Scope:

This test measures the rheological properties of polymeric materials, such as resistance of a material to flow (melt viscosity), thermal stability, and sensitivity at different temperatures over a wide range of shear rates. The shear rate and temperature conditions are equivalent to the conditions met in material calendaring, molding, and extrusion. Result obtained is generally used in determining process parameters for product preparation and thermal stability study. The application of such process parameters ensures lot-to-lot quality control and evaluation of processing parameters responsible for the degradation of physical properties.

Test Procedure:

Following specifications shared by the client, temperature, shear rate, and other parameters are designated for the test. The shear sweep test determines the force required for extrusion of molten plastic through a capillary at varied shear rates. Thermal Stability is evaluated by extruding molten plastic material through a capillary after different periods of residence time in the container of the extruder.

Specimen size:

About 80 g of test polymer is required.

Data:

Shear stress and shear rate are computed and plotted to give Shear Sweep test result. The apparent melt viscosity is computed and plotted versus residence time in the Thermal Stability test.