摘要:

The double model concept of Wang and Zimm combined with Roscoe's self‐consistency approach has been used to obtain the concentration dependence of the viscosity and normal stress coefficients for a solution of linear flexible macromolecules in the limit of zero rate of shear. The expressions are simple in form and qualitatively correct as long as one stays well below the critical concentration.

ISSN:0148-6055    

DOI:10.1122/1.549607

出版商:The Society of Rheology    

年代:1980

数据来源: AIP

摘要:

An axial annular‐flow instrument was used to determine the secondary normal stress difference,N2=σrr−σφφ,in case the velocity field is expressed asvr=0,vφ=0,andvz=vz(r).The pressure difference, at a fixed axial position, between inner and outer walls of the annulus was measured at various shear rates or axial pressure gradients. The pressure at the outer wall is found to be higher than that at the inner wall throughout the experiment. This meansN2is tensile. The data of pressure difference were analyzed to obtainN2as a function of shear stress.N2increases with the square of shear stress at a low shear stress but at a rate slightly less than that when shear stress is above 0.08 MPa or so. Also,N2is compared with the primary normal stress difference,N1,which had been determined from the measurement of exit pressure with a capillary‐type instrument. The magnitude ofN2relative toN1is found to be 20–40% for the polymer melts we used.

ISSN:0148-6055    

DOI:10.1122/1.549593

出版商:The Society of Rheology    

年代:1980

数据来源: AIP

摘要:

Experimental and theoretical work defining the effects of Brownian motion and dispersion, steric, and electrostatic forces on the rheology of suspensions is reviewed. Data from well‐characterized monodisperse systems are interpreted through analyses, primarily of pair interactions, which relate the bulk stress to the suspension microstructure. The magnitudes of the interparticle forces relative to Brownian motion determine the nature of the microstructure at rest: neutrally stable, stable due to strong electrostatic or steric repulsions, or flocculated by strong attractive forces. The rheological behavior varies correspondingly from moderately shear thinning with Newtonian low‐ and high‐shear viscosities for hard sphere interactions to solidlike in the low‐shear limit when multiparticle attractive or repulsive forces dominate Brownian motion.

ISSN:0148-6055    

DOI:10.1122/1.549564

出版商:The Society of Rheology    

年代:1980

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549594

出版商:The Society of Rheology    

年代:1980

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549588

出版商:The Society of Rheology    

年代:1980

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549604

出版商:The Society of Rheology    

年代:1980

数据来源: AIP