Meaning
Moisture analysis of polymer resins is performed by heating a sample at a single, constant temperature and measuring the liberated water vapor. Utilizing isothermal moisture extraction allows operators to quantify the volatile content of hygroscopic plastics without causing thermal degradation. The procedure verifies that resins such as polyamide or polyethylene terephthalate have been dried to their target levels before melt processing.
Thermal Profiling
An analytical instrument heats the polymer specimen to a temperature below its melting point while a dry carrier gas sweeps the released moisture to a detector. By maintaining a constant thermal environment, isothermal moisture extraction separates surface moisture from internally bound water over a timed run. Carrier gas must flow at a steady rate to ensure accurate sensor readings throughout the extraction process.
Setting the extraction temperature correctly is necessary because excessive heat can trigger polymer degradation, which generates supplementary water through chemical reactions and skews the analytical results.
Material Performance
Moulders rely on these measurement data to prevent structural and cosmetic defects caused by hydrolytic degradation during moulding. If the polymer is processed with too much water, the material undergoes chain scission, which degrades tensile strength and impact resistance. Having accurate moisture data ensures that the processed parts meet their mechanical specifications.
Operational Efficiency
Optimizing dryer cycles based on extraction data prevents the energy waste of excessive drying. In busy moulding plants, isothermal moisture extraction provides a quick, repeatable check that fits into the production schedule. Such rapid feedback loops back into the drying system to adjust temperature and airflow settings, maximizing throughput and reducing scrap.
