Sorting multilayer packaging is still a major challenge in the recycling of post-consumer plastic waste. In a 2019 Germany-wide field study with 248 participants, lightweight packaging (LWP) was randomly selected and analyzed by infrared spectrometry to identify multilayer packaging in the LWP stream. Further investigations of the multilayer packaging using infrared spectrometry and microscopy were able to determine specific multilayer characteristics such as typical layer numbers, average layer thicknesses, the polymers of the outer and inner layers, and typical multilayer structures for specific packaged goods. This dataset shows that multilayer packaging is mainly selected according to the task to be fulfilled, with practically no concern for its end-of-life recycling properties. The speed of innovation in recycling processes does not keep up with packaging material innovations.

New regulations require improvement of plastic packaging waste management to meet higher recycling rates. One solution for today's multilayers and other sorting challenges is tracer‐based‐sorting (TBS). TBS uses fluorescent tracers to provide sorting information on packagings. Industrial printing tests with tracer materials showed good printing quality. For TBS waste management feasibility studies, extensive packaging sorting plant input analyses were carried out, focusing on materials, color, label type, and label whereabouts. Sorting tests on a TBS‐modified NIR‐sorter resulted in excellent detection rates. LCA showed the reduced climate impact of TBS compared to conventional sorting technology. Implementation and transfer of TBS to other industries show high potential.

Compounding is the final processing step for quality adjustment and control before recycled thermoplastic polymer material can be introduced into production processes. Motivated by the need for higher recyclate shares, the research question is which quality problems recycling compounders are encountered in practice, where they occur, and which mitigation options might be reasonable. Therefore, an online survey with 20 recycling compounders based in Germany was conducted asking about typical processing steps and processed materials, test procedures for quality assurance, quality problems, and possibilities for reducing quality problems. Results show that compounders mainly name impurities and contaminations of the input material as challenging and the reason for quality problems. The study shows that the problems are not dependent on the material input type. Quality problems occur along the entire secondary value chain, with companies manufacturing components themselves being particularly affected. The composition determination of the input materials helps to minimize quality problems.