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Polyethylene - Low Density ( LDPE )

Material Information

Buy Polyethylene - Low Density on-line

We stock and supply the following standard forms:
Fiber Film Granule Powder Rod Sheet Sphere Tube
Fiber Film Granule Powder Rod Sheet Sphere Tube

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Common Brand Names:
Alkathene, Carlona, Lacqtene, Lupolen, Stamylan LD
 
General Description:  

Polyethylenes General A family of closely related commodity thermoplastics that are manufactured in large volumes in a very wide range of grades. Traditionally differentiated by their density (a good measure of degree of crystallinity), from a scientist's point of view the better distinction is the degree of chain branching. The first polyethylene, later called LDPE, was and is made by a high pressure process using a free radical initiator/catalyst and is a polymer with a high degree of chain branching. Subsequently low pressure processes using Ziegler-Natta or related catalysts were developed which produce a much more linear molecule and generally higher crystallinities. These were and are called high density polyethylene (HDPE); this technology is now used to make a family of (chemically) closely related PE's all of which are linear - ULDPE (ultra low density ..), LLDPE (linear low ...), MDPE (medium ...), HMWPE (high molecular weight ..) and UHMWPE (ultra high molecular weight ..). On the other hand, PE copolymers (e.g. with vinyl acetate or acrylates) are normally branched polymers.

General Description : A semi-crystalline (typically around 50%), whitish, semi-opaque commodity thermoplastic that is soft, flexible and tough - even at low temperatures - with outstanding electrical properties but poor temperature resistance. It also has very good chemical resistance but is prone to environmental stress cracking; it has poor UV resistance (unless modified) and poor barrier properties, except to water.

Applications include containers, chemically resistant linings, films (which are transparent if thin) for packaging etc. and electrical/electronic applications including cable insulation and cores in UHF cables.

   

Chemical Resistance

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

Electrical Properties

Dielectric constant @1MHz 2.2-2.35
Dielectric strength ( kV mm-1 ) 27
Dissipation factor @ 1MHz 1-10 x 10-4
Surface resistivity ( Ohm/sq ) 1013
Volume resistivity ( Ohmcm ) 1015-1018

Mechanical Properties

Elongation at break ( % ) 400
Hardness - Rockwell D41-46 - Shore
Izod impact strength ( J m-1 ) >1000
Tensile modulus ( GPa ) 0.1-0.3
Tensile strength ( MPa ) 5-25

Physical Properties

Density ( g cm-3 ) 0.92
Flammability HB
Limiting oxygen index ( % ) 17
Radiation resistance Fair
Refractive index 1.51
Resistance to Ultra-violet Poor
Water absorption - over 24 hours ( % ) <0.015

Thermal Properties

Coefficient of thermal expansion ( x10-6 K-1 ) 100-200
Heat-deflection temperature - 0.45MPa ( C ) 50
Heat-deflection temperature - 1.8MPa ( C ) 35
Lower working temperature ( C ) -60
Specific heat ( J K-1 kg-1 ) 1900-2300
Thermal conductivity @23C ( W m-1 K-1 ) 0.33
Upper working temperature ( C ) 50-90

Properties for Polyethylene - Low Density Film

Property Value
Dielectric Strength @25µm thick kV mm-1 200
Dissipation Factor @1MHz 0.0003
Elongation at Break % 100-700
Heat-sealing Temperature C 120-204
Initial Tear Strength g µm-1 1.2-10.3
Permeability to Carbon Dioxide @25C x10-13 cm3. cm cm-2 s-1 Pa-1 10
Permeability to Hydrogen @25C x10-13 cm3. cm cm-2 s-1 Pa-1 8
Permeability to Nitrogen @25C x10-13 cm3. cm cm-2 s-1 Pa-1 0.7
Permeability to Oxygen @25C x10-13 cm3. cm cm-2 s-1 Pa-1 2
Permeability to Water @25C x10-13 cm3. cm cm-2 s-1 Pa-1 70
Permeability to Water @38C x10-13 cm3. cm cm-2 s-1 Pa-1 120

Buy Polyethylene - Low Density on-line

We stock and supply the following standard forms:
Fiber Film Granule Powder Rod Sheet Sphere Tube
Fiber Film Granule Powder Rod Sheet Sphere Tube

Choose a form to search our on-line catalog  

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