Solution viscosity / Viscosity degradation test
Viscosity describes the flowability of a material and is a measure of the average molar mass (molecular weight distribution).
Generally, viscosity measurements are used as quality checks of batch uniformity or to assess processing quality. If thermal damage and thus chain degradation occur during processing of thermoplastics, these are manifested in a change in viscosity.
In the latter case, the solution viscosity method is often used. In this method, the solution viscosity of a material is determined as a viscosity number using capillary viscometers. The test involves measuring the transit time of the dissolved polymer through a capillary. If this method is used to compare the granulate before processing with the component after processing, conclusions can be drawn about the processing via the difference in viscosity.
Depending on the polymer, different standards are used, e.g. ISO 307 for polyamides.