HDPE multiple recycling proven in an experiment

For the first time, ESE has proven in an experiment under practical conditions that HDPE can be recycled at least ten times and further processed under controlled conditions.


Since the 1980s, the ESE Group has dealt with the use of recycled plastics for the manufacturing of containers for waste and recyclables. The situation in the market has changed significantly over the last few decades. Nowadays, disposable recycled materials have large fluctuations in purity and quality.

On the basis of their extensive experience in the processing of recycled HDPE in injection moulding, over the years ESE has developed innovative procedures and processes in the cleaning, additives and processing of recycled plastics. As a result, it is possible for ESE to make products from recycled plastic to the quality level of Virgin Material.

A question has remained unanswered in material science until now: How often can HDPE be processed, ground and newly processed in injection moulding procedures without that fundamentally changing the structure of the material and its characteristics?

Systematic research on recycled material is more difficult, because the materials available in the market rarely provide definitive statements about origin, initial processing, additives and product use.

For future research and development, for the first time, ESE has created the foundation in a model project under practical conditions.

Project Manager Jeanett Köhn is a post-graduate Chemistry student and has specialised in their previous research activity at the Fraunhofer Institute for applied polymer research in plastics. Together with plastic engineers in ESEs development team, she is working to align the use of recycled plastic in ESE according to the future needs and the current state of research.

With the knowledge that contamination from previous production processes, foreign polymers and contaminants from the product use falsify research results and make research practically impossible, Dr. Köhn has designed a controlled experimental setup.

HDPE Virgin Material was the starting point. They have been processed, ground and newly processed ten times in the ESE production facilities in the injection moulding process to containers for waste and recyclables. After each step, the material is analysed in cooperation with external research institutions using state of the art methods.

Only under these conditions are all the influencing factors known, the behaviour of material and additives can be assessed and are used for comparison with other materials. In this project, it can be demonstrated for the first time, that the injection moulding process and the shredding of the plastics have, in principle, no property-altering damage of the material - in at least 10 cycles.

Along with the service life of containers for recyclables of 15-20 years and the relatively low loss of material in the process, this result means that the availability of material for sustainable production from the same recycled material is secured for at least 150 to 200 years.

Of course, the ideal conditions for the experimental project are not found in reality, although the structure of the material of containers for waste and recyclables changed relatively little during its operating life. Damage by UV radiation on the outer surfaces of the containers is detectable even after years, but only on a scale of a few tenths of a millimetre. However, the initial processing requires the use of additives for the injection moulding process just as much as they are needed to offer protection thereby preventing material damage in the processing phase and as a result of UV radiation. When recycling products, further mixtures with other plastics and contamination can occur. Therefore, despite the positive test result, the controlled use of recycled materials in accordance with the highest quality is only possible with knowledge and relevant experience in the processing phase.

Decades of developments under production conditions have put us in the position to process and treat recycling material, in such a way that the quality of the products is on a par with Virgin Material. The findings of the series of experiments now allow us to engage in more targeted research and to develop further future-oriented methods.

The processing of post-consumer recycled plastic is much more sustainable than that of Virgin Material. It saves 100% crude oil and approximately 65% Co2 equivalent therefore requiring approximately 88% less energy. ESE also sees the use in this sector as an investment in the future of the company, because sustainable procurement and the demand for more environmentally friendly products are increasing worldwide.

For this purpose, ESE also has its 2- and 4-wheel container certified with the Blue Angel environmental label - as independent proof of the processing of at least 80% certified post-consumer recycled plastic.