Alterung von Polyamid (PA)
Why Does Polyamide Age?
Polyamides (PA) are among the most important engineering thermoplastics and are used wherever high strength, wear resistance, and temperature resistance are required. Typical applications range from components in engine compartments and electrical connectors to machine components and technical housings.
Despite their excellent properties, polyamides are also subject to a natural aging process. Over time, UV radiation, heat, moisture, and oxygen alter the polymer structure and can affect the mechanical properties of a component.
The good news is that selecting the right material and applying targeted stabilization can considerably extend the service life of polyamide components.
The Main Aging Mechanisms of Polyamide
Moisture
One particular characteristic of polyamide is its ability to absorb moisture from the environment.
This water absorption affects various material properties:
- Increased impact strength
- Reduced stiffness
- Lower modulus of elasticity
- Reduced dimensional stability
Hydrolysis may also occur when the material is continuously exposed to a combination of high temperatures and moisture. During this process, the polymer chains are chemically broken down, reducing the strength of the material.
Thermal Aging
Rising temperatures accelerate chemical reactions within the polymer structure.
Thermo-oxidative degradation can occur, particularly when the material is exposed to consistently high operating temperatures. This may result in reduced strength, lower impact resistance, and a shorter service life.
UV Radiation
UV radiation contains sufficient energy to break polymer chains.
This creates free radicals that trigger a photo-oxidative chain reaction.
Typical consequences include:
- Yellowing
- Chalking
- Surface cracking
- Embrittlement
Applications intended for outdoor use therefore require effective UV protection.
Reinforced Polyamide Is Also Subject to Aging
Glass-fiber-reinforced polyamides offer:
- Greater stiffness
- Higher strength
- Improved heat deflection resistance
- Greater dimensional stability
However, it is a common misconception that glass fibers provide protection against aging.
The polymer matrix remains sensitive to UV radiation, oxygen, and heat. Only suitable additives can provide the material with lasting protection.
Conclusion
Polyamide offers excellent mechanical properties and high temperature resistance. At the same time, moisture, UV radiation, and thermal stress place particular demands on material selection.
Stabilization tailored to the specific application can slow down aging processes and preserve the long-term performance of technical PA components.
Contact us now – our team will be happy to advise you!
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How Can Polyamide Be Effectively Stabilized?
Different additive systems are used depending on the specific application.
UV Stabilizers
They protect the polymer from harmful UV radiation and reduce photo-oxidative degradation processes.
HALS Stabilizers
HALS neutralize free radicals and extend the service life of the material, particularly in outdoor applications.
Heat Stabilizers
They delay thermo-oxidative degradation during prolonged exposure to high temperatures.
Antioxidants
Primary and secondary antioxidants protect the material both during processing and throughout the component’s entire service life.