Polycarbonate drying

Polycarbonate (PC) is a high-performance thermoplastic widely used in applications requiring transparency, impact resistance, and thermal stability, such as automotive components, electronic housings, and optical lenses. Common Drying Methods: Warm Air Cycle Oven, Countinius disc dryer:

 

Polycarbonate (PC) is a high-performance thermoplastic widely used in applications requiring transparency, impact resistance, and thermal stability, such as automotive components, electronic housings, and optical lenses. However, polycarbonate is hygroscopic, meaning it absorbs moisture from the environment. Proper drying before processing (e.g., injection molding, extrusion) is critical to prevent defects and ensure optimal material performance—a step collectively termed polycarbonate drying.

Why Drying is Essential:

Moisture Absorption: PC can absorb up to 0.2–0.3% moisture by weight in humid conditions.

Processing Defects: Undried PC causes:

Hydrolysis: High-temperature processing degrades polymer chains via moisture-induced reactions, reducing mechanical strength.

Surface Defects: Splay marks (silver streaks), bubbles, or hazy appearance in finished products.

Dimensional Instability: Warping due to uneven cooling from trapped moisture.

Common Drying Methods:

Warm Air Cycle Oven:

RXH Warm Air Cycle Oven is a versatile, energy-efficient drying equipment for various industries, with adjustable temperatures and customizable options for diverse material processing.

Countinius disc dryer:

The material flows through the surface of the drying disc along the index helix, and the material on the small drying disc is moved to the outer edge, and falls to the outer edge of the large drying disc below the outer edge of the large drying disc, and the material on the large drying disc moves inwardly and falls into the next layer of the small drying disc from the middle of the material drop port. The size of the drying discs arranged alternately up and down, the material to flow continuously through the entire dryer. Hollow drying disc into the heating medium, heating medium form of saturated steam, hot water and thermal oil, heating medium from one end of the drying disc into the other end of the export.

Key Parameters:

Moisture Content Target: ≤0.02% (200 ppm) before processing.

Drying Airflow: Ensure uniform heat distribution (recommended: 1–2 m³/h per kg of material).

Hopper Design: Insulated, airtight containers to prevent reabsorption during drying.

Common Challenges & Solutions:

Incomplete Drying:

Cause: Insufficient time, low temperature, or poor airflow.

Solution: Use moisture analyzers for real-time monitoring.

Overheating:

Risk: Yellowing or molecular weight degradation.

Prevention: Strict temperature control and timer-based drying cycles.

Reabsorption Post-Drying:

Mitigation: Store dried PC in sealed containers with desiccants or process immediately.

Material-Specific Considerations:

Flame-Retardant PC: Requires lower drying temperatures (<120°C) to avoid additive degradation.

Glass-Filled PC: Longer drying times due to reduced thermal conductivity.

Environmental & Economic Impact:

Energy Efficiency: Modern dryers optimize energy use, reducing carbon footprint.

Waste Reduction: Proper drying minimizes scrap rates caused by defective parts.