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  • 1
    Electronic Resource
    Electronic Resource
    On-line optimizing control of a packed-bed immobilized-cell reactor (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 626-632 
    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: On-line optimizing control has been used to find and track the economically optimal operating conditions of a packed-bed reactor. The continuous reactor under study converts the ammonium salt of fumaric acid to aspartic acid using whole cells immobilizing in K-carrageenan beads. The on-line optimizing control was performed using a leastsquares recursive estimation algorithm with a variable forgetting factor to estimate the parameters in a linear discrete-time model. A Newton optimization procedure used these parameters to calculate the direction and distance to the optimal conditions. Features found to enhance the speed and stability of the algorithm included the use of a variable forgetting factor algorithm, both low- and high-pass filtering of the data, outlier rejection, and linearizing input-outupt transformations.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690340412
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  • 2
    Electronic Resource
    Electronic Resource
    Electrochemical measurement of effective diffusivity in Hall-Heroult electrolyte (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 1649-1655 
    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: Forced-convection mass transfer at the metal/bath interface during aluminum reduction from cryolitic melts was studied under reproducible convective conditions. A film of molten aluminum on a rotating molybdenum cylinder was the cathode. Concentration overpotential measured as a function of rotation rate, current density, and bath composition was converted to concentration differences between the bulk and the metal surface. Chosen as the basis for calculation of a mass transfer coefficient was the concentration of aluminum fluoride given by: \documentclass{article}\pagestyle{empty}\begin{document}$$ C_{{\rm AlF}_{\rm 3} } = \frac{{2\rho (100 - Al_2 {\rm O}_3 \% - {\rm CaF}_2 \% - IMP\%)}}{{100M_{{\rm AlF}_3} (CR + 2)}} $$\end{document} where the amounts of indicated compounds are in weight percent, IMP designates impurities, M is molecular weight, ρ is the density of the melt, and CR is the cryolite ratio, the ratio of moles NaF to moles AlF3. Agreement with a correlation for mass transfer to a rotating cylinder allowed the calculation of effective diffusivities for aluminum fluoride species, in alumina-saturated melts, of: 11.1 ± 1.1 × 10-5 cm2/s at 1.8 CR; 11.4 ± 1.7 × 10-5 cm2/s at 2.3 CR; 5.4 ± 0.8 × 10-5 cm2/s at 3.0 CR; and 4.4 ± 0.9 × 10-5 cm2/s at 4.0 CR.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690341008
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  • 3
    Electronic Resource
    Electronic Resource
    Miniemulsion copolymerization of vinyl acetate and butyl acrylate. II. Mathematical model for the monomer transport (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 26 (1988), S. 1495-1517 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A mathematical model is presented to describe the monomer transport between monomer droplets, aqueous phase, and polymer particles during the course of an emulsion polymerization. The model was used to investigate the role of the cosurfactant (hexadecane) in the miniemulsion copolymerization of 50:50 molar ratio vinyl acetate-butyl acrylate monomer mixture, as well as the effect of the different components and process variables on the rate of copolymerization, monomer distribution between phases, and composition of the copolymer.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1988.090260712
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  • 4
    Electronic Resource
    Electronic Resource
    Fiber orientation and its effect upon thermoelastic properties of short carbon fiber reinforced poly(etheretherketone) (PEEK)This project was performed as partial fulfillment of a master's degree with funding provided by ICI, Ltd., and Rolls Royce, Ltd. (1987)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 8 (1987), S. 74-81 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Experimental and analytical techniques are employed in the present study to investigate the influence of microstructure on thermoelastic properties of short carbon fiber reinforced poly(etheretherketone). The test specimen geometry is an edge gated, injection molded dogbone tensile bar. Typical of injection molded structures, three distinct layers of fiber orientation were discernable through the sample thickness. The thermoelastic properties of the surface layer (machined from the specimen) are measured for direct correlation with a micromechanics model. In addition to measuring the volume fractions and constituent properties, microstructural features such as fiber aspect ratio and the process-induced fiber orientation distribution are quantified. Correlation of experimental data with micromechanics model predictions is found to be quite good.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750080203
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  • 5
    Electronic Resource
    Electronic Resource
    Process induces fiber orientation: Numerical simulation with experimental verification (1985)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 6 (1985), S. 82-86 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The performance of short fiber molded composite structures is determined uniquely by the properties of the molding material and the process induced fiber orientation. Consequently, the capability to accurately predict the fiber orientation distribution is of fundamental importance in computer-aided mold design. Methodology for the numerical prediction of fiber orientation during the mold-fill process is presented for a short glass fiber thermoset (57 percent phenolic resin, 10 percent calcium carbonate filler, and 33 percent glass fiber by volume). On the basis of a finite element flow characterization, Jeffery's orientation equation is numerically integrated along streamlines to calculate fiber orientation. Correlation of experimental and numerical results for an end-gated bar with a molded-in hole is reasonably good.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750060204
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of pH and temperature on cardioactive polypeptides from sea anemones: A 1H-nmr study (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 1143-1157 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of pH and temperature on the 300-MHz 1H-nmr spectra of three cardioactive polypeptides from sea anemones, anthopleurin-A from Anthopleura xanthogrammica (AP-A) and Anemonia sulcata toxins I and II (ATX I and II), are described. AP-A and ATX II exhibit major spectral heterogeneity. Evidence from the pH and temperature studies and from high performance liquid chromatography indicates that this heterogeneity is conformational rather than chemical in origin. By contrast, purified isotoxins of ATX I show no evidence of conformational heterogeneity. The pKa values of most of the ionizable groups in these polypeptides are not strongly perturbed by interactions in the tertiary structure, with the exception of one of the Asp carboxylates, which has a pKa of ≲ 2 in AP-A and ATX II and 3.0 in ATX I. Protonation of this carboxylate, suggested to be Asp-9, leads to a conformational change in all three molecules. All three polypeptides are thermally stable, showing some conformational changes but not major unfolding at elevated temperatures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270708
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  • 7
    Electronic Resource
    Electronic Resource
    Materials, research - current issues and future directions (1989)
    Weinheim : Wiley-Blackwell
    Advanced Materials 1 (1989), S. 140-141 
    Details
    ISSN: 0935-9648
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19890010502
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  • 8
    Electronic Resource
    Electronic Resource
    Wetting properties of homopolymers and copolymers of pentafluorostyrene and methylacrylate and homopolymer blends (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 657-667 
    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: Polypentafluorostyrene (PPFS), polymethylacrylate (PMA), and poly(pentafluorostyrene-co-methylacrylate), poly(PFS-co-MA) were prepared and the wetting characteristics of polymer blends of PPFS and PMA were compared with that of poly(PFS-co-MA) via contact angle measurements. The critical surface tension of polypentafluorostyrene was found to be 22.6 dyne/cm, which is comparable to the value reported for polytrifluoroethylene (22 dyne/cm). The critical surface tension of poly(PFS-co-MA) is not linearly related to its composition. The polymer blends of PPFS and PMA exhibit significant surface enrichment of the fluoropolymer. The harmonic-mean method1 was employed to determine surface tensions of these polymers and many known polymers. It is found that the method produces useful surface tension data provided the contact angle values are derived from testing liquids of dissimilar polarity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330227
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  • 9
    Electronic Resource
    Electronic Resource
    Optimization of polymer-solvent interaction in a multisolvent system by the UNIFAC group-contribution method (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 5007-5019 
    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 solubility parameter scheme is an exceptionally useful tool for predicting the solubility behavior of simple polymer systems. However, this scheme is unable to handle well enough complicated systems, such as those involving donor-acceptor interactions and those containing more than two solvents. More advanced thermodynamic treatments and computer techniques, such as UNIFAC, can be a key to solving these kinds of problems.The UNIFAC group-contribution method utilizes a volume parameter and a surface-area parameter for each structural group and a pair of interaction-energy parameters for each pair of groups, which can be deduced from experimental activity data. The method was originally derived for mixtures of ordinary liquids and has been extended to polymer solutions by adding a free-volume correction. The modified UNIFAC method can be used to estimate the activities of solvents in a polymer solution, even when no experimental data are available for the mixture.In the present study, the UNIFAC method was applied to optimize polymer-solvent interactions in three-solvent systems. A three-dimensional plot, displaying polymer activity as a function of the solvent composition, was constructed for each polymer system. The minimum in polymer activity was used as the criterion for maximum polymer-solvent interaction. Dissolution rate and solution clarity were used to test the polymer-solvent interaction experimentally. Comparison of theoretical predictions with experimental results indicated that a better agreement could be obtained by using the UNIFAC method rather than the solubility parameter method.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320522
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  • 10
    Electronic Resource
    Electronic Resource
    Dielectric studies of the cure of epoxy matrix systems (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 1155-1167 
    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: Dielectric spectroscopy was used to monitor the curing process of two epoxy resin systems. The basic system (system I) consisted of DGEBA (a difunctional epoxy) and a polyamide in a 50-phr mixture. In addition, a comparative analysis was performed on a high-performance resin system (system II) used primarily in unidirectional composite applications. This system contained TGDDM (a tetrafunctional epoxy) and DDS (a tetrafunctional amine) in a 25-phr mixture. The dielectric data were obtained using a simple yet functional sample cell electrode designed and constructed in the laboratory. For system I, isothermal dielectric data were used to determine apparent activation energies for the temperature range from 22 to 70°C. The data showed that the activation energy was a function of temperature and increased as the temperature of the cure increased. This indicated that the reaction mechanism was also a function of temperature. For system II, data were collected between 140 and 190°C and an overall activation energy for that temperature range was determined. The overall activation energies for both systems, calculated using dielectric spectroscopy, compared favorably to those obtained using differential scanning calorimetry. Also, using a wider frequency range (240 Hz to 2 MHz), Argand diagrams were constructed and modeled with the Cole-Cole empirical equation for systems with a distribution of relaxation times. This justified the calculation of average relaxation times, which could then be related to the bulk physical properties of the polymer, such as viscosity. Modified Argand diagrams, where ε″ is plotted against ε′ at one frequency as a function of time, were also constructed, which aided in the understanding of the curing processes for these thermosetting systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070310501
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