Page 118 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Molecular Weight of Polymers 81

TABLE 3.5
Viscosities of Selected Common Materials
Substances General Viscosity (MPa)
Air 0.00001
Water 0.001
Polymer latexes/paints 0.01
PVC plastols 0.1
Glycerol 10
Polymer resins and “pancake” syrups 100
Liquid polyurethanes 1,000
Polymer “melts” 10,000
Pitch 100,000,000
Glass 1,000,000,000,000,000,000,000

TABLE 3.6
Commonly Used Viscosity Terms
Common Name Recommended Name (IUPAC) Defi nition Symbol
Relative viscosity Viscosity ratio η/η o η rel = η r
Specifi c viscosity — (η/η o ) − 1 or (η − η o )/η o η sp
Reduced viscosity Viscosity number η sp /c η red or η sp /c
Inherent viscosity Logarithmic viscosity number) ln (η r /c) η inh or ln(η r /c)
Intrinsic viscosity Limiting viscosity number Limit (η sp /c) c→0 LVN
or limit ln(η r /c) c→0

n sp /c or ln n r n sp /c

ln n /c
r

Concentration (g/dL)

FIGURE 3.23 Reduced- and inherent-viscosity concentration lines for a dilute polymer solution.

(and is known as the Mark–Houwink equation) in which the proportionality constant “K” is charac-
teristic of the polymer and solvent and the exponential “a” is a function of the shape of the polymer
in a solution. For theta solvents, the value of “a” is 0.5. This value, which is actually a measure of the
interaction of the solvent and polymer, increases as the coil expands and the value is between 1.8 and

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