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| Untersuchte Arbeit: Seite: 70, Zeilen: 4-18 |
Quelle: Gupta 1997 Seite(n): 214, Zeilen: 11 ff. |
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| Polymer solutions show very high viscosity which varies not only with concentration but also with molecular weight. This property of polymers has been used as a method of determining the molecular weight of polymers. A parameter called intrinsic viscosity [η] is strongly dependent on the molecular dimensions of the solute particles. Since molecular dimensions depend on molecular weight, suitable calibration curves have been developed which led to well-known relation called the Mark-Houwink equation:
Where k and a are constants and M is the molecular weight of the polymer. M may represent Mn or Mw, depending on the molecular weight average used in the calibration curve. The intrinsic viscosity [η] is defined as follow:
Where η and η0 are the viscosities of the solution and the solvent, respectively, and c is the concentration. The last expression on the right-hand side is simply to define the symbol ηsp (specific viscosity) in subsequent discussion. The intrinsic viscosity is therefore determined by plotting ηsp/c against c and extrapolating the plot to zero concentration, as shown in Figure 5.5 |
Polymer solutions show very high viscosity which varies not only with concentration but also with molecular weight. This property of polymers has been used as a method of determining the molecular weight of polymers.
A parameter called 'intrinsic viscosity' (also called 'limiting viscosity number' in modern nomenclature), denoted with brackets as [η], is strongly dependent on the molecular dimensions of the solute particles. Since molecular dimensions depend on molecular weight, suitable calibration curves have been developed which lead to a well-known relation called the Mark-Houwink equation:
where K and a are constants and M is the molecular weight of the polymer. M may represent Mn or Mw, depending on the molecular weight average used in the calibration curve. The intrinsic viscosity [η] is defined as follows:
where η and η0 are the viscosities of the solution and the solvent, respectively, and c is the concentration. The last expression on the right-hand side is simply to define the symbol ηsp (specific viscosity) in subsequent discussion. The intrinsic viscosity is therefore determined by plotting ηsp/c against c and extrapolating the plot to zero concentration, as shown in Fig. 10.8. |
The source is not mentioned. |
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