Polyethylene is both the simplest possible polymer structure and one of
the most versatile polymers. It consists of only CH2 in repeated units, but even
with this simple basic structure a large variety of materials can be formed
by variations in molecular weight (MW), MW distribution, branching and
co-monomer incorporation. Variations in MW can have consequences for
processing: ultra high MW is not melt processable. Long chain or short
chain branching decreases the crystallinity and leads to a lower Young's Modulus,
higher ductility, and lower density. HDPE has a low degree of branching
and a high crystallinity, leading to the highest density among the PE types
and a relatively high Young's Modulus. HDPE is a popular construction material for
containers for liquids and food, due to the good ductility, good chemical
resistance and food-safety: many PE grades are FDA approved.
The total production volume of all PE types is the highest of all polymers,
and HDPE is among the cheapest of all polymers.
Density: 0.94 - 0.97 g/cm3.
Mechanical properties: Young's Modulus from 600 to 1500 MPa. Excellent ductility.
Thermal properties: Tm in the 120-130 °C range. Tg < -100 °C.
Chemical resistance: Excellent resistance to acids and bases, good
resistance to most organic chemicals. However, at high temperatures it
can be dissolved in aromatic and chlorinated solvents.
Translucent, can be coloured in any colour.
Very good processability with injection moulding, blow moulding,
rotomolding and extrusion. Relatively high shrinkage due to the high
crystallinity. Painting and gluing is difficult due to the low surface energy.
Welding is an excellent method for joining, although some glues for PE
are available. Printing and painting are possible after surface treatments.
-Industry: Pipes and valves for industrial fluid handling, storage
jars, vessels and tanks for chemicals, waste containers,
- Infrastructure: pipes for water and waste water transportation,
gas pipes, oil transportation pipelines, geomembranes.
- Food sector: blow-moulded containers for drinks, lids and caps,
cutting boards, crates.
- Automotive sector: fuel tanks and fuel filling pipes.
- House/garden: waste containers, pipes, ponds, decking made
from wood-polymer compounds based on HDPE.
|Minimum service temperature||-35||°C|
|Maximum service temperature||85||°C|
|Dielectric loss factor||0.00065|