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  • 1
    Electronic Resource
    Electronic Resource
    Cure kinetics of an epoxy-novolac molding compound (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1271-1280 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The cure reaction of an epoxy-novolac molding compound was studied by means of differential scanning calorimetry using the dynamic (i.e., temperature scanning) approach. Based on a modified version of Friedman's method, a procedure aiming at the phenomenological description of cure kinetics was developed. This method was found capable of following satisfactorily the thermokinetics of the molding compound. Our results indicate that the cure reaction is autocatalytic in nature and does not follow simple nth-order kinetics.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410535
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cure behavior of an epoxy-novolac molding compound (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 165-172 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The isothermal cure of an epoxy-novolac molding compound was studied by means of differential scanning calorimetry (DSC). The glass transition temperature (Tg) of the molding compound increased in an approximately linear manner with conversion (α) during the major part of the cure process. Predictions of an empirical kinetic scheme (established earlier from dynamic DSC results) compared favorably with the present isothermal results in the absence of vitrification. In combination with the gel point conversion (αgel) determined via dynamic rheological analysis and gravimetric measurements, our DSC results indicated that gelation bears no apparent effect on the rate of cure whereas vitrification retards the cure reaction. Based on the measured αgel, the approximate Tg-α relationship, and the thermokinetic results, the time-temperature-transformation diagram of this molding compound was constructed and discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440118
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  • 3
    Electronic Resource
    Electronic Resource
    Vinyl monomer irradiation-grafted nylon 4 membranes (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 4709-4718 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: To improve the performance of Nylon 4 membranes, this study attempts to utilize 60Co γ-ray irradiation which induces vinyl monomers to be grafted onto Nylon 4 membranes for desalination purposes. Sodium styrene sulfonate, acrylamide, vinylacetate, and styrene are the grafting monomers. The transport properties and mechanical strength of the γ-ray irradiation-grafted Nylon 4 membranes are studied. Both the water flux and salt rejection of sodium styrene sulfonate-grafted membranes increase significantly, compared to Huang's results. The other grafted membranes also show increased salt rejection.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320435
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  • 4
    Electronic Resource
    Electronic Resource
    2-Hydroxyethyl methacrylate-terminated polyurethane/polyurethane interpenetrating polymer networks (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 34 (1997), S. 261-268 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interpenetrating polymer networks (IPNs) of polyurethane (PU) and 2-hydroxyethyl methacrylate (MEHA)-terminated polyurethane (HPU) were prepared by solution polymerization. PU prepolymer was synthesized from 4,4-diphenyl methane diisocyanate (MDI) and poly(propylene oxide) glycol (PPG). HPU prepolymer was synthesized from MDI, poly(tetramethylene oxide) glycol and HEMA. Dynamic mechanical analysis showed that the resultant IPN membranes have good compatibility between their constituents. As the HPU content increased, the tensile strength of the IPNs first increased and then decreased. For the highest tensile strength, the optimum HPU content was about 25 wt %. The value of surface tension of IPNs varied from 44.4 to 50.5 dyne/cm, and polarity ranged from 0.59 to 0.91. The relative index of platelet adhesion (RIPA) of the IPN membranes was measured by the dynamic thrombosis test at constant shaking speed and temperature. By the criteria of this test, the IPN membranes with HPU content of about 25 wt % have the minimum platelet adhesion. When measured by the angular dependent ESCA technique on the surface of IPN samples, the variation in the RIPA correlated to the change in the surface soft segment to hard segment ratio. Higher HPU content resulted in more migration of soft segments toward the surface. The platelet adhesion was observed to be minimized when the surface O/N ratio was around 12. © 1997 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 5
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    Nuclear safety considerations in the conceptual design of a fast reactor for space electric power and propulsion (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Some nuclear safety aspects of a 3.2 mWt heat pipe cooled fast reactor with out-of-core thermionic converters are discussed. Safety related characteristics of the design including a thin layer of B4C surrounding the core, the use of heat pipes and BeO reflector assembly, the elimination of fuel element bowing, etc., are highlighted. Potential supercriticality hazards and countermeasures are considered. Impacts of some safety guidelines of space transportation system are also briefly discussed, since the currently developing space shuttle would be used as the primary launch vehicle for the nuclear electric propulsion spacecraft.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-492 , Conference on the Future of Aerospace Power Systems; Mar 01, 1977 - Mar 03, 1977; St. Louis, MO
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Nuclear thermionic power system for spacecraft (1976)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Mission studies have shown that nuclear electric propulsion is necessary for providing the needed propulsion system for detailed outer planet exploration. The study is centered around thermionic conversion based on an out-of-core approach employing heat pipes to thermally couple the nuclear reactor with the thermionic converters. Emphasis is on a parametric study to size a 500 kWe thermionic power conversion system suitable for a single shuttle launch. It is shown that out-of-core thermionic conversion results in a large L/D system that produces minimum weight. This evolving thermionic technology is compatible with developing insulator technology allowing operation at temperatures compatible with both molybdenum and insulators while retaining a sufficiently high heat rejection temperature to minimize radiator size and weight.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Conference on Intersociety Energy Conversion Engineering; Sep 12, 1976 - Sep 17, 1976; State Line, NV
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Nuclear power source for electric propulsion (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A low specific weight (20 to 40 Kg/Kwe), long life (6 to 10 year), 100 to 400 KWe nuclear electric propulsion (NEP) system can deliver 2,000 to 10,000 Kg payloads for intensive study of our solar system. The nuclear power source is about 80% of the NEP system mass, thus the NASA program is focused on developing the power source technology. Because of the long life requirements, direct thermal to electric energy conversion technology (thermionic and thermoelectric) is being pursued. In order to meet the low specific weight it is necessary to develop a 10 to 15% conversion module with a 875 K minimum heat rejection temperature and a 1675 K maximum input temperature. The thermoionic converter is about 9% efficient at these temperatures. The thermoelectric converter is limited to a 1300 K input temperature. So, the thermionic program is focused on improving the efficiency while the thermoelectric program is focused on increasing the temperature.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-2088 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
    Format: text
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  • 8
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    An improved thermionic power conversion system for space propulsion (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A concept of an out-of-core thermionic nuclear electric power conversion system for 400 Kwe power level is being investigated for space propulsion applications. Two key features distinguish the power system design from previous thermionic power conversion concepts. First, the thermionic converters are located outside a nuclear reactor with a neutron shield inserted to reduce the radiation level on the thermionic converter matrix. Second, multiple liquid-metal heat pipes are used exclusively for both thermal power transport (from the nuclear reactor to the thermionic converters) and waste heat removal (from the thermionic converters to the space radiator); no mechanical or electromagnetic pumps are involved. The system characteristics are are compared to those of the in-core thermionic reactor system concept. In many aspects, the system characteristics, including specific weight, lifetime, dynamics control and safety features are found to be more desirable than those of the in-core system concept.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: Intersociety Energy Conversion Engineering Conference; Aug 20, 1978 - Aug 25, 1978; San Diego, CA
    Format: text
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