How Moisture Content Affects Polymer Processing
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조회 3회 작성일 25-12-22 06:47
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Moisture content plays a vital role in the polymer compounding process — when exposed to ambient humidity, materials such as nylon, PET, and polycarbonate — take in water that penetrates polymer chains. This absorbed moisture doesn’t merely reside on the surface — it infiltrates the polymer matrix, causing disruptions in the melt phase.
The compounding process requires melting polymers at precise heat levels to incorporate additives effectively}. Even trace amounts of humidity in the feedstock — it transforms into gaseous water under process conditions. This steam generation creates bubbles, voids, or entrapped gas pockets, manifesting as surface blemishes, poor shine, or inconsistent texture. They reduce the part’s surface finish, and erode key physical properties, lowering fracture toughness and durability.
Moisture doesn’t just cause physical issues—it triggers molecular breakdown. For materials like PET and nylon, water initiates chain scission, a degradation pathway that fragments long-chain molecules. This chain scission reduces the average molecular weight, and diminishes the material’s ability to flow uniformly. The material loses ductility and toughness, compromising long-term structural reliability, a risk that can be catastrophic in load-bearing or تولید کننده گرانول بازیافتی safety-critical applications.
Proper pre-drying is an essential step in quality control. Most hygroscopic resins must be dried at temperatures between 80°C and 120°C, over several hours tailored to resin sensitivity and ambient moisture. State-of-the-art facilities use precision drying technologies, maintaining residual moisture under 200 ppm.
Dried material is vulnerable to rehydration during handling. Proper material management is critical after thermal treatment. Storage must involve inert gas purging, sealed bins, or climate-controlled bins. The surrounding environment’s dew point must be tracked in real time, A limited window—often under an hour—must be maintained between drying and processing.
It is a fundamental parameter that dictates product quality and process reliability. Neglecting moisture control leads to expensive scrap, rework, and downtime. It risks long-term customer relationships and compliance standards. With comprehensive moisture management systems, trained personnel, and process controls, they guarantee repeatable performance and defect-free parts.