Solution viscosity

This test method is used to determine the viscosity number of thermoplastics.

The method involves measuring the flow times of a polymer in solution as it passes through a Ubbelohde viscometer and then establishing the difference in viscosity between the polymer solution and the solvent.

The viscosity number can then be calculated taking into account the mass concentration of the polymer solution.

The viscosity number can be correlated with a polymer’s molar mass. Molecular decomposition frequently occurs when polymers are subjected to major stress, for example during processing. This effect can be quantified by calculating the viscosity number. Molecular changes due to immersion in fluids can also be detected using this method.