Cannon Instrument miniPV Addendum - Manual (Page 4)

Defining and using a solvent blank for RV analysis
Using a solvent blank Relative viscosity by definition is a ratio between the
absolute viscosity* of a solution containing a solvent and sample material,
and the absolute viscosity* of the pure solvent . VISCPRO calculates this
ratio by comparing sample drop times for the solution and the solvent “blank”.
The significance of the resultant value is enhanced as two additional
variables are taken into account—sample/solvent density and (with drop
times under 200 seconds) an empirically-determined kinetic energy correction
constant.
*The term absolute viscosity, as used in this manual, is also known as
dynamic viscosity. For the purpose of VISCPRO
® software viscosity
calculations, and per ASTM D 2857 specifications, the absolute viscosity
is defined by the equation
η = Ctρ - Eρ/t 2 where C is a constant, t is the
drop time, ρ is the solution or solvent density and E is the kinetic energy
correction constant.
Relative viscosity calculation
The relative viscosity (RV) ratio (solute to solvent blank) is therefore defined
by the equation:
Software selection of blank
Since determination of a relative viscosity involves a comparison of solution
and blank, the VISCPRO controlling software requires the identification of a
blank for any samples tested using the Determine Solution Relative Viscosity
sample action. The blank is ordinarily selected from a list of solvents
maintained by the VISCPRO database. This list is accessible from the
Polymer Measurement Sample Options window by using the drop-down list
feature:
To display the list, click on the arrow. If the correct blank has not yet been
defined, the user may create a new blank by typing an ID for the blank into
the open field in the Polymer Measurement Sample Options window:
Procedure for blank definition
New blanks are created by testing the solvent in the miniPV using the
Determine Solvent Viscosity sample action. Follow the procedure fo
testing samples
1. Select Determine Solvent Viscosity as the sample action for the
desired sample.
2. Enter an ID for each blank that includes both a description of the
blank and also the temperature at which that blank is to be tested in
the miniPV. The blank must be tested at the same temperature
intended for the solution
NOTES
In some MiniPV applications involving dilute solutions, it may not be
necessary to input the density for the solvent blank and/or solution. If you
choose not to input solvent density for either the blank or for the sample,