Meaning
Analytical measurement of trace moisture content in polymer resins using high precision titration or manometric techniques. Accurate low ppm water determination is essential for engineering plastics like polyamide or polycarbonate where levels above 0.02 percent cause hydrolytic degradation during molding. The process identifies water molecules trapped within the resin pellets rather than just surface moisture.
Moisture Analysis
Karl Fischer titration remains the industry standard for detecting moisture at these minute levels. While simple loss on drying methods work for bulk moisture, low ppm water determination requires a chemical reaction that is specific to the water molecule itself. An oven evaporates the moisture from the sample and carries it into a titration cell using a dry carrier gas to prevent atmospheric interference.
Signal Accuracy
Residual moisture acts as a lubricant and a chemical reactant at high melt temperatures. If the low ppm water determination indicates a value above the processing limit, the molder must extend the drying time or increase the desiccant temperature. Brittle parts and splay marks are the direct results of failing to control this variable.
Equipment Maintenance
Ambient humidity can easily contaminate the sample during transfer from the dryer to the lab. Maintaining the integrity of low ppm water determination involves using sealed containers and rapid testing protocols to ensure the data reflects the true state of the resin.
