Engineering plastics – The Manual - F.wood-supply.dk

PC
H H
C C
n
H H
CH 3
O
C
O C
CH 3
PE Structural formula PE
O
n
• Stress [MPa]
25
20
PEKEKK
15
10
5
O
0
S
0 5 10 15 20
25
• Strain [%] O
TECAFINE PE
TECAFINE PES
O
O O
O C
O C C
O n
n
TECAFINE PE
O O C
n
O
O
C
O
C
H H
O C C O
H H
n
PEEK
PE (DIN designation)
Polyethylene (PE) is a thermoplastic polymer produced by
the polymerization of ethylene. In terms of the production
quantity produced, polyethylene is among the largest group
of plastics, the polyolefins. Because of its degree of crystal-
O
CH 3
linity, CPE belongs to the group of partially crystalline CHther-
moplastics. N The most commonly used types PE (PE-HD), N
2
O
C
O
CH 3
C
CH 2
PE 5 (PE-HMW), PE 10 (PE-UHMW) and the low-density
O
polyetheylene types (PE-LD, PE-LLD) differ in terms of
their molecular weight and the degree of molecular chain
PEI
branching.
Properties
ˌˌPartially crystalline, low density
ˌˌHigh level of toughness, low strength and hardness
ˌˌVery good chemical resistance
ˌˌLow thermal stability, increasing with
O
rising molecular weight
O
C
n
ˌˌAnti-adhesive properties
ˌˌVery high thermal expansion
PEK
ˌˌVery low dissipation factor
ˌˌVery good electrical insulation
Values
TECAFINE PE (PE) TECAFINE PE 10 (PE)
T g –95 °C –95 °C
Density 0.96 g/cm 3 0.93 g/cm 3
Modulus of elasticity 1,000 MPa 650 MPa
Service temperature, long-term 90 °C 90 °C
PET
Identifying characteristics
ˌ ˌ Colour opaque / milky white
ˌˌHigh flammability
ˌˌBurns with a blue flame with yellow tip
ˌˌMinimal or no O sooting O
O
ˌˌWaxy odour C
C
C
ˌˌDensity -R < N1g / cm³, floats in water N -R
n
n
ˌ ˌ Relatively soft, C can be scored with a C fingernail
O
O
ˌˌSubjectively very light to the touch
PI
Application examples
Guide rollers, chain guides, liners for silos and chutes, extraction
and filter plates, pipes for gas and drinking water,
underfloor heating systems in PE-HMW, systems for processing
and packaging frozen food, films for a variety of
H H
industries
C
C
n
CH 2 H
Summary
CH
H 3 C CH
The different polyethylene 3
types differ in terms of their molecular
weight. The crystallinity, chemical resistance, toughness
and abrasion resistance properties of these materials
PMP
improve with increasing molecular weight. Conversely,
their processability by melting becomes more difficult. Ultra-high
molecular weight polyethylenes (PE-UHMW) can
only be processed by pressing into stock shapes or direct
moulding. The benefit: semi-finished and finished products
made of PE-UHMW demonstrate low internal stress
and minimal warpage.
N
O
C
C
O
O
C
C
O
N
m
Service temperature, short-term 90 °C 120 °C
Lower service temperature –50 °C –150 °C
14