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  • LUNAR AND PLANETARY EXPLORATION  (7)
  • Chemistry  (3)
  • vibrating wire  (2)
  • polymer  (1)
Collection
Keywords
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    Injection moulding of thermoplastics: Freezing during mould filling (1983)
    Springer
    Rheologica acta 22 (1983), S. 223-236 
    Details
    ISSN: 1435-1528
    Keywords: Injection moulding ; thermoplastic ; freezing ; polymer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The injection moulding of thermoplastic polymers involves, during mould filling, flows of hot melts into mould networks, the walls of which are so cold that frozen layers form on them. Theoretical analyses of such flows are presented here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01332374
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A vibrating-rod densimeter (1989)
    Springer
    International journal of thermophysics 10 (1989), S. 871-883 
    Details
    ISSN: 1572-9567
    Keywords: densimeter ; density ; high pressure ; n-heptane ; vibrating wire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements are reported that confirm the applicability of the theory of a vibrating-rod densimeter to a practical instrument. It is demonstrated that with such a device, liquid density measurements evaluated on an absolute basis can be made with an accuracy of ±0.2% at pressures up to 100 MPa. When the density of the liquid is evaluated on a relative basis, a precision of ±0.1% can be achieved over the same range of pressure. Future developments of the instrument that would greatly enhance its sensitivity and that rely upon the availability of a proven theory are therefore now possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00514482
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    An absolute vibrating-wire viscometer for liquids at high pressures (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 231-244 
    Details
    ISSN: 1572-9567
    Keywords: high pressure ; n-hexane ; vibrating wire ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The design and operation of a new vibrating-wire viscometer for the measurement of the viscosity of liquids at pressures up to 100 MPa are described. The design of the instrument is based on a complete theory so that it is possible to make absolute measurements with an associated error of only a few parts in one thousand. Absolute measurements of the viscosity of n-hexane are reported at 298.15 K at pressures up to 80 MPa. The overall uncertainty in the reported viscosity data is estimated to be ±0.5%, an estimate confirmed by the comparison of values of viscosity of slightly inferior accuracy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500749
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Rotary injection reaction injection molding (RI-RIM). Part II: Interfacial segregation of release systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 175-186 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This paper describes the shear imposed interfacial segregation of release systems for the facilitated attenuation of polyurethane (PU) adhesion to metal coun-terfaces using a RI-RIM system. It is shown that the migration rate of the dispersed release additives due to a shear imposed stress in the resin fluid is much greater than that arising from Fickian diffusion, thereby removing a vital constraint from conventional practice. The novel rotary injection RIM system is presented to simulate the on-line injection and shear induced interfacial segregation in model PU/abherent systems. A wide range of recipes comprising single (liquids or solids) and multicomponent (liquid-liquid and solid-liquid) release materials were injected into the polymerizing resin mixture to provide cohesively weak and friable “particle” boundary layer assemblies at the PU/metal interface. An instrumented Blister Test was employed to evaluate the quality of the molded interfaces in terms of adhesion and the concentration distribution of the injected species in the final cured moldings was determined through high pressure liquid chromatography (HPLC). A comparison of the results on the shear modified and the compounded interfaces confirm an accentuated lateral migration of the additives to the interface resulting in an appreciable diminution in the adhesion of the system. Finally, transport models are suggested to account for the observed augmented transport.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300307
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Rotary injection reaction injection molding (RI-RIM). Part I: Basic design features (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 162-174 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This paper describes the basic design features of a new reaction injection molding (RIM) processing device, Rotary Injection RIM (RI-RIM). The new design includes a novel mixing concept which furnishes high intermaterial contact area upon shear imposed rotary injection of the RIM components for effective in situ polymerization. This system operates in low pressure and laminar flow conditions, as opposed to the high pressure and turbulent flow, found in conventional RIM systems. The mixing process is described and quantified in terms of the various forces which govern the injection process. A progressive diminution in the average size of the dispersions generated is found with increasing rate of shear, continuous-phase viscosity, and injection rate. These results are compared with those expected from traditional shear mixing (bulk convective shearing) under comparable conditions and the current system found to be more efficacious. Reaction molding experiments with RI-RIM using a model polyurethane system are described and the influence of operating conditions on the mechanical properties of the finished moldings are elucidated. A detectable change in the morphology of the system is observed following increase in the total shear strain imparted to the initial mix of the multiphase reactants. It is suggested that the observed change is affected by a segregation between the components of the segmented polymer.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300306
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  • 6
    Electronic Resource
    Electronic Resource
    Simulation of reacting flow during filling in reaction injection molding (RIM) (1986)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 1264-1275 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This paper deals with computer simulation of the filling stage of the Reaction Injection Molding (RIM) process for cavities of rectangular, cylindrical, and disc shapes. The computer model is in two parts: the main flow and the flow by the moving front. In the main flow part, the transient equations of axial momentum, energy and species conservation and also the continuity equation are solved numerically by finite-difference methods using a moving, changing mesh. In the flow front part, which is quite novel, the transient (parabolic) vorticity, energy and species conservation equations and the elliptic streamfunction equation are again solved by finite-difference methods. An important feature of both parts is that convection along and across the flow is included in all the transient equations. Results are presented for all three cavity shapes and those for rectangular cavities are compared with the experimental results of previous investigators.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760261806
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  • 7
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    Water loss from Venus: Implications for the Earth's early atmosphere (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The atmosphere of Venus outgassed rapidly as a result of planetary heating during accretion, resulting in massive water loss. The processes affecting atmospheric chemistry following accretion have consisted largely of hydrogen escape and internal re-equilibrium. The initial bulk composition of Venus and Earth are assumed to have been roughly similar. Chemical speciation on Venus was controlled by the temperature and oxygen buffering capacity of the surface magma. It is also assumed that the surfaces of planetary bodies of the inner solar system were partly or wholly molten during accretion with a temperature estimated at 1273 to 1573 K. To investigate the range of reasonable initial atmospheric compositions on Venus, limits have to be set for the proportion of total hydrogen and the buffered fugacity of oxygen. Using the C/H ratio of 0.033 set for Earth, virtually all of the water generated during outgassing must later have been lost in order to bring the current CO2/H2O ratio for Venus up to its observed value of 10 sup 4 to 10 sup 5. The proportion of H2O decreases in model atmospheres with successfully higher C/H values, ultimately approaching the depleted values currently observed on Venus. Increasing C/H also results in a rapid increase in CO/H2O and provides an efficient mechanism for water loss by the reaction CO+H2O = CO2 + H2. This reaction, plus water loss mechanisms involving crustal iron, could have removed a very large volume of water from the Venusian atmosphere, even at a low C/H value.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 65-67
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    NASA TECHNICAL REPORTS
  • 8
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    The case for a wet, warm climate on early Mars (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Arguments are presented in support of the idea that Mars possessed a dense CO2 atmosphere and a wet, warm climate early in its history. The plausibility of a CO2 greenhouse is tested by formulating a simple model of the CO2 geochemical cycle on early Mars. By scaling the rate of silicate weathering on Earth, researchers estimated a weathering time constant of the order of several times 10 to the 7th power years for early Mars. Thus, a dense atmosphere could have existed for a geologically significant time period (approx. 10 to the 9th power years) only if atmospheric CO2 was being continuously resupplied. The most likely mechanism by which this could have been accomplished is the thermal decomposition of carbonate rocks induced directly or indirectly by intense, global scale volcanism.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 160
    Format: application/pdf
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  • 9
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    The case for a wet, warm climate on early Mars (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The conditions under which Mars could have had a warm wet climate during its early evolution are explored by means of numerical simulations, incorporating more accurate data on the opacity of gaseous CO2 and H2O in the solar and thermal spectral regions (McClatchey et al., 1971) into the one-dimensional radiative-convective greenhouse model of Kasting and Ackerman (1986). The results are presented in extensive graphs and characterized in detail, with consideration of atmospheric CO2 loss rates, sources of atmospheric CO2, CO2 partitioning between atmosphere and hydrosphere, the Mars volatile inventory, the CO2 geochemical cycle, climate evolution, and observational tests. It is concluded that greenhouse conditions (requiring atmospheric CO2 of 1-5 bar) could have existed for a period of about 1 Gyr if the total surficial inventory of CO2 was 2-10 bar.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 71; 203-224
    Format: text
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  • 10
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    Water loss on Venus - The role of carbon monoxide (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The four-to-fivefold difference in water abundance between the earth and Venus may reflect either initial differences in the bulk volatile content of the two planets, or massive water loss mechanisms on Venus. These two possibilities were investigated by performing thermodynamic calculations on the heterogeneous system C-O-H-N-S, varying C/H upward from its 0.033 terrestrial value. While atmospheric H2O decreases as bulk C/H increases, the latter would have to rise to an improbably high value in order to account for the low water abundance on Venus through initial deficiency alone. Calculations suggest that if the outgassed C/H on Venus was higher than on earth by even a factor of 5, it would have been sufficient for CO to become competitive with FeO as a sink for oxygen. Together with the lower initial water abundance value that follows from a higher C/H ratio, water loss due to CO may have been a major factor.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 60; 307-316
    Format: text
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