a detailed series of sprayed test panels that included the parameters of binder/pigment ratio, ethanol content, pigment particle size, coating thickness and cure conditions. A typical optimized coating was prepared by acetic acid catalyzed hydrolysis of methyltriethoxysilane with 3.25 mol-equivalents of water over a 24 hour period at room temperature. The resulting hydrolysate was directly mixed with pre-milled TiO2 (12 grams pigment/26 grams binder) to yield a sprayable consistency. Panels were sprayed to result in a nominal cure coating thickness of 2 mils. Cure was affected by air drying for 24 hr at room temperature plus 72 hr at 150 F. These coatings are typically extremely tough and abrasion-resistant, with an absorptance (alpha) of 0.20 and emittance (e) of 0.89. No significant coating damage was observed in the mandrel bend test, even after exposure to thermal cycling from -160 to 160 F. Vacuum exposure of the coatings for 930 hours at 1 equivalent UV sun resulted in no visible degradation and no significant increase in absorptance.

Patterson, W. J.↗
NASA NTRS1979

Development and evaluation of an ablative closeout material for solid rocket booster thermal protection system

A trowellable closeout/repair material designated as MTA-2 was developed and evaluated for use on the Solid Rocket Booster. This material is composed of an epoxy-polysulfide binder and is highly filled with phenolic microballoons for density control and ablative performance. Mechanical property testing and thermal testing were performed in a wind tunnel to simulate the combined Solid Rocket Booster trajectory aeroshear and heating environments. The material is characterized by excellent thermal performance and was used extensively on the Space Shuttle STS-1 and STS-2 flight hardware.

Patterson, W. J.↗
NASA NTRS1979

Strain compatibility assessment for SRB sprayable ablator MSA-1

Tensile and compressive strain compatibility testing was performed on as-sprayed samples of the Shuttle Solid Rocket Booster external ablator material, MSA-1. Strain gages on the aluminum substrate were used to monitor strain. Strain compatibility was determined as the percent strain in the substrate at first visual evidence of MSA-1 failure. The 1/8-in. MSA-1, baselined for large areas of the SRB external skin, was characterized by a strain compatibility of 1.5 to 1.8 percent, which far exceeded the yield range of the metal substrate. Thicker MSA-1 applications (1.4 to 3/8 in.) were characterized by a lower level of strain compatibility, which appeared to be a manifestation of application limitations.

Patterson, W. J.↗
NASA NTRS1977

Control of electro-osmotic flow

Electro-osmotic mobility of glass capillary is sharply reduced by coating of methyl cellulose. Stable protective layer is formed after approximately ten minute exposures to methyl cellulose solution.

Patterson, W. J.↗
NASA NTRS1976

Development of polymeric coatings for control of electro-osmotic flow in ASTP MA-011 electrophoresis technology experiment

The development of a methyl cellulose based coating system for control of electro-osmotic flow at the walls of electrophoresis cells is described. Flight electrophoresis columns were coated with this system, resulting in a flight set of six columns. In flight photography of MA-011 electrophoretic separations verified control of electro-osmotic flow.

Patterson, W. J.↗
NASA NTRS1976

Electrophoresis technology experiment MA-011

Experiment MA-011, electrophoresis technology, was designed to test electrophoresis hardware that would continue the development of technology for electrophoretic separation of materials in the near zero g environment of space. The experimental hardware generally functioned as planned. Frozen live cells were successfully transported into space, electrophoretic processing was performed, and viable cells were returned to earth. A separation of the three types of fixed red blood cells (rabbit, human, and horse) was demonstrated. The human lymphocytes, however, showed no apparent migration. The separation of human kidney cells produced the most exciting data. Analysis shows electrophoretic separation throughout the entire column with at least four bands of viable cells. The isotachophoresis experiment definitely demonstrated the isotachophoretic separation of biological cells in a near zero g environment.

Allen, R. E.↗
NASA NTRS1973

Polymerizable disilanols having in-chain perfluoroalkyl groups

Disilanols containing in-chain perfluoroalkyl and aromatic groups and the process by which they were prepared are discussed. The disilanols, when reacted with a diaminosilane and cured, produce polymeric material resistant to hydrocarbon fuels and stable at elevated temperatures.

Patterson, W. J.↗
NASA NTRS1973

Development and evaluation of polyimide laminates for printed wiring board applications

A developmental and evaluation program on polyimide laminates as printed wiring boards is described. The development of an experimental polyimide with low linear coefficient of thermal expansion normal to the plane of the board is discussed, and its properties are evaluated along with two commercial polyimide printed wiring boards for comparison with the type G-10 epoxy board. Thermal cycling data indicate an urgent need for effectively controlling the expansion normal to the plane of the board in order to minimize solder joint damage.

Patterson, W. J.↗
NASA NTRS1972

Synthesis of temperature and solvent-resistant polymers

Development of silicone polymers, polyimides, and polyisocyanurates for use as insulation, coatings, or adhesives under adverse environmental conditions is discussed. Chemical structure of the organic compounds is presented. Physical and mechanical properties of the compounds are analyzed.

Webster, J. A.↗