摘要:

Liquid crystalline solutions ofcis‐poly(p‐phenylenebenzobisoxazole) in polyphosphoric acid (PBO/PPA) exhibit linear viscoelastic response to strains of 5% and satisfy time‐temperature superposition. The rheological behavior is suggestive of a weak gel‐like structure with a small breaking strain at low frequencies. The solutions are highly shear thinning over the entire range studied.

ISSN:0148-6055    

DOI:10.1122/1.550346

出版商:The Society of Rheology    

年代:1992

数据来源: AIP

摘要:

Slurries used in powder injection molding are typically made from high density fillers suspended in a molten wax or other carriers. Particle size and density and base fluid viscosity are the main experimental variables in this work. Slip corrections were made on all of the data for slurries of greater than 20 vol % solids content. Tests are reported on particles that cover a fivefold particle radius range. The data reflect a 1/rdependence on the particle radius. Particle densities range from 2.7 to 19.3 g/cm3. The data show a strong dependence on density. Base fluid viscosities range from 20 to 250 P, and it is shown that higher base‐fluid viscosities result in lower particle concentration effects on the relative fluid viscosity of the slurry. Rheological data are shown to be a function of the mean interparticle spacing, and plots of the relative viscosity versus the mean interparticle spacing exhibit an interesting convergence at about 150 μ.

ISSN:0148-6055    

DOI:10.1122/1.550348

出版商:The Society of Rheology    

年代:1992

数据来源: AIP

摘要:

Entry and exit flows through extrusion dies are studied numerical by for Bingham fluids exhibiting a yield stress. A constitutive equation proposed by Papanastasiou is used, which applies everywhere in the flow field in both yielded and practically unyielded regions. The emphasis is on determining the extent and shape of unyielded/yielded regions along with the extrudate swell (contraction) for planar and axisymmetric dies. The results for pressure are used to determine the excess pressure losses that give rise to entrance, exit, and the total end (or Bagley) correction.

ISSN:0148-6055    

DOI:10.1122/1.550350

出版商:The Society of Rheology    

年代:1992

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.550351

出版商:The Society of Rheology    

年代:1992

数据来源: AIP