Rheologica Acta

, Volume 10, Issue 3, pp 429–433 | Cite as

Extrapolation procedures for zero shear viscosity with a falling sphere viscometer

  • V. Subbaraman
  • R. A. Mashelkar
  • J. Ulbrecht
Article

Summary

Several theoretical and empirical extrapolation procedures for the determination of zero shear viscosity in a falling sphere viscometer are critically analysed. They are experimentally tested and it is concluded that the extrapolation procedure based onCaswells work appears to be the most appropriate.

Keywords

Polymer Viscosity Shear Viscosity Extrapolation Procedure Sphere Viscometer 

Notation

D

sphere diameter, cm

dc

container diameter, cm

F

1/6πD3(ϱ s −ϱ)g=drag force on sphere, dynes

FS

6πη0R v = drag force fromStokes law, dynes

fW

wall correction factor forNewtonian flow past a sphere

fB

bottom correction factor forNewtonian flow past a sphere

fI

inertial correction factor forNewtonian flow past a sphere

g

gravitational acceleration, cm/sec2

Re

2Rvt ϱ/η0 =Reynolds number

vt

measured sphere velocity, cm/sec

v

sphere velocity in an infinite medium, cm/sec

W

correction factor byCaswell [eq. 4]

Greek letters

η0

zero shear viscosity, poise

η0(N)

corrected viscosity [Eqn. 2], poise

ηs

apparentStokes viscosity, poise

ϱ

fluid density, gm/cm3

ϱs

sphere density, gm/cm3

τm(N)

maximum pseudo-Newtonian shear stress [eq. 2], dyne/cm2

λi

combination of material parameters

(i=1, 2, 3)

[eq. 4, 5, 6]

Zusammenfassung

Es werden einige theoretische und empirische Extrapolationsmethoden zur Bestimmung der Anfangs-Scherviskosität in einem Kugelfallviskosimeter kritisch analysiert. Diese werden experimentell überprüft, und es wird hieraus geschlossen, daß die Extrapolationsmethode, die auf der Arbeit vonCaswell beruht, die geeignetste zu sein scheint.

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Copyright information

© Dr. Dietrich Steinkopff Verlag 1971

Authors and Affiliations

  • V. Subbaraman
    • 1
  • R. A. Mashelkar
    • 1
  • J. Ulbrecht
    • 1
  1. 1.Department of Chemical EngineeringUniversity of SalfordSalford 5England

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