Essential Drying Treatment for PC Plastic Granules

  Polycarbonate (PC) plastic is widely recognized for its exceptional performance characteristics, including high impact resistance, clarity, and thermal stability. However, a significant inherent drawback is its strong affinity for moisture, resulting in a high water absorption rate. If processed while containing excessive moisture, PC can suffer from severe hydrolytic degradation during melting, leading to issues like splay marks, bubbling, reduced mechanical strength, and poor surface finish. Therefore, a mandatory and critical pre-processing step is thorough preheating and drying. The specific drying parameters are primarily determined by the material formulation. Virgin or pure PC typically requires drying at 120°C to effectively drive off absorbed water. In contrast, modified PC grades, which may contain additives, impact modifiers, or flame retardants, are generally dried at a slightly lower temperature of 110°C to prevent additive degradation. For both types, the drying time should be a minimum of 4 hours to ensure core dryness, but must not exceed 10 hours to avoid prolonged thermal exposure and potential oxidative or thermal degradation. A reliable, practical method to judge sufficient drying is the air extrusion technique: extruding a small amount of material without rotation and observing the extrudate. A visually smooth, bubble-free, and moist-free strand indicates proper dryness. Regarding material sustainability and cost-efficiency, the incorporation of recycled PC content is entirely feasible. A typical and safe use ratio is up to 20% recycled material blended with virgin resin. For some non-critical structural or aesthetic applications, 100% recycled content can be utilized. The actual permissible amount is strictly dependent on the final product's quality and performance requirements. A critical operational note is that different masterbatches, additives, or recycled materials from various sources should never be mixed indiscriminately without prior testing, as incompatible mixtures can severely compromise the chemical, mechanical, and aesthetic properties of the finished product, leading to failure.