ASTM D 2538 Procedure for PVC Using Torque Rheometer

Procedures for employing a torque rheometer to fuse Poly(Vinyl Chloride) (PVC) compounds are outlined in ASTM D 2538 Standard Practice. To enable consistent and precise characterization of PVC compounds, it offers guidance for sample preparation, rheometer setup, testing parameters, and data interpretation. This standard supports PVC materials and their processing-related quality assurance and research.

TRUSTED BY ENGINEERS FROM

Scope:

PVC compound fusion, accomplished through heat and shear, results in a unique molten state and is covered by ASTM D 2538 Standard Practice. These properties, such as the fusion time, fusion torque, melt torque, melt viscosity, heat stability, and color stability, can be precisely measured with a torque rheometer running at a set shear and temperature.

Test Procedure:

Fusion Test Method procedure:

The ASTM D 2538 Standard Practice covers the weighing of a test chemical sample. The quick-loading chute on the roller-head mixer is set up, and the sample compound is poured in while the mixer is running. The chute is loaded with weight, including the ram. The loading chute and weight are removed when the maximum torque is indicated by the torque curve. Mixing will be continued until the melt torque reaches a stable condition.

Subsequently, the mixer will be turned off, and the bowl will be opened. The compound is removed from the bowl and the blades using the brass knife, wool, or both. For additional tests, the mixing bowl is reassembled, and the same steps are followed. Sufficient time is provided to ensure that the mixing bowl has reached equilibrium at the test temperature before it is used again because some cooling occurs when the bowl is cleaned.

Video 01: Torque Rheometer

Test Specimen:

The power mix compound is used as a test specimen in accordance with ASTM D 2538 standard practice.

Data:

Standard test protocol:protocol ASTM D 2538 Utilize the following formula to determine the sample size that should be added to the mixer:

Sample Size = V – D65% Specific gravity

where V is the mixer bowl’s volume before the rotors, and D is the volume displacement they cause.

Conclusion:

As a result, ASTM D 2538 offers crucial recommendations and standards for the fusion of poly(vinyl chloride) (PVC) compounds using a torque rheometer, enabling uniform and precise characterization of PVC materials and facilitating quality control in their processing.