RECYCLING RADIATION CROSSLINKED POLYAMIDE
Improving sustainability along the value chain
RESEARCH PROJECT “RAYCYCLE” : How can radiation crosslinked polyamides be recycled?
Radiation crosslinking is an important process for optimizing the mechanical, chemical and thermal properties of plastics. Radiation crosslinking significantly increases the durability of many plastic products and thus improves sustainability along the value chain. However, recycling poses a particular challenge, as the crosslinked parts of the plastic can no longer be melted. A joint research project (RayCycle) by BGS, nylon polymers, Aalen University and the Department of Polymer Technology and Polymer Physics at TU Berlin has investigated the opportunities and limits of material recycling of radiation crosslinked polyamides. The project was funded by the Federal Ministry for Economic Affairs and Climate Protection (BMWK) based on a decision by the German Bundestag.
RECYCLING PROJECT “RAYCYCLE” : PROCEDURE AND CENTRAL RESULTS
The basic approach for material recycling is to obtain a valuable filler by grinding the radiation crosslinked, unmixed polymer materials. This is added to the corresponding virgin material together with a crosslinking additive in the compounding process. The project team’s approach was therefore as follows: As the recycled products are integrated as a filler, the products must be ground and processed (particle recycling). Simple blending tests were carried out at the beginning of the test series. These already showed that new production of plastic parts was possible. Later on, regrind was produced in different particle sizes and added to the virgin material in varying percentages.
Results
The results from the RayCycle project show for the first time a technical way to recycle radiation crosslinked plastics based on PA6 and PA66, to produce compounds with different recycled content and to use them to produce high-performance products with a comparable range of properties. The tests did not show any deterioration in the thermal and mechanical analyses. On the contrary: the properties remain at the same level or are even significantly better compared to non-irradiated materials when the materials are irradiated again. This results in potential savings and opportunities for new applications. A rough estimate of the costs for recycling and manufacturing the compound was drawn up with the partners and plant manufacturers: This can result in savings of up to 15 percent of the material costs. More important, however, is the reduction in virgin material, as this has a direct effect on the carbon footprint.
MATERIAL RECYCLING (GERMAN LANGUAGE): RESEARCH PROJECT “RAYCYCLE”
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More InformationRECYCLING PROJECT “RAYCYLE”: OVERVIEW OF KEY RESULTS
Conclusion 1
Radiation crosslinked polyamides (PA6 and PA66) can be recycled.
Mechanical recycling was successfully evaluated as the currently most effective, simple and economically interesting process.
Conclusion 2
The thermo-mechanical properties of the recycled material remain the same or are significantly better compared to non-irradiated materials. The characteristic property values for material variations with different recycled content partially approach the property profile that was only processed from virgin material.
Conclusion 3
No significant “downcycling” effect can be seen with multiple recycling. The results show that there are no significant changes in any of the mechanical properties considered.
Conclusion 4
Processing by extrusion and injection molding is possible without significant process changes.
Conclusion 5
The reduction in new goods leads to material, energy, cost and CO2 savings.
INTERVIEW (GERMAN LANGUAGE): RESULTS OF THE “RAYCYCLE” PROJECT
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More InformationFURTHER RESEARCH : NEW WAYS OF RECYCLING RADIATION CROSSLINKED POLYAMIDES
Now that the question of the technical feasibility of recycling radiation crosslinked polyamides has been clarified and answered positively in the “RayCycle” project, the team is currently investigating new issues. For example, the development and establishment of a functioning circular economy with the stakeholders in the value chain who process, manufacture, use and sell radiation crosslinked plastics is a task that has not yet been solved. How can closed material flows for PIR (post-industrial recycling) and PCR (post-consumer recycling) be established? How does the recycled material behave at the end of its life cycle? These and other questions are the subject of further research and development work.
Radiation crosslinking: More information
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