Technical document

    What is UHMW material

    2025-06-13 10:52:59 UHMW

    1. Basic Definition

    UHMW material, fully known as Ultra - High Molecular Weight Polyethylene, is a thermoplastic engineering plastic with a relative molecular mass usually above 1.5 million (commercial products commonly range from 1.5 to 10.2 million).

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    2. Performance Characteristics

    1. Excellent wear resistance: Top - notch among plastics, even exceeding some metals. Long, regular molecular chains and high crystallinity disperse stress under friction, ideal for wear parts like textile machinery shuttles.

    2. Strong impact resistance: Maintains high impact resistance at room temperature and even in extreme cold (e.g., liquid helium at -269°C). Peak impact strength at ~2 million molecular weight, suitable for low - temperature engineering.

    3. Low friction coefficient: 0.1 - 0.3 dry, 0.05 - 0.10 with water lubrication. Self - lubricating, perfect for bearings and bushings.

    4. Chemical resistance: Stable in most alkalis and acids (e.g., 80°C HCl, <20% HNO?, <75% H?SO?), except concentrated nitric/sulfuric acids. Prone to swelling in high - temperature aromatics/halogenated compounds.

    5. Weather & water resistance: Virtually zero water absorption, UV - resistant (enhanced with anti - aging agents).

    6. Other properties: FDA - approved for food/medical contact, excellent electrical insulation, ductile at low temps, non - toxic.

    3. Processing Challenges & Methods

    1. Challenge: Extremely high melt viscosity (10? Pa·s), poor flow—difficult to inject mold in pure form.

    2. Methods:
      ① Compression sintering: Primitive, low - efficiency, prone to oxidative degradation.
      ② Extrusion: Using plunger/single - screw (China’s specialized models)/twin - screw extruders for pipes.
      ③ Injection molding: Feasible with equipment modification for rollers, bushings.
      ④ Blow molding: For hollow containers and high - performance films.
      ⑤ Special processes: Gel spinning for high - strength fibers in ropes, ballistic products.

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    4. Applications

    1. Textiles: Wear parts (shuttles).

    2. Paper: Doctor blades.

    3. Packaging: Specialty packaging products.

    4. Machinery: Gears, bushings, bearings.

    5. Agriculture: Anti - wear agricultural parts.

    6. Chemicals: Seals, corrosion - resistant pipes.

    7. Food & medical: FDA - compliant components (food machinery, medical devices).

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