VroniPlag Wiki

This Wiki is best viewed in Firefox with Adblock plus extension.

MEHR ERFAHREN

 Typus Verschleierung Bearbeiter Hindemith Gesichtet Untersuchte Arbeit:
Seite: 70, Zeilen: 4-18
Quelle: Gupta 1997
Seite(n): 214, Zeilen: 11 ff.
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.

 Anmerkungen The source is not mentioned. Sichter (Hindemith), SleepyHollow02