Establishing Desorption Temperatures and Carrier Flow Rates for Polymer Titration
Set oven desorption temperatures twenty degrees below polymer degradation points while maintaining carrier gas sweep rates between forty and seventy milliliters.
Moisture Content Limits
Meaning
Material specifications that define the maximum allowable water concentration in a polymer before it enters thermal processing prevent structural defects in the finished part. Adhering to moisture content limits is necessary for resins such as nylon or polycarbonate that are susceptible to hydrolytic degradation. If the water level exceeds these specified values, the polymer chains will cleave at high melt temperatures, reducing molecular weight.
Maintaining the material below these limits preserves the mechanical performance of the moulded component.
Processing Threshold
Maximum water levels for engineering polymers are typically set between one hundred and five hundred parts per million. For moisture content limits, the exact value depends on the chemical structure of the resin and the severity of the moulding temperature. Processors must dry the material to these levels to avoid cosmetic and structural issues.
These limits are documented on the technical datasheet.
Hydrolysis Prevention
Chemical reactions between water and hot polymer chains cause a rapid decline in melt viscosity during extrusion. When moisture content limits are violated, this degradation leads to silver streaks on the part surface and a decrease in impact strength. The loss of physical properties can cause premature failure of the finished product in service.
Avoiding these defects requires systematic drying protocols.
Resin Quality
Testing incoming material ensures that the drying process has achieved the necessary dryness before production starts. Since different polymers require different drying parameters, verifying the moisture content limits prevents process instability. Quality control relies on coulometric testing.