Brabender Aquatrac-V Advances Plastics Moisture Determination Beyond Karl Fischer Titration

Moisture measurement is a critical parameter in injection molding and other polymer processing operations. Even small amounts of residual water can cause hydrolytic degradation during melting. This results in chain scission, reduced molecular weight, decreased melt viscosity, surface defects, and inconsistent part quality. In addition, moisture significantly influences the rheological behavior of polymer melts. Variations in residual water content directly affect viscosity and flow behavior, leading to non-reproducible material characterization and unstable processing conditions. Reliable moisture analysis is therefore not only a quality control tool but a prerequisite for meaningful rheological evaluation.
Target residual moisture levels depend on polymer chemistry and application sensitivity. For many PA 6 grades, processors aim for moisture contents below approximately 0.08% prior to processing. For high-performance or surface-critical components, specifications typically range from 0.02% to 0.05% (200 to 500 ppm). Within this low moisture range, analytical uncertainty and environmental influences significantly impacts pass/fail decisions in drying quality control.
This application report evaluates reliable moisture determination and control in engineering plastics used in injection molding, extrusion, blow molding, thermoforming, ultrasonic welding, and related processing operations. It compares the calcium hydride method implemented in the Brabender Aquatrac-V (ISO 15512:2019 Method E) [1] with oven-based Karl Fischer titration. The focus lies on repeatability, robustness, and suitability for routine quality control, production control, R&D, particularly at low residual moisture levels in polyamides and other technical polymers.