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  • Chemical Engineering  (91)
  • GENERAL
  • 1985-1989  (93)
  • 1955-1959
  • 1989  (93)
  • 1
    Electronic Resource
    Electronic Resource
    Optical fiber chemical sensors utilizing dye-doped silicone polymer claddings (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 1215-1218 
    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: Transparent dimethyl siloxane network polymers with refractive indices near 1.40 may be applied to fused silica fibers (n = 1.458) as they are drawn to produce plastic-clad silica (PCS) optical fibers. The evanescent tail of the light energy propagating in the core of such fibers extends into the silicone cladding, where it interacts with chemical species present in the polymer. If the silicone is doped with a dye, the absorption spectrum or fluorescence spectrum of the dye is reflected in the transmission spectrum of the fiber. Further, if the dye changes its absorption spectrum or fluorescence spectrum as a result of diffusion of a chemical species into the silicone, the change is detectable in the fiber output. The polymer material properties which determine the performance of these sensors are described, along with examples of sensors for ammonia and oxygen which utilize either color changing or fluorescent dyes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760291715
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  • 2
    Electronic Resource
    Electronic Resource
    Fluid mixing with a pipeline tee: Theory and experiment (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 406-414 
    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 pipeline mixing of two fluid streams by turbulent jet injection normal to the pipeline has been studied theoretically and experimentally. A simple scaling law for the second moment of the tracer concentration within the pipeline is proposed for the first fifteen pipe diameters down-stream from the injection point. The similarity solution is derived by assuming that the tracer diffuses in a weak compound jet moving parallel to the pipeline axis. The theoretical results are correlated with all of the available experimental measurements. The results indicate that the second moment of the tracer concentration decreases with increasing jet momentum and distance from the injection point such that M = 0.25. (lm/D)-2 (x/D)-4/3.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350308
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  • 3
    Electronic Resource
    Electronic Resource
    Laser capillary spectrophotometry for drop-size concentration measurements (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 1073-1084 
    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: A laser capillary spectrophotometric technique (LCS), based on the method of Verhoff et al. (1969, 1977), is developed for the rapid and accurate determination of the bivariate drop size-concentration distribution for reactive liquid-liquid dispersions. The method employs a precision bore capillary, through which a sample is drawn from the mixing vessel by a vacuum pump. An appropriate light source is used to distinguish between the slugs of dispersed phase and continuous phase as the sample passes by two detection points in the capillary. The optical device is designed to measure drop size by the difference of light refraction between the two phases and drop concentration by the light absorbance of the organic phase in the drop. The new technique can automatically measure drop-size and drop-concentration distributions of thousands of drops within a few minutes. This technique can provide important information on the state of a reactive dispersion in situ and can provide information on the influence of dispersed-phase mixing effects on mass transfer and/or reactions in liquid-liquid dispersions. Further, the LCS technique provides the capability for on-line monitoring and control of units processing liquid dispersions.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350703
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  • 4
    Electronic Resource
    Electronic Resource
    Laser photometric probe for concentration measurements in liquid dispersions (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 507-510 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350319
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  • 5
    Electronic Resource
    Electronic Resource
    4,4′-Isophthaloyidiphthalic anhydride polyimidesPresented in priliminary from at the ACS Toronto, Canada Meeting: Polymer Preprints, 29(1), 128 (1988). (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 63-68 
    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 series of polyimides based on 4.,4′-isophthaloyldiphthalic anhydride (IDPA) was prepared and characterized by inherent viscosity, differential scanning calorimetry (DSC), solubility, wide-angle X-ray scattering (WAXS), and isothermal thermogravimetric analysis (ITGA). Film forming, tough, insoluble polyimides were obtained with most of the 11 diamines used for evaluation. Two materials were semicrystalline. Several compositions showed excellent thermooxidative stability by ITGA at 300 and 350°C in air, as compared to Kapton-H (Du Pont) film. The IDPA-m-phenylenediamine (m-PDA) composition, for example, gave a flexible, amorphous film having a Tg of 259°C (identical with LARC-TPI) and insoluble in a wide range of solvents. It is based on a potentially low-cost dianhydride (IDPA) and, unlike LARC-TPI, a low-cost, domestically available diamine which gives a negative Ames test.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760290111
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  • 6
    Electronic Resource
    Electronic Resource
    “A semi-empirical algorithm for flow balancing in multi-cavity transfer molding” (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 1796-1796 
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760292409
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  • 7
    Electronic Resource
    Electronic Resource
    A semi-empirical algorithm for flow balancing in multi-cavity transfer molding (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 749-761 
    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: Multi-cavity transfer molding is an important process step in several electronic and photonic technologies. In some applications, uniform filling of the cavities of the mold, or mold balancing, is required. A semi-empirical flow model to predict mold filling patterns was developed. The algorithm is a one-dimensional network flow simulation that uses experimental pressure drop data to determine the volumetric flow rate through the gates and runners. A comprehensive experimental program was undertaken to determine these hydraulic resistances for different flow rates and mold geometries. A theoretical treatment is also described to compute hydraulic resistance from gate geometry. Uniform gate resistances provide unbalanced filling and higher velocities in the cavities. Balanced filling can significantly reduce the molding compound velocity and the flow induced stresses, but imperfect balancing compromises the benefits. Experimental filling patterns were obtained for two sets of gates. The agreement between the model and the experiments was satisfactory, and the discrepancies were attributed to correctable phenomena.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760291108
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  • 8
    Electronic Resource
    Electronic Resource
    Liquid flow in molds with prelocated fiber mats (1989)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 10 (1989), S. 414-423 
    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 mechanism associated with mold filling in the manufacture of structural RIM (SRIM) and resin transfer molding (RTM) composites is studied by means of flow visualization and pressure drop measurements. To facilitate this study, an acrylic mold with a variable cavity was constructed and the flow patterns of nonreactive fluid flowing through various layers, types, and combinations of preplaced glass fiber reinforcement mats were photographed for both evacuated and nonevacuated molds. The pressure drops in the flow through a single type of reinforcement (e.g., a continuous strand random fiber mat) and also a combination of reinforcement types (e.g., a stitched bidirectional mat in combination with a random fiber mat) were recorded at various flow rates to simulate high-speed feeding processes (e.g., SRIM) and low-speed feeding processes (e.g., RTM). By changing the amount of reinforcement placed into the mold, the permeabilities of the different types and combinations of glass fiber mats were obtained as a function of porosity. It is shown that partially evacuating the mold cavity decreases the size of bubbles or voids in the liquid, but ultimately increases the maximum pressure during filling. The results also show that glass fiber mats exhibit anisotropic permeabilities with the thickness permeability, Kz, being extremely important and often the determining factor in the pressure generated in the mold during filling.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750100605
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  • 9
    Electronic Resource
    Electronic Resource
    A comparison of oven sag temperature and heat deflection temperature for measuring heat resistance (1989)
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 11 (1989), S. 184-189 
    Details
    ISSN: 0193-7197
    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 , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The plastics industry places great emphasis on heat deflection temperature (HDT) as a measure of heat resistance when designing a plastic product. However, many manufacturers will evaluate a material's heat resistance by exposing a finished part to meximum use temperature under gravity load rather than the high loadings associated with the heat deflection test. The oven sag test is an alternate method which looks at the sag of a molded bar under gravity load. One end of the bar is clamped while the other end is free to sag. By employing a range of temperatures, the temperature at which gross sag takes place can be found. This study investigated how well the heat deflection temperature test and the oven sag test correlate to the performance of an injection molded box subjected to high temperatures using one and two phase PVC blends. The oven sag test was found to provide a more practical and more accurate measure of a material's performance under high temperatures and no external load. It is particularly well suited for evaluating two phase polymer blends.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/vnl.730110409
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamics and control of quasirational systems (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 1017-1028 
    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: Systems having transfer functions of the form \documentclass{article}\pagestyle{empty}\begin{document}$$ G_P (s) = \frac{{P_1 (s) - P_2 (s)e^{ - t_d s} }}{{Q(s)}}, $$\end{document} where P1(s), P2(s) and Q(s) are polynomials, are called quasirational distributed systems (QRDS). They are encountered in processes modeled by hyperbolic partial differential equations. QRDS can have an infinity of right half-plane zeros which causes large phase lags and can result in poor performance of the closed-loop system with PID controllers. Theory on the asymptotic location of zeros of quasipolynomials is used to predict the nonminimum phase characteristics of QRDS and formulas are presented for factoring QRDS models into minimum and non-minimum phase elements.A generalized Smith predictor controller design procedure for QRDS, based on this factorization, is derived. It uses pole placement to obtain a controller parameterization that introduces free poles which are selected to satisfy robustness specifications. The use of pole placement allows for the design of robust control systems in a transparent manner. Controller selection is generally better, simpler and more direct with this procedure than searching for optimal PID controller settings.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350615
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