Characterization and optimization of odors in plastics and recyclates

Shredded plastic recyclates in various laboratory glasses
The odor analysis detects and removes disturbing aromas

Odor of plastic recyclates limits their use
In addition to price and performance attributes, aspects such as sustainability and the effective use of resources are becoming increasingly important factors when selecting a particular packaging system or packaging material. Global initiatives such as the Circular Economy approach of the McArthur Foundation and national legislation (Packaging Act) are demanding higher recycling quotas and the use of high-quality recyclates in new products, particular in the packaging industry. However, contaminated plastics from mixed post-consumer packaging waste are a major hurdle for the circular economy because existing purification and recycling processes often cannot produce the recyclate quality required by the packaging industry. Issues include the mechanical and processing properties of the recyclates and increasingly also their odor profiles.

Development of methods for removing odors from plastic recyclates
The objective of this research project is to develop methods to effectively remove odorous contaminants. A key aspect of the work is identifying the chemical structures of the odorous compounds. The project work covers sensory evaluation of specimen materials by a trained sensory panel and also chemical-analytical olfactory tests in order to characterize the odorous compounds in plastic waste and recyclates. This will allow the precursor molecules to be ultimately identified and possible reaction pathways and sources of the odorous compounds. Working with industrial partners, this fundamental knowledge will then be utilized to develop customized solutions for optimization or minimization of the odors of recyclates.

In addition to analyzing odors in packaging waste and recyclates, odorous substances in waste and recycled products in other industries will also be monitored, for example in the automotive industry.

Publications: Strangl, M., Ortner, E., & Buettner, A. (2019). Evaluation of the efficiency of odor removal from recycled HDPE using a modified recycling process. Resources, Conservation and Recycling, 146, 89-97. DOI:10.1016/j.resconrec.2019.03.009
  Strangl, M., Schlummer, M., Maeurer, A., & Buettner, A. (2018). Comparison of the odorant composition of post-consumer high-density polyethylene waste with corresponding recycled and virgin pellets by combined instrumental and sensory analysis. Journal of Cleaner Production, 181, 599-607. DOI:10.1016/j.jclepro.2018.01.137
  Strangl M., Fell T., Schlummer M., Maeurer A., Buettner A., Characterization of odorous contaminants in post-consumer plastic packaging waste using multi-dimensional gas chromatographic separation coupled with olfactometric resolution. J. Sep. Sci. 2017, 40, (7), 1500-1507, DOI:10.1002/jssc.201601077
Lectures: M. Strangl, T. Fell, M. Schlummer, A. Mäurer, A. Büttner. Monitoring geruchspotenter Stoffe im Recycling-Kreislauf mit Methoden der Analytischen Sensorik. Freisinger Tage – Lebensmittelverpackung im Kreislauf, Freising, Germany, 21.-22.02.2017.
  M. Strangl, T. Fell, M. Schlummer, A. Mäurer, A. Büttner. Geruchspotente Stoffe in post-consumer Kunststoffabfällen. Wissenschaftskongress „Abfall- und Ressourcenwirtschaft“, Aachen, Germany, 16.-17.03.2017.
  M. Strangl, T. Fell, M. Schlummer, A. Maeurer, A. Buettner. Characterization of odorous contaminants in different fractions of post-consumer plastic packaging waste – a comparison with corresponding regrinds and virgin materials. 19th Conference Odour and Emissions of Plastic Materials. Universität Kassel, Institut für Werkstofftechnik Kassel, Germany, 21.-22.03.2017.
  M. Strangl, T. Fell, M. Schlummer, A. Mäurer, A. Büttner. Geruchspotente Stoffe in post-consumer Kunststoffabfällen. Recycling-Technik. Dortmund, Germany, 21.-22.06.2017.
  M. Strangl, M. Schlummer, A. Mäurer, A. Büttner. Aufklärung geruchspotenter Stoffe und Monitoring von Geruchsbelastung mit Methoden der Analytischen Sensorik. 7. VDI-Tagung Gerüche in der Umwelt. Nürnberg, Germany, 15.-16.11.2017.