Polymers | Reduced Viscosity as Quality Control Parameter for Polyamides

Polyamides are important polymers used for various applications such as the production of fibers. Dilute solution viscometry can be used to determine the viscosity number, which describes the quality of the polyamide. Lovis 2000 M/ME enables simple measurements and automatic calculation of polymer parameters at the touch of a button.

Quality control of polyamides

Polyamides are polymers containing repeating amide linkages –CO–NH– and are important engineering polymers. Main known uses are fiber applications such as the production of Nylon stockings and other garments, carpets and industrial filaments.
The term Nylon is a trade name for the specific polymer polyamide 6.6. However, meanwhile this term is often used synonymously with linear aliphatic polyamides.
Since the viscosity of a polymer solution is depending on the polymer’s molecular weight, dilute solution viscometry is often performed for the quality control of polymers. With this technique, the batch to batch variability is monitored and also degradation caused by processing can be evaluated.
Reduced viscosity is an important parameter describing the quality of polyamides. It is also often referred to as the viscosity number (VN) or Staudinger function and is the parameter of interest when performing measurements according to ISO 307.
The reduced viscosity is calculated from the runtime of the pure solvent (t0), the runtime of the polymer solution (t), as well as its concentration (c). Differently put, it is the specific viscosity divided by the polymer concentration.

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