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  • 1
    Electronic Resource
    Electronic Resource
    Shear viscosity of slightly-elastic concentrated suspensions at low and high shear rates (1988)
    Springer
    Rheologica acta 27 (1988), S. 596-607 
    Details
    ISSN: 1435-1528
    Keywords: Effectiveviscosity ; concentratedsuspension ; sphericalparticle ; secondorderfluid ; Harnoyfluid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A quasi-static asymptotic analysis is employed to investigate the elastic effects of fluids on the shear viscosity of highly concentrated suspensions at low and high shear rates. First a brief discussion is presented on the difference between a quasi-static analysis and the periodic-dynamic approach. The critical point is based on the different order-of-contact time between particles. By considering the motions between a particle withN near contact point particles in a two-dimensional “cell” structure and incorporating the concept of shear-dependent maximum packing fraction reveals the structural evolution of the suspension under shear and a newly asymptotic framework is devised. In order to separate the influence of different elastic mechanisms, the second-order Rivlin-Ericksen fluid assumption for describing normal-stress coefficients at low shear rates and Harnoy's constitutive equation for accounting for the stress relaxation mechanism at high shear rates are employed. The derived formulation shows that the relative shear viscosity is characterized by a recoverable shear strain,S R at low shear rates if the second normal-stress difference can be neglected, and Deborah number,De, at high shear rates. The predicted values of the viscosities increase withS R , but decrease withDe. The role ofS R in the matrix is more pronounced than that ofDe. These tendencies are significant when the maximum packing fraction is considered to be shear-dependent. The results are consistent with that of Frankel and Acrivos in the case of a Newtonian suspension, except for when the different divergent threshhold is given as [1 − (Φ/Φ m )1/2] − 1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01337455
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of some structural features of the polymer support on synthesizing 2,4,6-tribromophenyl benzyl ether in a triphase catalysis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 34 (1994), S. 187-195 
    Details
    ISSN: 0959-8103
    Keywords: Triphase catalysis ; synthesis of 2,4,6-tribromophenyl benzyl ether ; structural features of polymer support ; 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 substitution reaction of benzyl bromide and 2,4,6-tribromophenol in an organic solvent/alkaline aqueous solution of KOH by triphase catalysis in which tributylamine was immobilized on a polymer support was investigated. Our main purpose was to evaluate the effect of some structural features of the polymer-supported pellet on the conversion of the organic-phase reactant (benzyl bromide). The polymer-supported pellet was obtained from copolymerization of styrene and chloromethylstyrene monomers. The reaction was identified as occurring both on the surface and within the particles of the polymer support when using a highly polar solvent. The effects of the structural features of the polymer support, which are related to the degree of cross-linking, ring substitution, lipophilicity of the polymer pellet, the chloride density and the solvents, on the conversion of benzyl bromide were investigated in detail. The experimental results indicate that 2% of cross-linking with 10% ring substitution of the macroporous polymer support provides a rapid reaction and high conversion of benzyl bromide reactant.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210340210
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