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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Development of an improved membrane for a vapor diffusion water recovery process

Recovery of potable water from urine on manned space missions of extended duration was the objective of work aimed at the improvement of membrane performance for the vapor diffusion process (VDR). Kynar, Teflon, PVC, and polysulfone candidate membranes were evaluated from chemical, thermal, mechanical, and fabricating standpoints to determine their suitability for operation in the VDR pervaporation module. Pervaporation rates and other performance characteristics were determined in a breadboard pervaporator test rig. Kynar and Teflon membranes were demonstrated to be chemically stable at pervaporation temperatures in urine pretreated with chromic acid bactericide. The separation of the pervaporator and condenser modules, the use of a recirculating sweep gas to conduct pervaporate to the condenser, and the selection of a hollow fiber membrane configuration for pervaporator module design is recommended as a result of the investigation.

Rich, T. R.↗
NASA NTRS1974

Auger analysis of films formed on metals in sliding contact with halogenated polymers

The use of Auger electron spectroscopy (AES) to search for transferred polymer must contend with the fact that there has been no published work on Auger analysis of polymers. Since this is a new area for AES, the Auger spectra of polymers and of halogenated polymers in particular is discussed. It is shown that the Auger spectra of halogenated polymers have certain characteristics that permit an assessment of whether a polymeric transfer film has been established by sliding contact. The discussion is general and the concepts should be useful in considering the Auger analysis of any polymer. The polymers chosen for this study are the halogenated polymers polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and polychlorotrifluorethylene (PCTFE).

Pepper, S. V.↗
NASA NTRS1975

Anion selective membrane

Experimental anion permselective membranes were prepared and tested for their suitability as cell separators in a chemical redox power storage system being developed at NASA-Lewis Research Center. The goals of long-term (1000 hr) oxidative and thermal stability at 80 C in FeCl3 and CrCl3 electrolytes were met by most of the weak base and strong base amino exchange groups considered in the program. Good stability is exhibited by several of the membrane substrate resins. These are 'styrene' divinylbenzene copolymer and PVC film. At least four membrane systems produce strong flexible films with electrochemical properties (resistivity, cation transfer) superior to those of the 103QZL, the most promising commercial membrane. The physical and chemical properties of the resins are listed.

Alexander, S. S.↗
NASA NTRS1976

Relative toxicity of pyrolysis products of some synthetic polymers

Nineteen samples of synthetic polymers were evaluated for relative toxicity in the course of characterizing materials intended for aircraft interior applications. The generic polymers included ABS, chlorinated PVC, polycarbonate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyaryl sulfone, polyether sulfone, polybismaleimide, and polyvinyl fluoride. Test results are presented, and compared in relative rankings with similar results on cellulosic materials and other synthetic polymers. Under these test conditions, the samples of synthetic polymers were either comparable to or significantly less toxic than the samples of commercial cellulosic materials.

Hilado, C. J.↗
NASA NTRS1976

Random vibration of compliant wall

The paper is concerned with the realistic case of two-dimensional random motion of a membrane with bending stiffness supported on a viscoelastic spring substrate and on an elastic base plate under both subsonic and supersonic boundary layer turbulence. The cross-power spectral density of surface displacements is solved in terms of design variables of the compliant wall - such as the dimensions and material properties of the membrane (Mylar), substrate (PVC foam), and panel (aluminum) - so that a sensitivity analysis can be made to examine the influence of each design variable on the surface response statistics. Three numerical examples typical of compliant wall design are worked out and their response statistics in relation to wave drag and roughness drag are assessed. The results can serve as a guideline for experimental investigation of the drag reduction concept through the use of a compliant wall.

Yang, J.-N.↗
NASA NTRS1977

Flash fire propensity of materials

Flash fire test results on 86 materials, evaluated using the USF flash fire screening test, are presented. The materials which appear least prone to flash fires are PVC, polyphenylene oxide and sulfide, and polyether and polyaryl sulfone; these did not produce flash fires under these particular test conditions. The principal value of these screening tests at the present time is in identifying materials which appear prone to flash fires, and in identifying which formulations of a generic material are more or less prone to flash fires.

Hilado, C. J.↗
NASA NTRS1978

Adaptation of ion beam technology to microfabrication of solid state devices and transducers

A number of areas were investigated to determine the potential uses of ion beam techniques in the construction of solid state devices and transducers and the packaging of implantable electronics for biomedical applications. The five areas investigated during the past year were: (1) diode-like devices fabricated on textured silicon; (2) a photolithographic technique for patterning ion beam sputtered PVC (polyvinyl chloride); (3) use of sputtered Teflon as a protective coating for implantable pressure sensors; (4) the sputtering of Macor to seal implantable hybrid circuits; and (5) the use of sputtered Teflon to immobilize enzymes.

Topich, J. A.↗
NASA NTRS1978

Relative toxicity of materials in fire situations

The results of toxicity testing of additional materials is presented. Relative toxicity data on polymers by generic type are presented and include wood, polyurethane flexible foam, polyvinyl chloride (PVC), acrylonitrile/butadiene/styrene (ABS), and polyisoprene (natural rubber). A second table gives relative toxicity data on fibers and fabrics including wool, nylon, rayon, polyester, and aromatic polyamide. Sulfur-containing materials seemed to exhibit the shortest times to death of laboratory animals. Some chlorine-containing polymers tended to exhibit shortest time to death also while some halogen-containing polymers gave the shortest time to incapacitation. Among fibers and fabrics, wool, silk, and polyester exhibited the shortest times to incapacitation and times to death. Difficulty in restricting generally accepted materials is discussed and attention is given to other factors important in comparing materials, such as backcoatings and relative weights.

Hilado, C. J.↗
NASA NTRS1982

Self-adaptive closed constrained solution algorithms for nonlinear conduction

Self-adaptive solution algorithms are developed for nonlinear heat conduction problems encountered in analyzing materials for use in high temperature or cryogenic conditions. The nonlinear effects are noted to occur due to convection and radiation effects, as well as temperature-dependent properties of the materials. Incremental successive substitution (ISS) and Newton-Raphson (NR) procedures are treated as extrapolation schemes which have solution projections bounded by a hyperline with an externally applied thermal load vector arising from internal heat generation and boundary conditions. Closed constraints are formulated which improve the efficiency and stability of the procedures by employing closed ellipsoidal surfaces to control the size of successive iterations. Governing equations are defined for nonlinear finite element models, and comparisons are made of results using the the new method and the ISS and NR schemes for epoxy, PVC, and CuGe.

Padovan, J.↗
NASA NTRS1985

Solar-Array Substrate From Glass-Reinforced Concrete

Design elminiates glass superstrate and associated metal framing. Panel has two trapezoidal stiffening ribs for structural support. Strategic placement of ribs with embedded support tubes (standard PVC tubing) minimizes bending moments and resulting stresses produced by installation and windloads. Glass-reinforced concrete panel has smooth flat surface suitable for solar substrate and includes structural bracing for rigidity and design adaptable to mass production.

Eirls, J. L.↗
NASA NTRS1985

Langley Research Center Standard for the Evaluation of Socket Welds

A specification utilized for the nondestructive evaluation of socket type pipe joints at Langley Research Center (LaRC) is discussed. The scope of hardware shall include, but is not limited to, all common pipe fittings: tees, elbows, couplings, caps, and so forth, socket type flanges, unions, and valves. In addition, the exterior weld of slip on flanges shall be inspected using this specification. At the discretion of the design engineer, standard practice engineer, Fracture Mechanics Engineering Section, Pressure Systems Committee, or other authority, four nondestructive evaluation techniques may be utilized exclusively, or in combination, to inspect socket type welds. These techniques are visual, radiographic, magnetic particle, and dye penetrant. Under special circumstances, other techniques (such as eddy current or ultrasonics) may be required and their application shall be guided by the appropriate sections of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (B&PVC).

Berry, R. F., Jr.↗
NASA NTRS1988

Evaluation of flammability for cable-like polymers

A new test method is developed for the flammability of insulated electric cables as well as polymers formed in the cables. The rate of downward flame spread along the polymer surface is measured by a technique in which the flame is stopped at a particular position by winding up the cable at the same speed as the flame spreading rate, with external preheating by an electric furnace having oxidative gas flow. The polymer burns continuously without change of flame condition and the rate is obtained from the winding speed of the cable. A flame spread equation relates the flame spreading rate (V) of the cable-like polymer to O concentration (Yo) and the atmosphere, the preheating temperature, and the pyrolysis temperature for polymer burning. Plotting log V vs. log Yo for experimental results allows evaluation of the flammability of polymers, with discrimination between the effects of O concentration, heating temperature, and specimen shape. Results with various types of PVC electrical cable indicated the validity of the method. Application of the method to the cables in groups showed a flame retardation behavior different from the case of a single cable, in a atmosphere of high O concentration.

Mikado, Tuneo↗
NASA NTRS1988

Safety research of insulating materials of cable for nuclear power generating station

The polymers PE, EPR, PVC, Neoprene, CSP, CLPE, EP and other similar substances are frequently used as insulation and protective covering for cables used in nuclear power generating stations. In order to test these materials for flame retardation, environmental resistance, and cable specifications, they were given the cable normal test, flame test, chemical tests, and subjected to design analysis and loss of coolant accident tests. Material was collected on spark tests and actual experience standards were established through these contributions and technology was accumulated.

Lee, C. K.↗
NASA NTRS1987

Human blood platelets at microgravity

A set of freshly collected and separated human platelet suspensions were transported, in three types of plastic containers, on a 6 day, 2 hr mission of the orbiter Columbia to study the effect of prolonged exposure of human blood cells to microgravity. A controlled environment at a temperature of 22 + or - 1 deg with air flow was provided and another set of samples held on the ground acted as controls. Paired comparisons of platelets at ug versus controls at lxg revealed superior platelet survival at microgravity. When viewed in terms of plastic type, ug platelets in containers fabricated from PVC-TOTM displayed the best overall postflight viability.

Surgenor, D. MACN.↗
NASA NTRS1988

Electrostatic testing of thin plastic materials

Ten thin plastic materials (Velostat, RCAS 1200, Llumalloy, Herculite 80, RCAS 2400, Wrightlon 7000, PVC, Aclar 22A, Mylar, and Polyethylene) were tested for electrostatic properties by four different devices: (1) The static decay meter, (2) the manual triboelectric testing device, (3) the robotic triboelectric testing device, and (4) the resistivity measurement adapter device. The static decay meter measured the electrostatic decay rates in accordance with the Federal Test Method Standard 101B, Method 4046. The manual and the robotic triboelectric devices measured the triboelectric generated peak voltages and the five-second decay voltages in accordance with the criteria for acceptance standards at Kennedy Space Center. The resistivity measurement adapter measured the surface resistivity of each material. An analysis was made to correlate the data among the four testing devices. For the material tested the pass/fail results were compared for the 4046 method and the triboelectric testing devices. For the limited number of materials tested, the relationship between decay rate and surface resistivity was investigated as well as the relationship between triboelectric peak voltage and surface resistivity.

Skinner, S. Ballou↗
NASA NTRS1991

Lock For Valve Stem

Simple, cheap device locks valve stem so its setting cannot be changed by unauthorized people. Device covers valve stem; cover locked in place with standard padlock. Valve lock made of PVC pipe and packing band. Shears, drill or punch, and forming rod only tools needed.

Burley, Richard K.↗
NASA NTRS1992

Rugged Video System For Inspecting Animal Burrows

Video system designed for examining interiors of burrows of gopher tortoises, 5 in. (13 cm) in diameter or greater, to depth of 18 ft. (about 5.5 m), includes video camera, video cassette recorder (VCR), television monitor, control unit, and power supply, all carried in backpack. Polyvinyl chloride (PVC) poles used to maneuver camera into (and out of) burrows, stiff enough to push camera into burrow, but flexible enough to bend around curves. Adult tortoises and other burrow inhabitants observable, young tortoises and such small animals as mice obscured by sand or debris.

Triandafils, Dick↗