ASTM D2196 Standard Test Methods for Rheological Properties of Non-Newtonian Materials by Rotational Viscometer

Get Certified ASTM D2196 Testing for Rheological Properties of Non-Newtonian Materials

ASTM D2196 is a professional test that gives quantitative rheological data for the characterization of the flow of non-Newtonian materials under controlled rotational shear. The results can be used for formulation development and manufacturing control, product comparison, quality assurance, and application performance evaluation. A competent technician prepares the sample, sets up and conditions the spindle, sets up and operates the viscometer, and records the measured response. The analyst then measures viscosity as a function of rotational speed and determines the sample’s behavior (shear-thinning or thixotropic).

• Material type: Non-Newtonian liquid and semi-liquid materials.
• Primary property: Apparent viscosity.
• Rheological behavior: Shear thinning and thixotropy.
• Measurement principle: Rotational viscometry.
• Shear-rate range: 0.1 to 50 s⁻¹.
• Test container: A 600 mL low-form Griffin beaker.
• Test methods: Methods A, B, and C provide different approaches for characterizing viscosity and structural recovery behavior.
• Units: SI units serve as the standard reporting basis.

What are the uses of ASTM D2196 testing?

ASTM D2196 testing helps users understand how varying shear affects a material’s viscosity. This data can be used to help make processing decisions, mixing decisions, pumping decisions, coating decisions, application decisions, and formulation stability decisions. Common uses include:

• Viscosity characterization: Determine apparent viscosity at controlled rotational conditions.
• Shear-thinning evaluation: Measure how viscosity decreases as rotational speed increases.
• Thixotropy evaluation: Assess structural breakdown and recovery under changing shear.
• Formulation development: Compare formulations and study the effect of ingredients.
• Quality control: Monitor rheological consistency between production batches.
• Application evaluation: Assess viscosity behavior relevant to coating and application processes.
• Process control: Identify changes in material flow behavior during manufacturing.
• Product comparison: Compare materials under standardized rotational conditions.

Which Materials Can Be Tested According to ASTM D2196?

ASTM D2196 is specifically for non-Newtonian materials that have shear-dependent viscosity. This is especially relevant if the material does not have a single viscosity value that will be suitable to describe its flow characteristics.  Materials that may be evaluated include:

• Paints and coatings
• Thixotropic coating materials
• Shear-thinning liquid formulations
• Pigmented liquid materials
• Resin and polymer-based formulations
• Adhesive and sealant-type materials, when their rheological behavior falls within the method’s applicable range
• Other non-Newtonian materials that can be appropriately evaluated with the specified rotational-viscometer configuration

Why is ASTM D2196 testing important?

The viscosity of non-Newtonian materials may vary significantly with respect to shear rate. Thus, a single viscosity measurement may not explain the material’s behavior during mixing, pumping, coating, spreading, or other processing operations. ASTM D2196 provides controlled rotational measurements that allow analysts to compare viscosity at different speeds and identify shear-dependent behavior. ASTM specifically identifies the reduction in viscosity with increasing speed as an indication of shear thinning and uses increasing/decreasing speed or recovery measurements to characterize thixotropy. The resulting rheological profile can help manufacturers control formulation consistency and understand how a product responds to the mechanical forces encountered during processing or application.

ASTM D2196 Testing Process and Data Collection

Technicians begin by identifying the material and preparing a representative sample. They establish the required test temperature and place the sample in the specified measurement container. The technician then installs the appropriate spindle, sets the required rotational conditions, and collects viscosity measurements. The analyst evaluates the viscosity response against rotational speed or shear rate. Shear-thinning behavior is reflected by a decrease in viscosity with an increase in shear. Changes in measurements when increasing and decreasing, or changes in viscosity after high shear and recovery, give information about thixotropic behavior. The report should contain the material, the test method, the instrument, the spindle/measurement configuration, the temperature, the rotational conditions, the measured viscosity values, shear-rate data if applicable, recovery observations, and other conditions that are necessary to interpret the results of the measurement.

Common Challenges and Troubleshooting

Viscosity can change considerably with temperature. The set and monitored temperature should be established and monitored by the technician prior to and during measurements. Settling, incomplete dispersion, or entrained air and/or inconsistent mixing can result in a different measured response. Technicians should take representative samples and make sure there are no uncontrolled bubbles in the samples. For a non-Newtonian material, one viscosity may not be enough to describe the material. 

• The analyst interprets viscosity measurements in relation to rotational speed or shear rate. Shear-thinning occurs when the viscosity decreases with increasing shear. The differences between upward and downward speed measurements, or viscosity before and after high shear, can be used by the analyst to characterize thixotropic response and recovery. 
• Viscosity is commonly reported in Pa·s or mPa·s, depending on the measurement range and reporting requirements. Shear rate is expressed in s⁻¹, while rotational speed may be reported in r/min when applicable. ASTM specifies SI units as the standard system.
• Technicians record the sample identification, temperature, instrument settings, rotation speed, measurement time, and measured viscosity. The viscosity profile, shear-dependent changes, recovery behavior, and any calculations/comparisons for interpretation are documented by the analysts. 
• The final report should include the name of the test method used, sample material, measurement conditions, results, and observations made that will enable other users to compare materials under similar conditions.

Link to ASTM D2196