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  • Polymer and Materials Science  (14)
  • Biochemistry and Biotechnology  (2)
  • Cytochrome P450  (2)
  • 11
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 817-825 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The extended Taylor dispersion method was used to determine the translational diffusion coefficients of a series of polystyrene standards in 1,4-dioxane at infinite dilution at temperatures from 323.2 to 378.2 K. The experimental data suggest that in the context of Kirkwood's theory the Monte Carlo chain represents real polystyrene molecules better than does the Guassian chain with physically reasonable values for the hydrodynamic interaction parameter h*. The feasibility and accuracy of the simultaneous determination of the diffusivities of several polystyrene standards from a single dispersion measurement were also analyzed using a binary mixture of polystyrenes with molecular weights of 2000 and 100,000 as an example.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 1473-1480 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The translational diffusion coefficients for three relatively short, nearly monodisperse polystyrene chains (with molecular weights 2000, 4000, and 9000) in liquid cyclohexane have been measured up to 523.2 K using the extended Taylor dispersion method. The resultant hydrodynamic radii are successfully interpreted with the freely jointed chain model corrected for the approximations intrinsic to Kirkwood's theory with Stokes' radius as the only adjustable parameter, which is found to decrease with chain length but approach a constant value for long enough chains. The experimentally observed hydrodynamic radii of polystyrene standards with molecular weights 17,500, 50,000 and 100,000 at 308.2 K conform quite well to the values predicted with the approach formulated in this work.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 1791-1798 
    ISSN: 0887-6266
    Keywords: alternating poly(ethylene-propylene) (hydrogenated polyisoprene) melts ; pressure-volume-temperature (P-V-T) properties ; density ; specific volume ; equations of state ; Flory-Orwoll-Vrij (FOV) ; Modified Cell Model (MCM) ; Sanchez-Lacombe (SL) ; Statistical Associating Fluid Theory (SAFT) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pressure-volume-temperature (P-V-T) properties of monodisperse alternating poly(ethylene-propylene) (hydrogenated polyisoprene) melts of varying molecular weights are measured at 0.1 MPa 〈 P 〈 200.1 MPa, and 290 K 〈 T 〈 510 K in a dilatometer-type apparatus. The Flory-Orwoll-Vrij (FOV), Modified Cell Model (MCM), Sanchez-Lacombe (SL), and the Statistical Associating Fluid Theory (SAFT) equations of state are found to correlate the experimental data with excellent accuracy, except either at low pressures and high temperatures, or at high pressures and low temperatures. On average, MCM and SAFT fit the data slightly better than FOV and SL. The equation-of-state parameters are found to be independent of molecular weight, especially for SAFT, as required by the theory. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 793-799 
    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: Characteristics of gas penetration and polymer melt flow in gas-assisted injection molded spiral tubes was investigated by simulations and experiments. Distribution of the skin melt thickness along the gas flow direction was measured, and gas penetration in the primary and secondary stages was identified. An algorithm based on the control-volume/tiniteelement method combined with a particle-tracing scheme using a dual-filling-parameter technique is utilized to predict the advancements of both melt front and gas from during the molding process. The simulated distribution of gas penetration shows reasonably good coincidence with experimental observations. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 2075-2094 
    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 diffusion coefficient (D) and the solubility coefficient (K) of three sulfonated azo dyes were measured in swollen gelatin membranes at pH 12 by two techniques (time lag and desorption rate), with good agreement between the two. A strong correlation was established between log D and the reciprocal of the free volume of the matrix. Hence, as free volume of the matrix increased (due to increasing solvent imbibition), dye mobility increased. As dye size increased, however, mobility decreased. Dye affinity for gelatin, as measured in dilute solutions by dynamic dialysis, was small and could be related to the dye solubility in more concentrated gelatin matrices. Increasing ionic strength or decreasing alcohol content increased K without affecting the dye mobility. On the other hand, the presence of polymers with strong affinity for the dye anions, e.g., polyvinylpyrrolidone, immobilized a large fraction of the dye ions and greatly slowed the overall dye transport.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 2831-2843 
    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: An experimental study was carried out to investigate the effect of mixing on the state of dispersion and rheological properties in the two-phase flow of polymer blends. For the study, blends of polystyrene and polypropylene were used, and two mixing devices were employed: a single-screw extruder combined with a “static mixer,” and a twin-screw compounding machine. Materials of various blending ratios were extruded at a constant temperature (200°C) through a capillary die having an L/D ratio of 20 (D = 0.125 in.). The state of dispersion in the two-phase system was investigated from pictures taken of the microstructure of the extrudate samples. It was found that different mixing devices have a profound influence on the state of dispersion of one polymer in another. Also determined were the rheological properties of the two-phase system investigated, from wall normal stress measurements. Our results show that, when shear stress is used as a parameter, the melt viscosity goes through a minimum, whereas the melt elasticity goes through a maximum. This is regardless of the type of mixing device employed, although the shapes of the curves are affected by the type employed. It is suggested that shear stress, instead of shear rate, be used in correlating the viscoelastic properties of two-phase polymer systems.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2457-2468 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The translational diffusion coefficients are reported for polystyrenes with molecular weights 2000, 4000, and 9000 in cyclohexane at infinite dilution from 283.2 to 348.2 K. The results suggest that the hydrodynamic radii stay constant to within ±3% and that the real chain for molecular weight 9000 at 308.2 K is well represented by a Gaussian or Monte Carlo model involving the idea of statistical steps. Furthermore, the success of Hildebrand's free-volume empiricism has led to a correlation between Dμ0/T and M which represents the observed diffusivities to within ±2%.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Advances in Polymer Technology 12 (1993), S. 361-378 
    ISSN: 0730-6679
    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
    Notes: The Intelligent Processing of Materials (IMP) concept has been applied to the calendering process with the goal of improving shape quality and process efficiency. All four basic features of the IPM, including modeling, data processing, sensing, and controlling, are considered. In the process modeling, bending and thermal models are developed. With these models, the relationship between the process parameters and quality of the calendered sheets has been established. A material data bank has been established to couple with the process modeling and real-time sensing data. In sensing, ultrasonic and temperature sensors have been implemented to measure critical quality and process parameters in situ. The sensing data have been used not only to verify the modeling prediction but also to establish information needed to diagnose the causes of the layflat problem. Based on the model prediction as well as sensing information, a better control system to alleviate layflatness problems has been developed. Finally, a control strategy for future improvement of the calendering system is proposed. © 1993 by John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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