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  • Chemical Engineering  (21)
  • Wiley-Blackwell  (21)
  • Nature Publishing Group
  • 1
    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 interfacial strength of two paper-polypropylene-paper laminates used for electrical power transmission cable insulation has been measured using a peel test after a variety of conditionings that simulate the service thermal stress conditions. Immersion in dielectric oil at 23°C causes little decrease in peel strength, but heating in the oil at 90°C causes a rapid initial loss followed by a slow loss of strength. Cyclic and static heating show that cyclic fatigue is not a factor as the initial loss of strength occurs in a time comparable to the first two test cycles and further heating causes much less loss of strength. Tensile and compressive stresses resulting from cable winding have no effect on the loss of bond strength during heating in oil. Vacuum drying of the laminate and oil (as in cable manufacture) before heating results in less decrease in peel strength than heating without prior drying. Optical and electron microscopy show minimal wetting of the paper fibrils by the polypropylene with only a few having been either normal to or at a steep angle to the polypropylene surface. That is, the fibrils appear to be parallel to the interface and only partially immersed in the polypropylene. Micrographs show little, if any, differences between the interfaces on the two sides as well as little paper on the polypropylene after delamination and vice versa. It is suggested that the bonding mechanism is a combination of weak mechanical interlocking and secondary bonds. It is also suggested that swelling of the polypropylene relative to the paper by the dielectric oil at 90°C weakens the interfacial bond.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 1097-1106 
    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 sorption of toluene, dilute in CO2, and likewise the distribution coefficient of toluene between silicone rubber and CO2 have been explored from gaseous to supercritical fluid conditions. Sorption and desorption isotherms were determined by frontal analysis using a new inverse supercritical fluid chromatography technique at 35 and 70°C up to 250 bar. Complementary swelling data are presented for pure CO2 in silicone rubber up to 315 bar. A new result is that the sorption of toluene goes through a maximum and is highly adjustable over a continuum in the highly compressible region of carbon dioxide. This behavior is explained physically and predicted quantitatively with the Flory equation and the Peng-Robinson equation of state using only information from binary systems. These results are useful for a wide variety of applications including impregnation of polymers with pharmaceuticals, fragrances and other additives, and polymer purification.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 607-616 
    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 distribution coefficients of the solutes (toluene, naphthalene, and phenanthrene) are reported at infinite dilution between silicone rubber and supercriticalfluid carbon dioxide. A new technique is described in which a thin film of polymer is coated and cross-linked onto silica, and the distribution coefficient is measured rapidly by elution supercritical-fluid chromatography. Because CO2 significantly enhances the solute's volatility and its diffusion coefficient in the polymer, it is possible to study solute-polymer interactions at room temperature for nonvolatile compounds which would be difficult to study by conventional techniques such as gas chromatography. These infinite dilution data are used to determine solutepolymer interaction parameters to calculate phase diagrams over a wide concentration range. The residual, combinatorial, and cross-link contributions to the solute activity coefficient in the polymer are discussed as a function of concentration. In addition, pronounced pressure and temperature effects are described in terms of experimentally measured solute partial molar volumes (to - 14 L/mol) and partial molar enthalpies (to - 850 kJ/mol) in the fluid phase.
    Additional Material: 10 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1243-1253 
    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 degree of hydrogen bonding and macroscopic thermodynamic properties for pure and mixed fluids are predicted with the hydrogen bonding lattice fluid (LFHB) equation of state over a wide range in density encompassing the gas, liquid and supercritical states. The model is successful for molecules forming complex self-associated networks, in this case pure methanol, ethanol, and water, and the mixture 1-hexanol-SF6. In supercritical water, significant hydrogen bonding is still present despite all the thermal energy and is highly pressure- and temperature-dependent. A fundamental description of pressure and temperature effects on hydrogen bonding is presented for a well-defined case, the formation of a complex between a donor and acceptor in an inert solvent, where no self-association is present. The partial molar enthalpy and volume change on complexation both become pronounced near the critical point, where the density is highly variable with temperature and pressure.
    Additional Material: 14 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 37 (1991), S. 1441-1449 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An expanded liquid molecular thermodynamic model is developed to predict the solubilities of pure solids in a liquid expanded with a gaseous antisolvent. Experimental data are presented for systems containing naphthalene, phenanthrene, and a mixture of both in toluene expanded with a gas antisolvent, CO2. The pressure range is 1 to 64 bar and the temperature is 25°C. The data are predicted accurately with regular solution theory up to moderate pressures, but not at the higher pressures where the liquid phase is nearly pure CO2. In contrast, the new expanded liquid equation of state model describes the wide range of behavior from the nearly ideal liquid solution at ambient pressure to the highly nonideal compressible fluid at elevated pressures. As a result, it predicts solubilities accurately over three orders of magnitude by using only binary interaction parameters. The implications of the phase behavior on fractional crystallization with a gas antisolvent are discussed.
    Additional Material: 8 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 127-139 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Polymer microspheres and fibers are formed with a versatile new process, precipitation with a compressed fluid antisolvent. By spraying a 1 wt. % polystyrene in toluene solution into CO2 through a 100-μm nozzle, microspheres are formed with diameters from 0.1 to 20 μm as the CO2 density decreases from 0.86 to 0.13 g/cm3. The uniform submicron spheres produced at high CO2 density are due in part to the rapid atomization produced by the large intertial and low interfacial forces. Fibers, with and without microporosity, are obtained at higher polymer concentrations where viscous forces stabilize the jet. The effect of CO2 density and temperature on the size, morphology and porosity of the resulting polymeric materials is explained in terms of the phase behavior, spray characteristics, and the depression in the glass transition temperature.
    Additional Material: 10 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1363-1369 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A systematic formulation of multicomponent/multiphase phase equilibria as a linear algebra problem in the fugacities, mole fractions, partial molar volumes, and partial molar enthalpies is given. The algorithm takes advantage of the Gibbs-Duhem relationships for each phase and a modified Gaussian elimination technique to reduce the system of equations. These algorithmic steps allow current symbolic manipulation packages to generate useful partial derivative relationships in terms of measurable thermodynamic quantities. Features of the algorithm are demonstrated by applying a computer implementation of the method to a simple two-phase/two-component system and to the more complicated examples of a two-phase/three-component supercritical fluid chromatography experiment and a mass-conserving closed system.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1639-1649 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Elliptical basis function (EBF) networks are introduced as a new nonparametric method of estimating probability density functions for process data. Unlike Parzen window density estimators that use identical hyperspherical basis functions, the EBF method uses elliptical basis functions adapted to the local character of the data. This technique overcomes the spikiness problem associated with Parzen windows, where in high dimension, they can fail to produce smooth probability density estimates. The EBF estimator produces valid density functions that converage to the underlying distribution of the data in the limit of an infinite number of training examples. A technique based on statistical cross validation is introduced for evaluating different density estimators. The criterion is a measure of how well the density estimator estimates the density of data not used in the training. The EBF density estimation method and the evaluation technique are demonstrated using several examples of fault diagnosis.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 543-555 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phase behavior data and FTIR spectra along with solubilities and solvatochromic shifts of ionic indicator dyes are reported for binary, ternary and quaternary systems composed of pentaethylene glycol n-octyl ether (C8E5), CO2, water, and n-pentanol as a function of temperature, pressure and composition. With the addition of n-pentanol as a cosurfactant, the water to surfactant ratio, W0, reaches values as high as 12. As water is added further, a surfactant-rich phase precipitates due to micellemicelle interactions. Ionic dyes are soluble at levels of 0.03 mM, far in excess of the negligible solubility in pure CO2.
    Additional Material: 17 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 2415-2426 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A maximum likelihood rectification (MLR) technique that poses the data-rectification problem in a probabilistic framework and maximizes the probability of the estimated plant states given the measurements is proposed. This approach does not divide the sensors into “normal” and “gross error” classes, but uses all of the data in the rectification, each sensor being appropriately weighted according to the laws of probability. In this manner, the conventional assumption of no sensor bias is avoided, and both random errors (noise) and systematic errors (gross errors) are removed simultaneously. A novel technique is introduced that utilizes historical plant data to determine a peior probability distribution of the plant states. This type of historical plant information, which contains the physical relationships among the variables (mass balances, energy balances, thermodynamic constraints), as well as statistical correlations among the variables, has been ignored in prior data-rectification schemes. This approach can use the historical plant information to solve a new class of data-rectification problems in which there are no known model constraints. The MLR method is demonstrated on data from a simulated flow network and a simulated heat-exchanger network. The MLR technique provides considerably improved performance over existing data-reconciliation schemes in these examples.
    Additional Material: 9 Ill.
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