PET vs. PPS Yarns for Dryer Fabrics

In demanding dryer sections, hydrolysis weakens yarn integrity under high heat and humidity, shortening fabric life and raising costs. Hot pockets (>150°C) intensify this risk, requiring materials that balance durability with performance.

This article compares PET vs. PPS yarns and key monitoring practices to limit thermal breakdown. 

1. PET Yarns: Enhancing Standard Durability: Polyester (PET) yarns offer cost-effective permeability for most dryer applications but degrade via hydrolysis in steam-rich environments, leading to brittleness and cracks after 6-12 months. Incorporate hydrolysis-resistant masterbatch additives to boost lifespan 2-4 times under 100-170°C conditions, preventing edge weakening without full material overhaul.[1]

2. PPS Yarns: Superior Heat and Hydrolysis Defense: Polyphenylene sulfide (PPS) yarns excel in hot pockets, resisting hydrolysis up to 185°C while maintaining flexibility and strength, unlike PET's vulnerability to moisture-heat aging. This results in 2x longer service life in abrasive, wad-prone zones, reducing replacement frequency for high-humidity grades.[2]

3. Hybrid Approaches for Hot Pockets: Reinforce PET fabrics with PPS edges or full PPS construction in temperatures >150°C to target hydrolysis hotspots, enhancing overall abrasion resistance and steam expulsion without compromising permeability (300-1000 CFM). This selective upgrade minimizes thermal degradation effects like fabric distortion.[3]

4. Thermal Imaging for Early Degradation Detection: Deploy infrared cameras to monitor fabric temperatures during runs, spotting hotspots (>170°C) that accelerate hydrolysis before visible cracks form. Regular scans enable proactive adjustments to steam pressure, averting 20-30% efficiency losses from uneven drying.[4]

5. Routine Cleaning and Tension Optimization: Combat contaminant buildup—exacerbating thermal stress—via scheduled high-pressure showers and conditioner applications to preserve yarn integrity. Maintain tensions at 12-18 pli to boost drying rates without over-stressing fabrics, extending life by preventing localized overheating.[5]

PMC Centre provides unbiased consultancy to optimize Paper Machine Clothing performance—independent of fabric sales. Our data-driven expertise helps resolve issues like hydrolysis degradation with precision.

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#DryerFabrics #HydrolysisResistance #PaperMachineClothing #FabricInnovation

Sources:

[1] https://www.bonfilt.com/product/spiral-dryer-fabrics/

[2] https://czechindustrialfabrics.com/typy/dryer-fabrics-for-paper-machine/

[3] https://www.pmccentre.com/post/woven-vs-spiral-dryer-fabrics-where-to-use-which-and-why

[4] http://www.en.wfczech.cz/dryer-fabrics-667/

[5] https://www.astenjohnson.com/media/1761/expertip-1-cleaning-and-conditioning-of-dryer-fabrics.pdf