Meaning
Thermal extraction of volatile compounds from a solid matrix allows for the quantitative analysis of trapped moisture and additives in high-performance polymers. The method of high-temperature desorption heating drives off tightly bound water molecules from engineered resins without melting the polymer structure itself. This separation is necessary for analyzing resins that undergo hydrolysis at elevated processing temperatures, providing a reliable measure of water content in raw materials.
Analytical Mechanism
An inert carrier gas sweeps the desorbed volatiles into a titration cell or detector. Heating the polymer sample to a temperature just below its softening point accelerates the diffusion of moisture from the core of the pellets. This technique avoids the contamination of the analyzer with molten resin.
Processing Benefits
Moulders use this technique to verify the dryness of highly filled compounds before injection molding. Inaccurate moisture readings often cause cosmetic surface defects or structural weaknesses in molded parts. Validating the moisture level prevents the costly rejection of finished industrial components.
Instrument Optimization
Optimizing the gas flow rate prevents the re-condensation of volatiles on the transfer lines. Cold spots in the flow path lead to carryover effects between sequential sample runs. Keeping the transport tubing heated ensures that the entire desorbed sample reaches the sensor.
