Polyamide
is widely and successfully used for products in the electrical
and electronics
industries. Thanks to its excellent mechanical and physical
properties over a wide range of application temperatures and
its very good weather resistance, polyamide can be used to
make products for interior and external use that meet the most
stringent of demands.
As a hygroscopic material, polyamide
has the ability to absorb moisture in molecular form into the
plastic matrix. As the moisture content goes up, product properties
may change slightly, displaying increased toughness and lower
rigidity for example.
The following table shows how the moisture
content of polyamides comes into balance with the ambient air
in a normal climate of 50% relative humidity and 23°C:
 Material |
In
air (23°C/50%
rh) |
Polyamide 6 |
2 ... 3% by weight |
Polyamide
12 |
0.8
... 1.2% by weight |
|
|
To maintain a balanced moisture content, PMA recommends storing
products under the following conditions:
| Storage
temp. |
Processing
temp. |
Rel.
humidity |
| 18°C
... 30°C |
>18°C |
>30% |
|
|
|
At lower processing temperatures and in particular when subjected
to unnatural drying, corrugated pipes display increased flexural
rigidity.
In the very dry winter months the moisture balance
may go down slightly as the material releases moisture to the
environment (owing to lower rel. humidity).
Compared to natural
outdoor conditions* at around 0°C (40 … 80% rh), the
humidity in heated rooms may drop by half to
below 20% rh if no humidification is present. (Even extremely
dry regions such
as the Sahara Desert record average humidity of 20% to 60% rh.) * Central European climate
If products from an outside environment
are brought into a heated processing area, the change in climate
may suddenly cause temporary demoisturization around the edges.
After one or two days in the processing area a natural balance
will be restored.
Most PMA products have been modified to make
them immune to climate changes of this kind.
Observing this storage
recommendation ensures optimum processability and material properties.
|
