In a previous article, we explained what xenon tests are, why they are indispensable for plastics, and which standards such as DIN EN ISO 4892-2 underpin them.
This post follows up on that with a concrete example of practical application from Polytives and Röhm. It shows how the processability of PLEXIGLAS® can be specifically improved without compromising its long-term optical stability, i.e., the weathering stability of PMMA.
This is often where the conflict of objectives lies: in many systems, increased flowability goes hand in hand with migration, yellowing, or mechanical losses. This is unacceptable for applications with high light-conducting and functional requirements – such as in lighting technology, design, or automotive engineering.
Process optimization meets material fidelity
In joint research, PMMA compounds based on PLEXIGLAS® 6N, 7N, and 8N were modified with a polymeric acrylate additive from Polytives (bFI A 3745).
What makes this special is that the additive itself is a polymer, chemically identical to PMMA. It is not low molecular weight, PFAS-based, or silicone-based. This allows it to integrate into the polymer matrix without changing the material properties.
Nevertheless, the effects on processing are clear:
- Reduction of melt-viscosity
- significant increase in MVR values of up to over 100%
- Cycle time reductions of over 20%
- Reduction in processing temperature, in some cases by up to 35 °C
- Pressure reduction of up to 50%
For processors, this means higher throughput, lower energy consumption, less wear and tear, and greater machine availability.
What happens during weathering?
To check whether these process-related advantages have a long-term effect on the material’s optical properties, PLEXIGLAS® samples were subjected for over 10,000 hours to the xenon weathering test in accordance with DIN EN ISO 4892-2 (method A).
A comparison of the zero sample with the modified variant shows
- no significant change in transmission in the visible range (400–800 nm),
- the Yellowness Index (ASTM E313) remains well below critical values even with 7% additive,
- no yellowing, clouding, or surface degradation occurs.
This shows that the weathering stability of PMMA with polymer additives is maintained even under extreme test conditions.
The relevance for developers and compounders
The combination of optimized rheology and stable optics opens up new possibilities:
- process windows become larger without material risks,
- process capability increases while flexibility also increases,
- design freedom increases (thin-walled, complex, long flow paths), with new and higher filling level concepts and new additive supplements (natural fibers, organic components, functional additives, e.g., blowing agents),
- energy consumption and CFP decrease,
- the material remains recyclable, as the solution is migration-stable and compliant with regulatory requirements.
Instead of having to choose between efficiency and durability, both goals can now be combined.
Conclusion
The example shown here proves that modern polymer additives not only accelerate processes, but also pass long-term tests under light, heat, and moisture.
Further information
We will be happy to provide you with the complete technical article with all diagrams and detailed values upon request.
If you would like to check the optimization potential of your process, we would be happy to discuss this with you directly.
Contact us – we would be happy to discuss your application personally.
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