1. Drying temperature: Heat is the key to opening the synergy between water molecules and hygroscopic polymers. Above a certain temperature, the attraction between water molecules and polymer chains is greatly reduced, and the water vapor is carried away by the dry air.
2. Dew point: In the vacuum dryer, the humid air is first removed so that it contains very low residual moisture (dew point). Then, reduce its relative humidity by heating the air. At this time, the vapor pressure of the dry air is lower. By heating, the water molecules inside the particles get rid of the binding force and diffuse to the air around the particles.
3. Time: In the air around the particles, it takes a certain amount of time for the absorption of heat and the diffusion of water molecules to the surface of the particles. Therefore, resin suppliers should specify the time it takes for a material to dry effectively at the proper temperature and dew point.
4. Air flow: The dry hot air transfers heat to the particles in the drying silo, removes the moisture on the surface of the particles, and then sends the moisture back to the dryer. Therefore, there must be enough air flow to heat the resin to the drying temperature and maintain this temperature for a certain period of time.
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