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Polyethylene - U.H.M.W. ( UHMW PE )

Material Information

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We stock and supply the following standard forms:
Fabric Fibre Film Granule Powder Rod Sheet
Fabric Fibre Film Granule Powder Rod Sheet

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Common Brand Names:
Hostalen GUR, Stamylan UH
 
General Description:  

See also General Information under Polyethylene - Low Density

General Description : A semi-crystalline, whitish and effectively opaque engineering thermoplastic which, chemically, is a very high molecular weight (3-6 million) HDPE. As a result it has an extremely high melt viscosity and normally can only be processed by powder sintering methods. It also has outstanding toughness and cut and wear resistance and very good chemical resistance, somewhat better than that of HDPE.

Applications include many "wear parts" (eg bottle handling machine components), gears, bearings, artificial joints and marine quay headings. Fibres of very high molecular orientation can also be made from polyethylene of very high molecular weight by gel spinning and subsequent drawing to give fibres which are reported to be up to 85% crystalline and with 95% parallel orientation. They are known as Ultra High Modulus or High Performance Polyethylene fibre (UHMPE or HPPE). A modest range of fibre, braided cord and fabrics are available from Goodfellow.

Like Kevlar, these fibres have very high tensile properties and (small) negative CTE's. On a volume basis, their tensile properties are broadly similar to Kevlar's but, on a weight basis, they are superior thanks to an almost 50% density advantage - but they are not up to the properties of carbon fibre on either basis. Their energy absorption and acoustic velocity characteristics are superior to Kevlar's both as fabric and composite. Applications are being developed particularly in the areas of ballistic protection and ropes (in the widest sense).

   

Chemical Resistance

Acids - concentrated Good-Fair
Acids - dilute Good
Alcohols Good
Alkalis Good
Aromatic hydrocarbons Fair
Greases and Oils Good-Fair
Halogenated Hydrocarbons Fair-Poor
Halogens Fair-Poor
Ketones Good-Fair

Electrical Properties

Dielectric constant @1MHz 2.3
Dielectric strength ( kV mm-1 ) 28
Dissipation factor @ 1MHz 1-10 x 10-4
Surface resistivity ( Ohm/sq ) 1013
Volume resistivity ( Ohmcm ) 1018

Mechanical Properties

Coefficient of friction 0.1-0.2
Elongation at break ( % ) 500
Hardness - Rockwell R50-70
Izod impact strength ( J m-1 ) >1000
Poisson's ratio 0.46
Tensile modulus ( GPa ) 0.2-1.2
Tensile strength ( MPa ) 20-40

Physical Properties

Density ( g cm-3 ) 0.94
Flammability HB
Limiting oxygen index ( % ) 17
Radiation resistance Fair
Resistance to Ultra-violet Poor
Water absorption - over 24 hours ( % ) <0.01

Thermal Properties

Coefficient of thermal expansion ( x10-6 K-1 ) 130-200
Heat-deflection temperature - 0.45MPa ( C ) 69
Heat-deflection temperature - 1.8MPa ( C ) 42
Specific heat ( J K-1 kg-1 ) 1900
Thermal conductivity @23C ( W m-1 K-1 ) 0.42-0.51
Upper working temperature ( C ) 55-95

Properties for Polyethylene - U.H.M.W. Chopped Fibre

Property Value
Material Dyneema&reg; Spectra A&reg; Spectra B&reg;
Density g cm-3 0.97 0.97 0.97
Extension to break % 3.5 3.5 2.7
Modulus GPa 87 120 170
Specific Modulus cN/tex 9000 12500 17500
Shrinkage @100C % <1
Specific Tenacity cN/tex 265 265 310
Thermal Conductivity @23C W m-1 K-1 20 (axial)

Properties for Polyethylene - U.H.M.W. Fibre

Property Value
Material Dyneema&reg; Spectra A&reg; Spectra B&reg;
Density g cm-3 0.97 0.97 0.97
Extension to break % 3.5 3.5 2.7
Modulus GPa 87 120 170
Specific Modulus cN/tex 9000 12500 17500
Shrinkage @100C % <1
Specific Tenacity cN/tex 265 265 310
Thermal Conductivity @23C W m-1 K-1 20 (axial)

Buy Polyethylene - U.H.M.W. on-line

We stock and supply the following standard forms:
Fabric Fibre Film Granule Powder Rod Sheet
Fabric Fibre Film Granule Powder Rod Sheet

Choose a form to search our on-line catalogue  

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