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

Moisture absorption
Moisture or water absorption is the ability of a material to
absorb moisture from its environment (air, water). The degree
of moisture absorption depends on the type of plastic
and the ambient conditions such as temperature, humidity
and contact time. This can influence primarily material
properties such as dimensional stability, mechanical
strength and electrical properties such as electrical conductivity
and the dissipation factor.
Polyamides in particular tend to absorb higher amounts of
moisture compared to other thermoplastics.
This property results in dimensional changes and lower
strength values in finished parts. In addition, its electrical
insulating behaviour also changes. For this reason, particularly
in the case of components with narrow tolerances, the
suitability of polyamide must be examined beforehand.
Alongside polyamides, most polyimides also demonstrate
relatively high moisture absorption. With this material
group, the main consequence of this characteristic is that
the materials have very low hydrolysis resistance (humid
environment at high temperatures).
Moisture absorption 96 h [%]
0 0.1 0.2 0.3 0.4
16
15
14
13
12
TECAFLON PVDF
TECAFLON PTFE
11
10
TECAFORM AH
9
0.5
0.6
0.7
0.8
8
TECAMID 66
TECAMID 6
7
TECAPET
TECANAT
6
5
TECAPEEK
TECAPEI
TECATRON
• Linear thermal expansion [10 –5 1/K]
4
3
2
1
0
TECAFLON PTFE
TECADUR PBT GF30
TECASON P
TECATRON GF 40
TECAMID 66 GF 30
TECAPEEK
Steel
0 0.1 0.2 0.3 0.4 0.5
0.6
0.7
TECAMID 46
0.8
• Moisture absorption [%]
62