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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellulose 7 (2000), S. 177-188 
    ISSN: 1572-882X
    Keywords: cellulose ; dissolution ; selective TEMPO oxidation ; polyglucuronic acid ; NMR spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A series of pseudo amorphous cellulose samples were reacted with catalytic amounts of 2,2,6,6-tetramethyl-1-piperidine oxoammonium salt (TEMPO), sodium hypochlorite and sodium bromide in water. In all samples the primary alcohol groups were selectively oxidised into carboxyl groups, and several water-soluble polyglucuronic acid sodium salts were obtained with different molecular weights. With this reaction system, the degradation of the amorphous cellulose samples may be minimized, provided the oxidation is performed at 4 °C and at constant pH 10, with controlled amounts of TEMPO and sodium hypochlorite.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-06-28
    Description: A program to evaluate liquid oxygen and various hydrocarbon fuel as low cost alternative propellants suitable for future space transportation system applications is discussed. The emphasis of the program is directed toward low earth orbit maneuvering engine and reaction control engine systems. The feasibility of regeneratively cooling an orbit maneuvering thruster was analytically determined over a range of operating conditions from 100 to 1000 psia chamber pressure and 1000 to 10,000-1bF thrust, and specific design points were analyzed in detail for propane, methane, RP-1, ammonia, and ethanol; similar design point studies were performed for a filmcooled reaction control thruster. Heat transfer characteristics of propate were experimentally evaluated in heated tube tests. Forced convection heat transfer coefficients were determined over the range of fluid conditions encompassed by 450 to 1800 psia, -250 to +250 F, and 50 to 150 ft/sec, with wall temperatures from ambient to 1200 F. Seventy-seven hot firing tests were conducted with LOX/propane and LOC/ethanol, for a total duration of nearly 1400 seconds, using both heat sink and water-cooled calorimetric chambers.
    Keywords: PROPELLANTS AND FUELS
    Type: NASA-CR-171713 , NAS 1.26:171713 , REPT-15958-MA-129T-003F-VOL-1
    Format: application/pdf
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  • 3
    Publication Date: 2019-06-28
    Description: An evaluation liquid oxygen (LOX) and various hydrocarbon fuels as low cost alternative propellants suitable for future space transportation system applications was done. The emphasis was directed toward low earth orbit maneuvering engine and reaction control engine systems. The feasibility of regeneratively cooling an orbit maneuvering thruster was analytically determined over a range of operating conditions from 100 to 1000 psia chamber pressure and 1000 to 10,000-1bF thrust, and specific design points were analyzed in detail for propane, methane, RP-1, ammonia, and ethanol; similar design point studies were performed for a film-cooled reaction control thruster. Heat transfer characteristics of propane were experimentally evaluated in heated tube tests. Forced convection heat transfer coefficients were determined. Seventy-seven hot firing tests were conducted with LOX/propane and LOX/ethanol, for a total duration of nearly 1400 seconds, using both heat sink and water-cooled calorimetric chambers. Combustion performance and stability and gas-side heat transfer characteristics were evaluated.
    Keywords: PROPELLANTS AND FUELS
    Type: NASA-CR-171712 , NAS 1.26:171712 , REPT-15958-T-1548-262T-0045
    Format: application/pdf
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