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VISCOSITY SOLIDS RELATIONSHIP OF A POLYMER
SOLUTION USING TWO DATA POINTS
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WLF equation
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This program assumes that the glass transition temperature (Tg)of a polymer
decreases linearly with the weight fraction of solvent. Using the WLF
equation (William, Landel and Ferry Equation) the viscosity of
the polymer solution can be calculated from the Tg. Universal
constants according to Nielsen are used for
this calculation. This program also assumes that no unusual
interaction polymer-solvent is taking place. The largest error
introduced into this calculation comes from the solids
determination.
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Tgs = Co +C1Ws
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Tgs = solution Tg
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Co, C1= constants
for polymer solution
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Ws = weight fraction of
solvent
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The constants Co, C1 are
specific for a polymer and a solvent or solvent blend. Co
corresponds to the Tg of the polymer expressed in °K
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Measured Data
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Viscosity, cps
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Weight, %
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Temp. ºC
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Poise
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Visc. log
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T-Tg
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Tg
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DATA POINT 1
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DATA POINT 2
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Calculated Constants
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Co =
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C1 =
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Enter desired data
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Weight, %
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Delta, %
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Temperature, ºC
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Delta, ºC
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Calculated Data
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Temperature, ºC
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Weight, %
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Ws
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Tgs
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Viscosity, cps
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M.L.Williams, R.F.Landel
and J.D.Ferry,
J.Am.Chem.Soc.77,3701(1955)
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L.E.Nielsen, Polymer Rheology, Marcel Dekker,
1977,pp.33,74,133
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