TA Instruments AR 2000, Operator'S Manual

Page: 119 / 144

AR 2000 Operator's Manual
119
Interfacial Shear Stress and Shear Rate Calculation
To calculate the interfacial viscosity, a two-dimensional analog of the concentric cylinder geometry is used. The
interfacial shear stress, shear rate and viscosity, are then calculated as:
where R
D
is the disc radius and R
C
the cup inner radius. For the dimensions given above:
σ
interfacial
= 118.57 x M
interfacial
;
interfacial
= 6.207 x
Ω
and
η
interfacial
= 19.103 x M
interfacial
/
Ω
where the units of torque are in Nm, and the units of angular velocity are in rad s
-1
.
Note: the units of interfacial shear stress in the S.I. system are N m
-1
, the units of interfacial shear rate are s
-1
and the units of interfacial viscosity are Pa.s.m (pascal second metres).
Part Numbers
For re-ordering, the following part numbers should be used.
Item Part Number
Interfacial Assembly (complete system) 545901.901
Interfacial Cup 545922.001
Interfacial Geometry 545931.001
References
[1] D.A. Edwards, H. Brenner and D.T. Wasan "Interfacial Transport Processes and Rheology" Butterworth-
Heinemann, Boston (1991).
[2] S-G. Oh and J.C. Slattery, Journal of Colloid and Interface Science, 67, 516 - 525 (1978).
[3] E. Shotton, K. Wibberley, B. Warburton, S.S. Davis and P.L. Finlay, Rheologica Acta, 10, 142-152 (1971).