Meaning
Standardised laboratory protocols for measuring trace moisture in plastic materials ensure the structural integrity of molded components. This analytical procedure is defined by astm d6869, which governs the coulometric Karl Fischer titration of polymers. The technique is applicable to materials with moisture levels below one percent.
Test Protocol
Moisture determination relies on heating the polymer sample to release water vapour into a titration cell. The execution of astm d6869 requires a precise temperature setting to avoid thermal degradation of the polymer matrix, which would release interfering substances. Nitrogen gas carries the vaporised moisture from the oven to the reaction vessel where it is measured.
Overheating the sample represents a major risk because it introduces organic byproducts that distort the final measurement.
Production Consequence
Excessive moisture in raw resins leads to severe defects during the injection molding process. By utilizing astm d6869 before production begins, manufacturers can prevent the formation of cosmetic splay or internal voids that weaken the finished part. Applying the test early saves the high cost of running a production line with compromised material.
Releasing a batch to the floor without this verification can result in a high scrap rate and tool damage.
Alternative Method
Loss on drying represents a simpler but less specific alternative for water determination. Unlike simpler methods, astm d6869 distinguishes water from other volatile organic compounds. This high specificity is essential for engineering resins that release non-water volatiles at processing temperatures.
The titration provides a definitive measurement of true moisture content.
