Coulometric Titration Baseline Drift Calibration Methods
Drift calibration isolates cell background current from true sample moisture, preventing hydrolytic degradation and avoiding false incoming resin lot rejections.
Polycarbonate Drying
Meaning
Dehumidification heating prepares amorphous thermoplastic pellets for melt processing by removing absorbed water from the polymer matrix. Effective polycarbonate drying requires heating the resin to a high temperature, typically around one hundred and twenty degrees Celsius, using a low dew-point desiccant dryer. If the resin is not sufficiently dried, the high melt temperatures will cause hydrolytic degradation.
This chemical breakdown lowers the molecular weight of the plastic, reducing its impact strength.
Thermal Treatment
Air recirculating through a desiccant bed removes moisture from the resin hopper. Complete polycarbonate drying depends on both temperature and airflow rate to ensure uniform pellet heating. If the airflow is uneven, cold pockets of damp resin will bypass the drying zone and reach the injection screw.
This bypass results in localized weaknesses and inconsistent melt density across the production run.
Moisture Limit
Resin datasheets specify the maximum allowable water content for stable melt processing. For this amorphous resin, the standard polycarbonate drying target is below two hundred parts per million. Moulding above this threshold causes a loss of optical clarity, which is a major defect for light guides or lenses.
Accurate moisture testing verifies that the material is safe to process.
Quality Defect
Inadequate drying generates surface blemishes known as silver streaks or splay.