Scope:

The ASTM D6980 test involves the weight loss method for determining moisture in plastics. The moisture content of plastic is a crucial factor in producing high-quality plastic parts hence it is kept under control. Polymer resins with the optimum moisture content ensure trouble-free compounding and injection molding, as well as smooth surfaces and excellent mechanical qualities in injection-molded products. 

In plastics, the moisture content is regarded as a significant parameter, and therefore, accurate measurements are important for manufacturing plastic materials and for assuring their process quality. So, the controlled moisture level of plastic resins is critical for high-quality product manufacture.

Procedure:

The specimen is spread onto a sample pan that is balanced in a heating chamber that has been preheated and equilibrated to the specified idling temperature for ASTM D6980. The moisture is then vaporized by heating it. When the indicated weight loss falls below a rate defined in the test conditions, the analysis is complete. The overall weight loss is calculated and displayed as a  percentage of moisture. To achieve precise and accurate readings, the balance and heater of the analyzer are both calibrated to NIST standards. A set of conditions for measuring moisture is established by adjusting the analyzer’s parameter settings.

Video 01: How to select a moisture analyser for the plastic industry

Specimen size:

For ASTM D6980, the plastic is used in the form of powder, pellets, or ground material as a test specimen. 

Data:

In ASTM D6980, the moisture content is expressed as percent moisture to three decimal places, with the result converted to parts per million (PPM) as follows: 

PPM = Moisture content (%) x 10000

Conclusion:

The ASTM D6980 test involves the weight loss method for determining moisture in plastics. The moisture content of plastic is a crucial factor in producing high-quality plastic parts hence it is kept under control.