PE-UHMW (Polyethylene, ultra high molecular weight)

Strengths

Short term operating temperatures from -268 to +150 °C (-450 to +300 °F), higher continuous service temperature than other PE grades. Outstanding toughness and cut and wear resistance, good friction properties, good low temperature impact resistance. Fibers can be produced with very high tensile strength (1-5 GPa) and good elastic modulus.

Limitations

Difficult to process (generally not melt processable except for special grades), difficult to join.

Typical uses

Can and bottle handling machine parts, moving parts on weaving machines, bearings, gears, artificial joints, chutes and slides for directing particulate solids, butcher’s chopping boards and edge protection on ice rinks. Fibers are used in high performance sailcloth.

Compositional summary

(CH2-CH2)n, typical n=100,000-250,000.
Material family	Plastic (thermoplastic, semi-crystalline)
Base material	PE-UHMW (Polyethylene, ultra high molecular weight)
CAS number	9002-88-4

Effect of composition

Cross-linking improves already good abrasion resistance.

Processing properties

Forming

Low flow rate requiring high injection pressures, only special grades can be injection molded (and then only for parts up to ~1kg), otherwise very difficult to melt process. High pressure for extrusion (up to 3000 bar), can produce fibers, mainly compression molding.

Machining

Easy to machine.

Joining

Difficult to bond. Very difficult to weld (ultrasonic and radio freq. not possible), suitable for friction stir welding though worse bond strength than conventional friction methods.