The polyolefins are partially crystalline thermoplastic materials, characterized by good chemical resistance and good electrical insulation properties.
Because of their ease of processing the second almost all the usual technologies and seen their cheap cost, find a job now so large as to be among the most important plastics.
Watt Density ':
LDPE Low density branched From 0.92 to 0.94 g/cm3
LLDPE Linear low density From 0.93 to 0.95 g/cm3
HDPE Linear high density From 0.94 to 0.96 g/cm3
Structure:
Thermoplastic material, not polar, partially crystalline
Crystalline variable from 40% to 55% (LDPE) and from 60% to 80% (HDPE)
No water absorption
Mechanical characteristics:
Depends on the crystallinity (see density) and the degree of polymerization (see index of fusion MFI)
It can be developed into a large area compared to requirements.
Under the crystallinity can result from flexible to stiff;
Also toughness, mechanical strength, modulus of elasticity depend on the crystallinity (density).
Electrical characteristics:
Excellent electrical insulation; dielectric characteristics almost independent of the density, from the merger, the temperature and frequency.
Strong electrostatic charge (attracts dust)
Thermal characteristics:
Temperatures in excess of use:
LDPE from 80 to 95 ° C
HDPE up to 105 ° C (for a short time even higher)
approximately -50 ° C
Merger of crystals:
LDPE from 105 to 115 ° C
HDPE from 125 to 140 ° C
Burn with bluish flame, burning drips.
Resistant to:
Acids, alkaline solutions, saline solution, water, alcohols, esters, oil, petrol also HDPE; below 60 ° C almost insoluble in all organic solvents.
Not resistant to:
Strong oxidizing agents (especially heat); swelling in aliphatic and aromatic hydrocarbons for the EP low density.
If the EP is used outdoors, protected by direct solar majority to avoid a weakening (avoided if mixed carbon blacks in the 2-2.5%).