Meaning
Determination of water content in plastic materials is standardized globally to ensure consistency in resin processing and product quality. The international standard ISO 15512 specifies several methods for measuring moisture in polyamide, polycarbonate, and other resins. This standard covers techniques ranging from manometric methods to coulometric Karl Fischer titration.
Measurement Method
Multiple technical approaches exist to quantify the trace water present within polymer pellets. When laboratories perform testing under ISO 15512, they often use method B which involves heating the sample to vaporize the water and carrier gas transfer to a titration cell. This method provides high precision for resins that are sensitive to degradation at high processing temperatures.
Another common alternative is method C which uses a pressure sensor to measure the vaporized water in a vacuum chamber. Resin buyers use these standardized protocols to verify that incoming shipments meet processing specifications.
Process Prevention
Dry material is required to prevent hydrolytic degradation during injection molding or extrusion. If a molder processes resin with a moisture content above the specified limit of the standard, the polymer chains cleave and reduce the mechanical strength of the molded part. This hydrolytic damage causes surface defects, brittle fractures, and cosmetic issues that ruin the production batch.
Implementing rigorous testing protocols avoids these expensive molding failures and reduces scrap rates.
Calibration Standard
Instrument verification ensures that measurement errors do not lead to false passes in the laboratory. Technicians calibrate the titration equipment using certified reference materials with known water concentrations. This routine check guarantees that the measured water content represents the true state of the material before it enters the production hopper.
