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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Polyimide resin composites via in situ polymerization of monomeric reactants

Thermo-oxidatively stable polyimide/graphite-fiber composites were prepared using a unique in situ polymerization of monomeric reactants directly on reinforcing fibers. This was accomplished by using an aromatic diamine and two ester-acids in a methyl alcohol solvent, rather than a previously synthesized prepolymer varnish, as with other A-type polyimides. A die molding procedure was developed and a composite property characterization conducted with high modulus graphite fiber tow. Flexure, tensile, compressive, and shear tests were conducted at temperatures from 72 to 650 F on laminates before and after exposures at the given temperatures in an air environment for times up to 1000 hours. The composite material was determined to be oxidatively, thermally, and hydrolytically stable.

Cavano, P. J.↗
NASA NTRS1974

Interstellar molecules - Origin by catalytic reactions on grain surfaces

To determine the compound distribution formed by surface catalysis, mixtures of CO, D2, and ND2 were heated with nickel-iron or montmorillonite clay catalysts for 49-214 hours at 250 to 300 C. Compounds identified include most of the known polyatomic interstellar molecules, as well as homologous series of acetylenes, dienes, alcohols, aldehydes, ketones, ethers, esters, nitriles, amines, etc., and cyclic compounds such as furans and pyrroles. These homologous series are uniquely characteristic of surface catalysis. A search for the heavier members of these series, predicted to occur at 1/10th to 1/1,000th the abundance of the lightest members, thus comprises a crucial test of this mechanism.

Anders, E.↗
NASA NTRS1975

Monitoring spacecraft atmosphere contaminants by laser absorption spectroscopy

Data were obtained which will provide a test of the accuracy of the differential absorption method for trace contaminant detection in many-component gas mixtures. The necessary accurate absorption coefficient determinations were carried out for several gases; acetonitrile, 1,2-dichloroethane, Freon-113, furan, methyl ethyl ketone, and t-butyl alcohol. The absorption coefficients are displayed graphically. An opto-acoustic method was tested for measuring absorbance, similar to the system described by Dewey.

Steinfeld, J. I.↗
NASA NTRS1974

Polyimide adhesives

A process of preparing aromatic polyamide-acids for use as adhesives is described. An equimolar quantity of an aromatic dianhydride is added to a stirred solution of an aromatic diamine in a water or alcohol-miscible ether solvent to obtain a viscous polymer solution. The polymeric-acid intermediate polymer does not become insoluble but directly forms a smooth viscous polymer solution. These polyamic-acid polymers are converted, by heating in the range of 200-300 C and with pressure, to form polyimides with excellent adhesive properties.

Progar, D. J.↗
NASA NTRS1974

O/1 D/ production in ozone photolysis near 3100 A

Relative quantum yields of O(1 D) production in ozone photolysis from 2750 to 3340 A have been determined in the gas phase at -40 C. The O(1 D) was monitored by means of its reaction with isobutane to form isobutyl alcohol. The light source was a high pressure mercury lamp combined with a monochromator, with a bandwidth of 16 A. The results show a constant O(1 D) production below 3000 A, which is taken as unity on the basis of previous work. There is a very sharp fall-off in O(1 D) production which is centered at 3080 A. At 3130 A, O(1 D) production is not greater than 0.1.

Lin, C.-L.↗
NASA NTRS1975

Combustion intensity and distribution relation to noise generation

Experiments with several different flame holder geometries were conducted to investigate the degree to which combustion roughness can be altered by altering the flame intensity and flame distribution in a ducted combustion system. The effect of admitting primary air through a plane-slotted or a slotted-swirl vane flame holder was compared and the combustion roughness and noise was contrasted with that obtained with a closed front-end perforated can. The slotted front-end burners produced much smoother burning and less noise than the closed front-end can. No advantage was apparent with swirl vs nonswirl when approximately the same inlet flow distribution was maintained. Preheated inlet air provided somewhat smoother combustion as compared with ambient temperature air. The combustion roughness with methyl alcohol was briefly compared with that of isooctane; indications are that it burns more smoothly, but more detailed studies are needed to substantiate these indications.

Plett, E. G.↗
NASA NTRS1975

Flat-plate /vapor-chamber/ heat pipes

This paper discusses the design, fabrication and testing of heat pipes constructed in the form of flat-plate panels. The test panels were constructed of copper with methyl alcohol as the working fluid. Capillary grooves etched on the internal surfaces provided evaporation and condensation heat-transfer coefficients on the order of 1600 Btu/hr-sq ft-deg F. Two panels were launched on board a sounding rocket; the payload reached an altitude of 140 miles, and zero gravity was achieved for almost six minutes. The panel with working fluid inside demonstrated a heat input flux of 2.5 watts/sq cm, with only a 3 to 5 C temperature difference throughout the entire panel.

Fleischman, G. L.↗
NASA NTRS1975

Improvement in oxidation resistance of the leading edge thermal protection for a space shuttle

To improve the oxidation resistance of a carbon-carbon composite, impregnations were performed using pitches, polyfurfuryl alcohols, and phenolic resins, including a silicon-doped phenolic resin. Oxidation resistance and strength increased for all of the composites as the impregnant-carbon residue increased. The properties of the composites impregnated with the nonsilicon-bearing resins were nearly identical and depended only on the amount of impregnant residue present. However, for equivalent residue concentrations, composites produced with the silicon-bearing resin gave higher strengths and at least 100% better oxidation resistance than was observed for the other composites or for a prototype control material.

Williams, J. M.↗
NASA NTRS1975

Volatile organic components in the Skylab 4 spacecraft atmosphere

The volatile organic components in the spacecraft cabin atmosphere of Skylab 4 were trapped on a solid adsorbent at various times during the mission. In post-flight analyses, more than 300 compounds in concentrations from less than 1 ppb up to 8000 ppb could be detected by high-resolution gas chromatography. In the samples of the 11th, 47th, and 77th day of the mission, approximately 100 components in the molecular weight range from 58 to 592 were identified by mass spectrometry. Besides components known from other environments, such as alkanes, alkenes, and alkylated aromatic hydrocarbons, components typical of the human metabolism, such as ketones and alcohols, were found. Other typical components in the spacecraft atmosphere included fluorocarbons and various silicone compounds, mostly normal and cyclic methylsiloxanes.

Liebich, H. M.↗
NASA NTRS1974

Vestibular ataxia and its measurement in man

Methods involved in and results obtained with a new comprehensive ataxia test battery are described, and definitions of spontaneous and induced vestibular ataxia in man are given in terms of these findings. In addition, the topic of alcohol-induced ataxia in relation to labyrinth function is investigated. Items in the test battery comprise a sharpened Romberg test, in which the subject stands on the floor with eyes closed and arms folded against his chest, feet heel-to-toe, for 60 seconds; an eyes-open walking test; an eyes-open standing test; an eyes-closed standing test; an eyes-closed on-leg standing test; an eyes-closed walk a line test; an eyes-closed heel-to-toe walking test; and supplementary ataxia tests such as the classical Romberg test.

Fregly, A. R.↗
NASA NTRS1976

Stripper for silicone polymers

Potassium hydroxide in ethyl alcohol solution can strip away coatings, adhesives, and encapsulants without damaging substrates.

Williams, B. B.↗
NASA NTRS1974

Combustion generated noise in gas turbine combustors

Experiments were conducted to determine the noise power and spectra emitted from a gas turbine combustor can exhausting to the atmosphere. Limited hot wire measurements were made of the cold flow turbulence level and spectra within the can. The fuels used were JP-4, acetone and methyl alcohol burning with air at atmospheric pressure. The experimental results show that for a fixed fuel the noise output is dominated by the airflow rate and not the fuel/air ratio. The spectra are dominated by the spectra of the cold flow turbulence spectra which were invariant with airflow rate in the experiments. The effect of fuel type on the noise power output was primarily through the heat of combustion and not the reactivity. A theory of combustion noise based upon the flame radiating to open surroundings is able to reasonably explain the observed results. A thermoacoustic efficiency for noise radiation as high as .00003 was observed in this program for JP-4 fuel. Scaling rules are presented for installed configurations.

Strahle, W. C.↗
NASA NTRS1975

The development of low temperature curing adhesives

An approach for the development of a practical low temperature (293 K-311 K/68 F-100 F) curing adhesive system based on a family of amide/ester resins was studied and demonstrated. The work was conducted on resin optimization and adhesive compounding studies. An improved preparative method was demonstrated which involved the reaction of an amine-alcohol precursor, in a DMF solution with acid chloride. Experimental studies indicated that an adhesive formulation containing aluminum powder provided the best performance when used in conjunction with a commercial primer.

Green, H. E.↗
NASA NTRS1976

Advanced prototype automated iodine monitor system

The technique of detecting and measuring parts-per-million concentrations of aqueous iodine by direct spectrophotometric means is discussed, and development of a prototype Automated Iodine Monitoring/Controller System (AIMS) is elaborated. The present effort is directed primarily toward reducing the power requirement and the weight of the AIMS. Other objectives include determining the maximum concentration of iodine that can be dissolved in an alcohol solution, and in an aqueous potassium iodide solution. Also discussed are the effects of a no flow condition on iodine measurements and the effect of pH on spectrophotometric iodine determinations.

Source record↗
NASA NTRS1976

Performance characteristics of rotating wickless heat pipes

A theoretical model was derived for laminar film condensation on the inside of a rotating, truncated cone which includes the effects of vapor shear and vapor pressure drop. Results are compared to those of previous investigations. Experimental data are presented for rotational speeds of 700, 1,400, 2,100, and 2,800 rpm using water, ethyl alcohol, and Freon 113 as working fluids. Agreement between theory and experiment is within + or - 20 percent.

Marto, P. J.↗
NASA NTRS1975

Diffusion in mixed solvents. II - The heat of mixing parameter

Correlation of second-order rate constants for many reactions involving electron transfer between organic molecules, solvated electron reactions, iodine diffusion coefficients, and triplet state electron transfer reactions has been made with the heat of mixing parameter (HMP) for the aqueous binary solvent systems. The aqueous binary solvents studied are those containing methanol or ethanol (type I solvent); 1-propanol or tert-butyl alcohol (type II solvent); or sucrose or glycerol (type III solvent). A plot of the HMP vs. the diffusion parameter for each reaction yields superimposable curves for these reactions in a particular solvent mixture over the entire solvent mixture range, irrespective of the value of the reaction's rate constant or diffusion coefficient in water.

Carapellucci, P. A.↗
NASA NTRS1975

Nuclear magnetic resonance study of thermal oxidation of polyisoprene

An investigation was conducted concerning the microstructural changes occurring in cis- and trans-1,4-polyisoprenes during uncatalized thermal oxidation in the solid phase. The investigation made use of approaches based on proton and carbon-13 NMR spectroscopy. The oxidation of squalene and dihydromyrcene in the liquid phase was also studied. The studies provide the first NMR spectroscopic evidence for the presence of epoxy and peroxide, hydroperoxide, and alcohol groups within the oxidized polyisoprene chain.

Golub, M. A.↗
NASA NTRS1976

Interstellar molecules

Progress in the discovery and study of interstellar molecules is summarized. The 36 molecular species thus far identified in interstellar space are listed in several groups which include simple hydrides, oxides, and sulfides, various derivatives of ammonia, molecules involving linear carbon chains, cyanides, and molecules related in structure to formaldehyde, alcohols, or ethers. Several free radicals are described, the discovery of molecules in external galaxies is discussed, and possible mechanisms for molecular formation are noted. Methods for examining relative isotopic abundances by measuring molecules in interstellar clouds are outlined, mechanisms for the excitation of interstellar molecules are reviewed, and values are presented for the C-12/C-13 abundance ratio in a number of interstellar clouds. The detection of interstellar masers is discussed along with pumping mechanisms and masing transitions in H2CO, CH, OH, and SiO. The nature of dense interstellar clouds is examined in terms of several simple and complex cloud models, with emphasis on multiple condensation models.

Townes, C. H.↗