Drying polymers is an important part of the injection molding or extrusion process. Plastic drying is used to minimize or eliminate the effects that may occur due to high humidity in a plastic material. The degree of effect of humidity on the quality of the part or rebar and sheet depends on the type of polymer (plastic) being molded or extruded. In this article from pakilon.com magazine, we will examine the drying of various polymers and plastic materials, its advantages and related factors.
Types of polymers in terms of moisture absorption
Each type of plastic has its own set of unique characteristics that have a certain tendency to collect moisture. When discussing the drying of polymers, they are divided into two categories:
Hygrophilic polymers
These polymers include nylon or polyamides PA, ABS ABS, acrylic, PET PET, polyurethane PU, polycarbonate and many others. These polymers absorb moisture internally and release it through the air. Any plastic that is transferred from storage to the molding machine often needs to be dried due to its hygroscopic properties. When a hygroscopic polymer material is surrounded by a warm, dry environment for a sufficient period of time, the vapor pressure outside the polymer is lower than the vapor pressure inside the polymer, so the moisture inside the granule begins to migrate to the region of low vapor pressure outside the granule. Ultimately, we end up with a bar, sheet, tube, or granule that is free of moisture.