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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Heat sealable, flame and abrasion resistant coated fabric

Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.

Tschirch, R. P.↗
NASA NTRS1984

Heat transfer distributions around nominal ice accretion shapes formed on a cylinder in the NASA Lewis icing research tunnel

Local heat transfer coefficients were obtained on irregular cylindrical shapes which typify the accretion of ice on circular cylinders in cross flow. The ice shapes were grown on a 5.1 cm (2.0 in.) diameter cylinder in the NASA Lewis Icing Research Tunnel. The shapes were 2, 5, and 15 min accumulations of glaze ice and 15 min accumulation of rime ice. Heat transfer coefficients were also measured around the cylinder with no ice accretion. These icing shapes were averaged axially to obtain a nominal shape of constant cross section for the heat transfer tests. Heat transfer coefficients around the perimeter of each shape were measured with electrically heated copper strips embedded in the surface of the model which was cast from polyurethane foam. Each strip contained a thermocouple to measure the local surface temperature. The models were run in a 15.2 x 68.6 cm (6 x 27 in.) wind tunnel at several velocities. Background turbulence in the wind tunnel was less than 0.5 percent. The models were also run with a turbulence producing grid which gave about 3.5 percent turbulence at the model location with the model removed. The effect of roughness was also simulated with sand grains glued to the surface. Results are presented as Nusselt number versus angle from the stagnation line for the smooth and rough models for both high and low levels of free stream turblence. Roughness of the surface in the region prior to flow separation plays a major role in determining the heat transfer distribution.

Vanfossen, G. J.↗
NASA NTRS1984

Friction and morphology of magnetic tapes in sliding contact with nickel-zinc ferrite

Friction and morphological studies were conducted with magnetic tapes containing a Ni-Zn ferrite hemispherical pin in laboratory air at a relative humidity of 40 percent and at 23 C. The results indicate that the binder plays a significant role in the friction properties, morphology, and microstructure of the tape. Comparisons were made with four binders: nitrocellulose; poly (vinyledene) chloride; cellulose acetate; and hydroxyl-terminated, low molecular weight polyester added to the base polymer, polyester-polyurethane. The coefficient of friction was lowest for the tape with the nitrocellulose binder and increased in the order hydroxylterminated, low molecular weight polyester resin; poly (vinyledene) chloride; and cellulose acetate. The degree of enclosure of the oxide particles by the binder was highest for hydroxyl-terminated, low molecular weight polyester and decreased in the order cellulose acetate, poly (vinyledene) chloride, and nitrocellulose. The nature of deformation of the tape was a factor in controlling friction. The coefficient of friction under elastic contact conditions was considerably lower than under conditions that produced plastic contacts.

Miyoshi, K.↗
NASA NTRS1983

Clinostat effects on shoot and root of Arabidopsis

In the clinostat environment, Arabidopsis thaliana (L.) Heynh. plants grown in cultures having limited gas exchange with the external atmosphere developed 'above' the agar media a large mass of roots which eventually covered the stem. Cultural conditions were 0.5 rpm, 350 ft.c. from cool white fluorescent lamps, and 25 C. Limited gas exchange culture tubes were covered with Saran Wrap or mylar film, while free gas exchange cultures were plugged with cotton or polyurethane foam. Average shoot-root dry weight ratio of clinostatted, limited gas exchange plants was 3.39 (p less than 0.001) as compared to 10.1 for upright stationary and 10.3 for vertically rotated controls. Average dry weight (48.3 mg) of all clinostatted shoots was greater than those reported by other investigators (15.1 mg). Finally, shoots of the clinostatted plants reported here were almost 2x heavier (p less than 0.01) than the controls (28.7 mg, 26.7 mg), a result contrary to findings of previous investigators, where the clinostatted plants are the lightest (clinostat 15.1 mg, controls 16.5 mg and 17.2 mg).

Hoshizaki, T.↗
NASA NTRS1985

High-Voltage Isolation Transformer

Arcing and field-included surface erosion reduced by electrostatic shields around windings and ferromagnetic core of 80-kilovolt isolation transformer. Fabricated from high-resistivity polyurethane-based material brushed on critical surfaces, shields maintained at approximately half potential difference of windings.

Clatterbuck, C. H.↗
NASA NTRS1985

Static-Suppressing Optical Paint

Electrically conductive flat black paint adheres well to magnesium, aluminum, fiberglass, and other materials. Paint absorbs stray light in optical instruments while preventing buildup of electrostatic fields and arcing. Paint consists of primer and topcoat, both containing electricallyconductive carbon-black powder. Primer two-part epoxy base, and topcoat polyurethane base.

Birnbaum, M. M.↗
NASA NTRS1983

Aircraft surface coatings

A series of studies in which films and liquid spray-on materials were evaluated in the laboratory for transport aircraft external surface coatings are summarized. Elastomeric polyurethanes were found to best meet requirements. Two commercially available products, CAAPCO B-274 and Chemglaze M313, were subjected to further laboratory testing, airline service evaluations, and drag-measurement flight tests. It was found that these coatings were compatible with the severe operating environment of airlines and that coatings reduced airplane drag. An economic analysis indicated significant dollar benefits to airlines from application of the coatings.

Source record↗
NASA NTRS1985

Orbital atomic oxygen effects on thermal control and optical materials - STS-8 results

The effects of exposing 23 specimens of optical and thermal control materials to space at 120 km altitude for over 40 hrs during the STS-8 mission are discussed. Ten samples of paint targeted for the Space Telescope (ST) and the Tethered Satellite were exposed, and included polyurethane, oxide, silicone, and glossy black and white samples which were scanned for alterations in the optical properties after being retrieved. Nine mirror-type materials were also investigated, along with silver specimens typical of solar cell interconnects. The oxygen flow at the orbital altitude was 3.5 x 10 to the 20th atoms/cu cm. The exposures caused no degradation of the magnesium fluoride mirror coatings, while the Kapton coating for the ST solar cell panels showed evidence of losing thickness. The Ag solar cell contacts will require coatings to extend their lifetimes. Overcoatings were also proven necessary for inhibiting degradation of painted surfaces.

Whitaker, A. F.↗
NASA NTRS1986

Improved Joint Design for Box-Stiffened Panels

Mass and strength analyses and system requirements identified titanium-box-stiffened-skin wall candidate for lightweight fuselage of pressurized vehicle. Photoelastic models of stiffener-to-skin joint used to identify quickly modifications to joint that lowers severity of stress concentration. Results with various photoelastic models cut from polyurethane sheet led to novel diffusion-bond joint with reduced stress concentration.

Davis, R. C.↗
NASA NTRS1986

Repairing Foam Insulation

Large holes in polyurethane foam insulation repaired reliably by simple method. Little skill needed to apply method, used for overhead repairs as well as for those in other orientations. Plug positioned in hole to be filled and held in place with mounting fixture. Fresh liquid foam injected through plug to bond it in place. As foam cures and expands, it displaces plug outward. Protrusion later removed.

Corbin, J.↗
NASA NTRS1987

Hardness Tester for Polyur

Rubber-hardness tester modified for use on rigid polyurethane foam. Provides objective basis for evaluation of improvements in foam manufacturing and inspection. Typical acceptance criterion requires minimum hardness reading of 80 on modified tester. With adequate correlation tests, modified tester used to measure indirectly tensile and compressive strengths of foam.

Hauser, D. L.↗
NASA NTRS1988

Silicones As Connector-Potting Compounds

Report evaluates silicone potting materials for electrical connectors. Describes tests of connector specimens made with CV-2510 and DC-6-1104 silicones with dibutyl tin dilaurate catalyst and evaluates test results in light of previously published test results for polyurethanes. Discusses requirements for connector-potting materials, methods used to evaluate silicones, techniques for preparing specimens, and results of tests. Identifies commercial sources of silicone potting materials.

Bouquet, Frank L.↗
NASA NTRS1989

Vacuum Head Checks Foam/Substrate Bonds

Electromechanical inspection system quickly gives measurements indicating adhesion, or lack thereof, between rigid polyurethane foam and aluminum substrate. Does not damage inspected article, easy to operate, and used to perform "go/no-go" evaluations or as supplement to conventional destructive pull-plug testing. Applies vacuum to small area of foam panel and measures distance through which foam pulled into vacuum. Probe head applied to specimen and evacuated through hose to controller/monitor unit. Digital voltmeter in unit reads deflection of LVDT probe head.

Lloyd, James F.↗
NASA NTRS1988

Development of polyisocyanurate pour foam formulation for space shuttle external tank thermal protection system

Four commercially available polyisocyanurate polyurethane spray-foam insulation formulations are used to coat the external tank of the space shuttle. There are several problems associated with these formulations. For example, some do not perform well as pourable closeout/repair systems. Some do not perform well at cryogenic temperatures (poor adhesion to aluminum at liquid nitrogen temperatures). Their thermal stability at elevated temperatures is not adequate. A major defect in all the systems is the lack of detailed chemical information. The formulations are simply supplied to NASA and Martin Marietta, the primary contractor, as components; Part A (isocyanate) and Part B (poly(s) and additives). Because of the lack of chemical information the performance behavior data for the current system, NASA sought the development of a non-proprietary room temperature curable foam insulation. Requirements for the developed system were that it should exhibit equal or better thermal stability both at elevated and cryogenic temperatures with better adhesion to aluminum as compared to the current system. Several formulations were developed that met these requirements, i.e., thermal stability, good pourability, and good bonding to aluminum.

Harvey, James A.↗
NASA NTRS1989

Tissue simulating gel for medical research

A tissue simulating gel and a method for preparing the tissue simulating gel are disclosed. The tissue simulating gel is prepared by a process using water, gelatin, ethylene gylcol, and a cross-linking agent. In order to closely approximate the characteristics of the type of tissue being simulated, other material has been added to change the electrical, sound conducting, and wave scattering properties of the tissue simulating gel. The result of the entire process is a formulation that will not melt at the elevated temperatures involved in hyperthermia medical research. Furthermore, the tissue simulating gel will not support mold or bacterial growth, is of a sufficient mechanical strength to maintain a desired shape without a supporting shell, and is non-hardening and non-drying. Substances were injected into the tissue simulating gel prior to the setting-up thereof just as they could be injected into actual tissue, and the tissue simulating gel is translucent so as to permit visual inspection of its interior. A polyurethane spray often used for coating circuit boards can be applied to the surface of the tissue simulating gel to give a texture similar to human skin, making the tissue simulating gel easier to handle and contributing to its longevity.

Companion, John A.↗
NASA NTRS1991

An overview of the first results on the solar array passive LDEF experiment (sample), AO171

Space environmental effects were visibly obvious on components of experiment AO171 which contained solar cells, composites, polymeric thin films, solar reflectors, protective coatings, metals, paints , and elastomers. Micrometeoroid/space debris impacts were observed on all experiment elements. Luminescence of polyimide, silicone, and polyurethane materials occurred under black light examination. Outgassing of RTV511 occurred mainly as a result of insufficient thermal vacuum bakeout. Solar cell degradation was predominantly below 10 percent. Elastomers lost mass and discolored; composites showed evidence of atomic oxygen attack, and unprotected thin polymer films eroded away.

Whitaker, Ann F.↗
NASA NTRS1992

Silazane to silica

Thin film silica and/or methyl silicone were detected on most external surfaces of the retrieved LDEF. Known sources of silicone in or on the LDEF appear inadequate to explain the ubiquitous presence of the silica and silicone films. Hexamethyldisilazane (HMDS) was used as the Challenger tile waterproofing compound for the Challenger/LDEF deployment mission. HMDS releases NH3 which depolymerizes silicone RTV's. Polyurethanes were also attacked. Much of the silica/silicone contamination of LDEF resulted from HMDS.

Harvey, Gale A.↗
NASA NTRS1991

Qualification of uralane 5750 A/B (LV) for flight applications

Uralane 5750 A/B (LV) is a POLYURETHANE which was to be considered for use as a thin CONFORMAL COATING on printed circuit boards for JPL flight projects. As part of the qualification process several properties of Uralane 5750 A/B (LV) were measured for the as-cured material and after various environmental exposures. The properties that were measured included outgassing i.e. Total Mass Loss (TML) and Vacuum Condensable Mass (VCM) and mass accumulation rates on cold surfaces, Static Elastic Modulus and coefficient of Thermal Expansion (CTE). The Uralane 5750 A/B (LV) that was tested consisted of sheets which varied in both thickness and curing procedures. The environmental exposures consisted of vacuum, thermal and combined thermal vacuum. The physical properties of Uralane 5750 A/B (LV) met the JPL requirements for flight in both the as-cured condition and after environmental exposures.

Lewis, Donald F.↗