Meaning
Analytical measurement techniques use heat to release volatile components and an electric charge to quantify their concentration. Vaporization coulometry is primarily used to determine the moisture content or the presence of specific elements like chlorine in polymer samples. The process involves heating the plastic until the target substance is vaporized and then carrying it into a titration cell.
Moisture Extraction
High temperatures drive the water or volatile species out of the resin matrix and into the carrier gas. In vaporization coulometry, the amount of charge required to react with the vaporized substance is measured according to Faraday law. This provides a direct and absolute measurement of the quantity without the need for external calibration curves.
Faraday Law
Calculation of the mass depends on the total electrical energy consumed during the electrochemical reaction. Because the relationship between the charge and the mass is a physical constant, vaporization coulometry is highly accurate for trace-level analysis. This precision is necessary for verifying that resin pellets are sufficiently dry before they are fed into an injection molding machine.
Technical Reliability
Direct measurement of the reaction current eliminates the errors associated with volumetric titration. Vaporization coulometry is a robust tool for quality control because it is less sensitive to environmental factors than other moisture measurement methods. The technique ensures that the moisture levels in the raw material will not cause defects like silvering or hydrolysis in the finished part.
