Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Alkyls”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Alkyl Pyrocarbonate Electrolyte Additives for Performance Enhancement of Li Ion Cells

Lithium ion rechargeable batteries are being developed for various aerospace applications under a NASA-DoD Interagency program. These applications require further improvements in several areas, specifically in the cycle life for LEO and GEO satellites and in the low temperature performance for the Mars Lander and Rover missions. Accordingly, we have been pursuing research studies to achieve improvement in the low temperature performance, long cycle life and active life of Li ion cells. The studies are mainly focused on electrolytes, to identify newer formulations of new electrolyte additives to enhance Li permeability (at low temperatures) and stability towards the electrode. The latter approach is particularly aimed at the formation suitable SEI (solid electrolyte interphase) on carbon electrodes. In this paper, we report the beneficial effect of using alkyl pyrocarbonates as electrolyte additives to improve the low temperature performance of Li ion cells.

Smart, M. C.↗
NASA NTRS1947

Knock-Limited Power Outputs from a CFR Engine Using Internal Coolants: Four Alkyl Amines, Three Alkanolamines, Six Amides, and Eight Heterocyclic Compounds - 3

An investigation of the antiknock effectiveness of various additive-water solutions when used as internal coolants has been conducted at the NACA Cleveland laboratory. Nine compounds have been previously run in a CFR engine and the results are presented. In an effort to find a good anti-knock-coolant additive with more desirable physical properties than those of the nine compounds previously investigated, water solutions of four alkyl amines, three alkanolamines, six amides, and eight heterocyclic compounds were investigated and the results are presented.

Imming, Harry S.↗
NASA NTRS2009

Lubricated Bearing Lifetimes of a Multiply Alkylated Cyclopentane and a Linear Perfluoropolyether Fluid in Oscillatory Motion at Elevated Temperatures in Ultrahigh Vacuum

Bearing life tests in vacuum with three space liquid lubricants, two multiply alkylated cyclopentanes (MACs) and a linear perfluoropolyether (PFPE) were performed. Test conditions included: an 89 N axial load (mean Hertzian stress 0.66 GPa), vacuum level below 7x10(exp -4) Pa, and a +/-30deg dither angle. Dither rate was 75 cycles per minute. Higher (110 to 122 C) and lower temperature tests (75 C) were performed. For the higher temperature tests, the PFPE, Fomblin (Ausimont SpA) Z25 outperformed Pennzane (Shell Global Solutions) X-2000 by more than an order of magnitude. Lubricant evaporation played a key role in these high temperature results. At 75 C, the order was reversed with both Pennzane X-1000 and X-2000 outperforming Fomblin Z25 by more than an order of magnitude. Most Pennzane tests were suspended without failure. The primary failure mechanism in these lower temperature tests was lubricant consumption in the tribocontacts.

Braza, Joseph↗
NASA NTRS2018

Lifetimes of Multiply Alkylated Cyclopentane Oil in Contact with Various Metals, Evaluated with Vacuum Spiral Orbit Tribometer

The dependence of the lifetimes of small quantities of a Multiply Alkylated Cyclopentane (MAC) lubricant oil, Pennzane (Registered Trademark) 2001A (Nye Lubricants, Inc.), in rolling and sliding contact with different metals was evaluated with a vacuum spiral orbit tribometer. The metals were the bearing alloys 52100 steel, 440C steel, 17-4 PH steel and Nitinol 60 and the elements chromium, vanadium and titanium. The lifetimes of the lubricant oil on different metals fell into distinct groups with 52100 greater than 440C approx. Nitinol 60 greater than 17-4 PH for the order of the lifetimes of the steels and chromium greater than vanadium greater than titanium for the order of the lifetimes for the elements. The limited life of the small quantities of oil is assumed to be due to its consumption by the tribochemical reaction of the oil with the different metal bearing materials. The lifetimes are then inversely related to the reaction rates of the oil molecules with the various metals: the longest life of 52100 steel having the lowest reaction rate and the shortest life of titanium having the highest reaction rate. Mechanisms for the tribochemical reactions are discussed.

lubrication↗
NASA NTRS2022

Phase II and III Solid Waste Management Unit Assessment and Confirmatory Sampling Report for Per- and Polyfluorinated Alkyl Substances, Potential Release Location 237, Kennedy Space Center, Florida

Per- and polyfluoroalkyl substances (PFAS) Phase II and III Solid Waste Management Unit (SWMU) Assessment (SA) and Confirmatory Sampling (CS) were conducted at the John F. Kennedy Space Center (KSC), Potential Release Location (PRL) 237, located in Merritt Island, Brevard County, Florida for the National Aeronautics and Space Administration (NASA) under Contract 80KSC019D0010/80KSC019F0289. A Phase I SA and CS Report was previously submitted that identified 33 locations of concern (LOCs) at KSC associated with the storage, use, or release of materials containing PFAS. The objectives of the Phase II and III SA and CS were to: - Complete site and source characterization of identified LOCs; - Identify areas of potential concern (AOPCs) where past or present activities may have resulted in a release of PFAS to the environment; - Qualitatively characterize migration potential of released PFAS to environmental media (primarily soil, groundwater, surface water, and sediment); and - Identify potential receptors for exposure to PFAS-impacted environmental media. Surface water samples were collected from LOCs/AOPCs and locations on the KSC periphery during PFAS CS Phases I, II and III. Including duplicate samples, 143 environmental samples were analyzed for 14 PFAS compounds and 104 environmental samples were analyzed for 18 PFAS compounds. Ten of the analytes on the 14 compound list were detected at least once in surface water at KSC, with a wide range in magnitude of detections. The State of Florida has surface water screening levels (SWSLs) for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in surface water, both for human and ecological receptors. The human health screening levels are lower than the ecological ones and are used in this report. PFOA was not detected in surface water at concentrations exceeding the SWSL at any LOC or Area of Potential Concern (AOPC). PFOS was detected in surface water at concentrations exceeding the SWSL at 28 LOCs/AOPCs, plus 42 locations on the KSC periphery. The data suggest a wide distribution of PFAS, particularly PFOS, in surface water but the sources of surface water contamination are not yet adequately understood. Sediment samples were collected during Phases II and III but not Phase I. Including duplicate samples, 104 environmental samples were analyzed for 14 PFAS compounds and 10 environmental samples were analyzed for 18 PFAS compounds. Twelve compounds were detected in sediment at KSC, with a wide range in magnitude of detections. There are currently no screening levels or cleanup target levels (CTLs) for sediment. The need to delineate and further characterize PFAS in sediment will be evaluated for those sites that move forward into Site Assessment. Groundwater samples were collected via DPT from LOCs/AOPCs and locations on the KSC periphery during PFAS CS Phases I, II and III. Including duplicate samples, 812 environmental DPT groundwater samples were analyzed for 14 PFAS compounds and 247 environmental samples were analyzed for 18 PFAS compounds. Twelve of the 14 compounds were detected in groundwater at KSC, with a wide range in magnitude of detections. The State of Florida has provisional groundwater cleanup target levels (GCTLs) for PFOA, PFOS and the additive concentration of PFOA+PFOS. PFOA was detected in groundwater at concentrations exceeding its provisional GCTL at 16 LOCs/AOPCs, with no exceedances on the KSC periphery. PFOS was detected in groundwater at concentrations exceeding its provisional GCTL at 30 LOCs/AOPCs, plus two locations on the KSC periphery. PFOA+PFOS was detected in groundwater at concentrations exceeding the provisional GCTL at 31 LOCs/AOPCs, plus two locations on the KSC periphery. Soil samples were collected during Phases II and III but not Phase I. Including duplicate samples, 292 environmental samples were analyzed for 14 PFAS compounds and 80 environmental samples were analyzed for 18 PFAS compounds. Fourteen compounds were detected in soil at KSC, with a wide range in magnitude of detections. The State of Florida has provisional soil cleanup target levels (SCTLs) for PFOA and PFOS. There were no PFOA results above its provisional SCTL. There was one LOC with a result above the provisional SCTL for residential settings. Recommendations are presented for each LOC and AOPC.

PFAS↗
NASA NTRS1975

Alkyl substituted cyclic ethers in 2,300 M yr old Transvaal algal stromatolite

Two cyclic ethers have been identified for the first time from insoluble polymer-like kerogen in a Precambrian rock by ozonolysis, gas chromatography, and mass spectrometry. The ethers are 2-n-propyl-3-methyltetrahydrofuran and 2-n-propyltetrahydropyran. These compounds could prove to be the oldest indigenous biochemical fossils. The sample was obtained 750 m stratigraphically above the base of the Transvaal Sequence from an outcrop approximately 315 km north-east of Johannesburg, South Africa.

Zumberge, J. E.↗
NASA NTRS1970

Nuclear alkylated pyridine aldehyde polymers and conductive compositions thereof

A thermally stable, relatively conductive polymer was disclosed. The polymer was synthesized by condensing in the presence of catalyst a 2, 4, or 6 nuclear alklylated 2, 3, or 4 pyridine aldehyde or quaternary derivatives thereof to form a polymer. The pyridine groups were liked by olefinic groups between 2-4, 2-6, 2-3, 3-4, 3-6 or 4-6 positions. Conductive compositions were prepared by dissolving the quaternary polymer and an organic charge transfer complexing agent such as TCNQ in a mutual solvent such as methanol.

Rembaum, A.↗
NASA NTRS1982

Use of column V alkyls in organometallic vapor phase epitaxy (OMVPE)

The use of the column V-trialkyls trimethylarsenic (TMAs) and trimethylantimony (TMSb) for the organometallic vapor phase epitaxy (OM-VPE) of III-V compound semiconductors is reviewed. A general discussion of the interaction chemistry of common Group III and Group V reactants is presented. The practical application of TMSb and TMAs for OM-VPE is demonstrated using the growth of GaSb, GaAs(1-y)Sb(y), Al(x)Ga(1-x)Sb, and Ga(1-x)In(x)As as examples.

Ludowise, M. J.↗
NASA NTRS1989

Acidic attack of perfluorinated alkyl ether lubricant molecules by metal oxide surfaces

The reactions of linear perfluoropolyalkylether (PFAE) lubricants with alpha-Fe2O3 and Fe2O3-based solid superacids were studied. The reaction with alpha-Fe2O3 proceeds in two stages. The first stage is an initial slow catalytic decomposition of the fluid. This reaction releases reactive gaseous products which attach the metal oxide and convert it to FeF3. The second stage is a more rapid decomposition of the fluid, effected by the surface FeF3. A study of the inital breakdown step was performed using alpha-Fe2O3, alpha-Fe2O3 preconverted to FeF3, and sulfate-promoted alpha-Fe2O3 superacids. The results indicate that the breakdown reaction involves acidic attack at fluorine atoms on acetal carbons in the linear PFAE. Possible approaches to combat the problem are outlined.

Zehe, Michael J.↗
NASA NTRS1990

Acidic attack of perfluorinated alkyl ether lubricant molecules by metal oxide surfaces

The reactions of linear perfluoropolyalkylether (PFAE) lubricants with alpha-Fe203 and Fe203-based solid superacids were studied. The reaction with alpha-Fe203 proceeds in two stages. The first stage is an initial slow catalytic decomposition of the fluid. This reaction releases reactive gaseous products which attach the metal oxide and convert it to FeF3. The second stage is a more rapid decomposition of the fluid, effected by the surface FeF3. A study of the initial breakdown step was performed using alpha-Fe203, alpha-Fe203 preconverted to FeF3, and sulfate-promoted alpha-Fe203 superacids. The results indicate that the breakdown reaction involves acidic attack at fluorine atoms on acetal carbons in the linear PFAE. Possible approaches to combat the problem are outlined.

Zehe, Michael J.↗
NASA NTRS1991

Kinetics of the reactions of alkyl radicals with HBr and DBr

The kinetics of the reactions CH3 + HBr, CD3 + HBr, CH3 + DBr, C2H5 + HBr, C2H5 + DBr, t-C4H9 + HBr, and t-C4H9 + DBr is studied as a function of temperature (257-430 K) and pressure (10-300 Torr of N2). Time-resolved resonance fluorescence detection of Br atom appearance following laser flash photolysis of RI was used in the experiments. Results show that the rates of all reactions increased as the temperature decreased.

Nicovich, J. M.↗