Why Moisture Content of plastic Decides Your Drying Efficiency

Why Moisture Content of Plastic Decides Your Drying Efficiency

Selecting the perfect dryer for plastic processing goes beyond capacity—it hinges on understanding the moisture content . Get this wrong, and you risk inefficiency, energy waste, and subpar products. Here’s why moisture content is the make-or-break factor in drying performance.

The Critical Role of Moisture Content in Plastic Drying

Every drying assessment starts with four key questions:

1. Material Type – What plastic are you drying?
2. Initial Moisture Content of Plastic – How wet is your material upfront?
3. Target Moisture Content of Plastic – How dry must it be?
4. Throughput – What’s your hourly output requirement?

Misjudging the moisture content  at any stage leads to:

• Extended drying times
• Higher energy costs
• Inconsistent product quality

How Plastic Type Affects Moisture Content

Not all plastics handle moisture the same:

• Hygroscopic plastics (e.g., PA6, TPU): Absorb moisture aggressively, requiring rigorous drying.
• Non-hygroscopic plastics (e.g., PP, PE): Resist moisture but still need drying for optimal processing.

Key Metrics for Moisture Content of Plastic:

• Equilibrium Moisture Content: Natural water retention in ambient air (e.g., PA6: ~3.5%, PC: ~0.15%).
• Saturated Moisture Content: Maximum water absorption (e.g., PA6 can reach 10% in humid conditions).

Real-world alert: Additives, fillers, and storage conditions alter the moisture content of plastic—never rely solely on textbook values!

Why Initial Moisture Content of Plastic Dictates Drying Effort

Compare two scenarios with PA6:

• Low moisture content (0.1%) → Drying to 0.05%: 3 hours.
• High moisture content (0.5%) → Same target: 6+ hours.

Pro Tip: For plastics with elevated moisture content (e.g., stored in humidity), pre-drying is essential to protect desiccant dryers.

(Think of it like drying clothes: A soaked towel takes twice as long as a damp one.)

Target Moisture Content of Plastic: The Precision Factor

Even with identical starting points, stricter targets demand more time:

• PC at 0.1% initial moisture:
  • Drying to 0.05%: 3 hours.
  • Drying to 0.02% (for optical grades): 4+ hours.

This is why knowing your required moisture content of plastic is non-negotiable for applications like medical devices or automotive parts.

Avoid Costly Dryer Sizing Mistakes

1. Undersized Dryers → Incomplete drying → Bubbles, weak spots, and rejects.
2. Oversized Dryers → Energy waste + material degradation from over-drying.

Golden Rule: Always test the moisture content of plastic upon arrival—supplier specs can’t account for storage or transport humidity.

Key Takeaways: Mastering Moisture Content of Plastic

1. Test First – Measure incoming material’s moisture content.
2. Define Targets – Align drying goals with your product’s specs.
3. Right-Size – Match dryer capacity to your moisture content and throughput needs.

Need Help Optimizing for Moisture Content? Our engineers specialize in tailoring drying solutions to your plastic’s unique needs. [Contact us for a free assessment].