Viscosity

Inherent Viscosity (INHVIS)

Determination of inherent viscosity by solution viscosity measurements using a Ubbelohde viscometer. Measurements can be performed according to ASTM D2857 – 95 “Standard Practice for Dilute Solution Viscosity of Polymers” or an alternative specified methodology. This technique compares the ratio of the viscosity of the solution to the viscosity of the pure solvent. The polymer is first weighed and then dissolved in an appropriate solvent. The solution and viscometer are placed in a constant temperature water bath. Thermal equilibrium is obtained within the solution. The liquid is then brought above the upper graduation mark on the viscometer. The time for the solution to flow from the upper to lower graduation marks is recorded. Time measurements are performed using a minimum of three replicates on an automated system and are used to calculate the inherent viscosity.

Intrinsic Viscosity (IV)

The intrinsic viscosity can be thought of as the inverse molecular density and is generally reported in units of dL/g. This parameter provides an excellent way to examine a polymer’s shape including branching when used for comparative analysis of samples. Analysis of sample solutions of three different concentrations followed by extrapolation to zero concentration is used to determine the intrinsic viscosity. Measurements can be performed according to ASTM D2857 – 95 “Standard Practice for Dilute Solution Viscosity of Polymers” or an alternative specified methodology. Time measurements are performed using a minimum of three replicates on an automated system.

Relative Viscosity (RV)

The RV is defined as the ratio of the viscosity of the solution to the viscosity of the solvent under identical conditions. Measurements can be performed according to ASTM D2857 – 95 “Standard Practice for Dilute Solution Viscosity of Polymers” or an alternative specified methodology. The polymer is first weighed and then dissolved in an appropriate solvent. The solution and viscometer are placed in a constant temperature water bath. Thermal equilibrium is obtained within the solution. The liquid is then brought above the upper graduation mark on the viscometer. The time for the solution to flow from the upper to lower graduation marks is recorded. Time measurements are performed using a minimum of three replicates on an automated system.