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  • 1
    Electronic Resource
    Electronic Resource
    Phase behavior of hydrogen-light-hydrocarbon systems (1957)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 3 (1957), S. 236-241 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The decreasing solubility of hydrogen in hydrocarbons with decreasing temperature continues down to the freezing point of the hydrocarbons, around -300°F. This behavior is shown to be an enlargement of phenomena exhibited by normal hydrocarbon mixtures. Methods of predicting equilibrium-phase compositions are presented for hydrogen in ligh-hydrocarbon systems. The correlations are satisfactory for binary and certain ternary systems, but are not reliable for complex mixtures.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690030219
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  • 2
    Electronic Resource
    Electronic Resource
    Manufacture of urea-formaldehyde concentrates using a gas-liquid technology (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1245-1248 
    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: The performance of a laboratory packed-column for the manufacture of urea-formaldehyde (UF) concentrates is analyzed. Gaseous formaldehyde was generated by the thermal decomposition of paraformaldehyde in a carrier nitrogen stream. The UF solution was continuously recirculated through a glass column filled with Raschig rings. No pH control was necessary when the operation was started using a solution with a F/U molar ratio higher than 3.5 to 4. Otherwise, insoluble resins appeared during the operation. The formaldehyde absorption rate was controlled by the gas phase resistance. The vapor composition in equilibrium with a typical UF concentrate is provided as a function of temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241606
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  • 3
    Electronic Resource
    Electronic Resource
    Rigid polyurethane foams: A model of the foaming process (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 840-844 
    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: A model of the manufacture of rigid polyurethane foams by free rising is presented. The extent of cream and rise periods as well as the amount of blowing agent necessary to give the desired foam density are theoretically predicted. The rate of blowing agent evaporation is calculated from an experimental boiling temperature vs. composition curve. Experimental runs were carried out with a formulation consisting of a polymeric isocyanate, a polyether polyol based on sorbitol, a silicone-polyol block-copolymer as surfactant, dibutyltin dilaurate as catalyst, and trichlorofluoromethane as blowing agent. Mixing was performed in situ in the mold using a commercial foaming machine. Experimental results gave a satisfactory agreement with model predictions. A diagram containing all the relevant information may be theoretically built and used for the selection of adequate operating parameters for a given formulation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221310
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  • 4
    Electronic Resource
    Electronic Resource
    Integral-skin polyurethane foams (1986)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 717-724 
    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: A model describing the expansion of a polyurethane (PU) foam in a closed mold is developed. An energy balance is stated, together with constitutive equations for the vaporization rate of the foaming agent and the polymerization kinetics. A numerical solution is obtained for an experimentally-characterized PU formulation. It is shown that in order to avoid premature gelling or undesirable density distributions, the wall temperature must be close to the initial one. The relative fraction of skin in the foam may be increased by decreasing the part thickness or by adding less catalyst or more blowing agent to the formulation. Factors affecting cream, rise, and process times are discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760261102
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  • 5
    Electronic Resource
    Electronic Resource
    Cure of epoxy resins containing epoxidized polyols (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 836-840 
    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: A commercial epoxy resin, consisting of a mixture of diepoxides based on diglycidyl ether of bisphenol-A (DGEBA) and containing an epoxidized polypropylene glycol as reactive diluent, was characterized by 1HNMR, FTIR, SEC, and chemical analysis. The kinetics of the cure with ethylenediamine (EDA) was catalyzed by the (OH) groups present in a large amount in the commercial formulation. A second order kinetic behavior gave an accurate fitting of results obtained by different experimental techniques (DSC in dynamic and isothermal modes and SEC in the pregel stage). The activation energy was E = 59.1 kJ/mol (14.1 kcal/mol), in very close agreement with values reported for the catalytic mechanism of the DGEBA-EDA polymerization. From the gel conversion and the critical stoichiometric ratio for samples containing an epoxy excess it was found that the average functionality of epoxidized species was f = 1.58.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760321211
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal conductivity of plastic foams (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 293-298 
    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: A simple equation enabling the prediction of the thermal conductivity of plastic foams, without the aid of adjustable parameters, is proposed. The equation is based on a recurrent method, previously developed, that showed reasonable agreement with experimental results. Ways of decreasing the thermal radiation contribution are shown. In particular, the influence of cell size, radiation transmission through solid membranes, and low-emissivity boundary surfaces are analyzed. Errors involved in steady techniques of measuring the thermal conductivity associated with radiation are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760230602
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  • 7
    Electronic Resource
    Electronic Resource
    Criteria for selecting cure cycles in autoclave processing of graphite/epoxy composites (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1140-1145 
    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: Room temperature mechanical properties, such as flexural strength and impact resistance, of epoxies and graphite/epoxy composites go through a maximum as a function of epoxy conversion. For tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM)-4,4′-diamlnodiphenylsulfone (DDS) formulations, the recommended cure cycle prescribes a maximum temperature close to 177°C. The maximum extent of reaction that may be obtained at this temperature is determined from the vitrification curve. At this maximum conversion, balanced mechanical and physical properties are attained in the partially cured specimen. However, if the standard cycle is used to cure thick parts, the maximum temperature inside the sample increases beyond 177°C. This leads to a complete conversion in most of the part and a consequent impairment of resulting physical and mechanical properties. It is shown how numerical solutions of differential energy and mass balances may be used to propose alternative cure cycles such that the maximum conversion at every point remains bounded by the vitrification curve. An illustration for a particular thickness is provided.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301805
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