UV-resistant plastics – UV protection, resistance & comparison
Which plastics are UV-resistant? Find out what UV resistance means and which materials such as polyamide, polycarbonate or acrylic glass are suitable for outdoor use.
Engineering plastics are used in numerous applications in industry, medical technology and construction – often outdoors as well. Here, UV radiation (ultraviolet radiation) represents a central challenge, as it can significantly impair the long-term stability, colour and mechanical properties of plastics. In this article you will learn which engineering plastics are UV-resistant, which risks exist and how you can avoid UV damage through suitable material selection and protective measures.
What effect does UV radiation have on plastics?
UV radiation has a particularly high energy and acts directly on the molecular structure of many plastics. Chemical bonds within the polymer chains are destroyed, which results in a series of ageing phenomena. Typical effects are visible yellowing or discolouration of the surface, embrittlement of the material, loss of strength and the appearance of fine cracks and surface erosion. The longer and more intensively a plastic is exposed to UV radiation, the more pronounced these damages become. Temperature, humidity and material composition also significantly influence ageing.
The intensity of the damage depends on the duration and strength of UV exposure, the ambient temperature and the respective plastic type.
What does UV-resistant mean for plastics?
UV resistance describes the ability of a plastic to withstand long-term solar radiation without significantly losing its properties. UV radiation can attack plastics and, depending on the material, lead to colour changes, embrittlement, cracks or a loss of mechanical strength.
A UV-resistant plastic remains dimensionally stable and functional even with permanent outdoor use. For this purpose, either materials that are inherently UV-stable are used or materials are stabilised against UV radiation by special additives and protective layers.
UV resistance varies depending on the plastic. Acrylic glass (PMMA), for example, has a very high natural UV resistance and is well suited for outdoor applications. Polycarbonate also achieves high resistance through UV protective coatings. Polyamide (PA6 or nylon), on the other hand, shows lower UV resistance and often requires additional stabilisation for permanent outdoor applications.
For outdoor applications such as machine covers, roofing, privacy screens or technical components, UV resistance plays an important role in material selection.
UV-resistant engineering plastics
Some engineering plastics exhibit high inherent stability against UV rays or can be modified accordingly:
Polycarbonate (PC)
Polycarbonate offers good UV stability, particularly when it is provided with a coextruded UV protective layer. It is frequently used in glazing, machine covers and roof lights, as it is impact-resistant, transparent and weather-resistant.
Polyetheretherketone (PEEK)
PEEK exhibits very high thermal and chemical stability and is also UV-resistant. Due to the high costs, however, it is predominantly used in special applications where the highest demands are placed on the material.
Polymethyl methacrylate (PMMA / acrylic glass)
Acrylic glass offers excellent light transmission and shows good UV resistance even without the addition of special protective substances. It is therefore particularly suitable for applications with high optical requirements outdoors.
Polyvinylidene fluoride (PVDF)
PVDF is highly resistant to weathering and UV radiation. The plastic is used primarily in façade technology, chemical plants and the solar industry, where permanent functionality under extreme conditions is required.
Polyamide (PA) with stabilisers
Without additives, polyamide is only conditionally UV-stable. With appropriate additives such as carbon black or HALS, however, it can be adapted for outdoor applications and then offers a good combination of mechanical load capacity and UV resistance.
Which plastics are UV-resistant?
The UV resistance of plastics differs significantly depending on the material. Some materials have a high inherent resistance to solar radiation, while others age more quickly under UV radiation or require additional protective measures.
Among the particularly UV-resistant plastics is acrylic glass (PMMA). The material remains transparent in the long term, yellows only slightly and is therefore suitable for outdoor applications such as glazing, protective covers or advertising displays. Polycarbonate also shows good UV resistance, provided it is equipped with a UV protective coating. It is therefore frequently used for multiwall sheets, roofing and technical protective discs.
HPL sheets and certain UV-stabilised polyethylene or polypropylene variants are also suitable for permanent outdoor use. They withstand weathering and UV radiation significantly better than many standard plastics.
Polyamide (PA6 or nylon) has high mechanical strength, but is only considered UV-resistant to a limited extent. Permanent UV exposure can lead to colour changes and embrittlement of the material. For long-term outdoor use, alternative materials or specially UV-stabilised versions are therefore often used.
The choice of the right plastic depends not only on UV resistance but also on temperature, mechanical load and the specific area of application.
| Plastic | UV resistance | Outdoor use |
|---|---|---|
| Acrylic glass (PMMA) | very high | very good |
| Polycarbonate (UV-coated) | high | good |
| HPL | high | very good |
| Polyamide (PA6 / nylon) | low–medium | limited |
| PE / PP | depends on additives | medium |
Protective measures against UV damage
If highly UV-stable materials cannot be used, the following measures help:
- Addition of UV stabilisers (HALS, UV absorbers, carbon black)
- Coatings or paints with UV blockers
- Coextruded protective layers (e.g. for multiwall sheets made of polycarbonate)
- Structural protection (covers, shading)
Typical applications of UV-resistant plastics
| Application | Suitable material | Properties |
|---|---|---|
| Roof lights | PC with UV protection | Impact-resistant, clear, UV-resistant |
| Façade cladding | PVDF | Weather- and UV-resistant |
| Outdoor lights | PMMA | Light-stable, weather-resistant |
| Machine protection | PA + stabilisers | Robust, UV-protected |
| Solar industry | PEEK / PVDF | High-performance materials |
Is polyamide UV-resistant?
Polyamide (PA6) has good mechanical properties and is frequently used for technical components. With regard to UV resistance, however, the material shows limitations. Permanent solar radiation can lead to colour changes, surface ageing and increasing embrittlement.
For outdoor applications, standard polyamide is therefore only conditionally suitable. UV-stabilised variants or alternatively plastics with higher natural UV resistance are often used, for example acrylic glass or coated polycarbonate. The specific suitability depends on duration of use, weathering and mechanical load.
Is nylon UV-resistant?
Nylon is the common name for polyamide and fundamentally has the same properties. Standard nylon is therefore only considered UV-resistant to a limited extent. Long-term UV radiation can age the material and lead to colour changes as well as reduced strength.
For short-term outdoor use, nylon can be suitable. For permanent solar radiation, however, UV-stabilised polyamide types or materials with higher natural UV resistance are recommended. The selection of the right material should always be matched to the respective application and load.
Influence of ageing on properties
UV-related ageing affects not only the external appearance of engineering plastics but also changes key material properties. The degradation of the polymer structure can lead to reduced electrical insulation performance, which is particularly problematic in electrical engineering. Sliding properties also change – surfaces become rougher, which leads to increased wear in moving components. Chemical resistance is also impaired, as microcracks or porous structures create areas of attack for chemicals or moisture.
In safety-critical applications – for example in mechanical engineering, vehicle construction or housings of electrical components – regular visual inspections, material tests or the selection of particularly UV-resistant variants are essential. A lack of UV resistance can lead not only to failures but also to considerable safety risks.
Selection criteria for UV-resistant plastics
When selecting suitable materials for UV-exposed applications, you should consider the following points:
- Duration of outdoor use
- Temperature range
- Mechanical requirements (impact strength, elasticity etc.)
- Transparency or colouring
- Cost and availability
FAQ – Frequently asked questions
Which plastics yellow particularly quickly under UV radiation? Polystyrene (PS), ABS and standard polyamides without stabilisers show particularly rapid optical and mechanical ageing under UV influence.
Are black plastics automatically UV-resistant? Not automatically – but carbon black as a colouring agent often acts as an effective UV absorber. Nevertheless, the UV stabilisation should be checked in the data sheet.
How do I recognise whether a plastic is UV-stable? Manufacturers state in the technical data sheets whether a material is UV-stabilised. Certifications (e.g. ISO 4892) also provide indications of UV resistance.
What is the difference between UV-stable and UV-resistant? UV-stable means that the plastic has been protected against UV light by additives. UV-resistant means that the material is inherently resistant to UV radiation.
Conclusion
UV radiation represents a serious burden for many engineering plastics – both optically and functionally. Anyone who relies on permanent performance, safety and weather resistance should proceed particularly carefully when selecting materials. UV-resistant plastics such as PC, PVDF or PEEK as well as targeted protective measures such as stabilisers, coatings or structural shading can considerably extend the service life of technical applications outdoors. A well-founded selection, supplemented by regular inspection and maintenance, ensures that plastics function reliably even under intensive solar radiation.
