ASTM D5225-2017 Standard Test Method for Viscosity measurement of polymer solutions with a Differential Viscosity meter is a standard developed by the American Society for Testing and Materials (ASTM) to determine the viscosity of polymer solutions. This method is suitable for polymer solutions that are completely dissolved and do not undergo chemical reactions or degradation during testing, and the viscosity is closely related to the average molecular weight of the polymer. The standard specifies the steps for using a Differential Viscosity meter or an improved Differential Viscosity meter, including instrument preparation, Sample Handling, data collection, and result calculation. This method can provide an important basis for molecular weight analysis, quality control and performance evaluation of polymers, and is widely used in chemical industry, materials science and other fields.