Issue 06/2018
bioplasticsMAGAZINE_1806
bioplasticsMAGAZINE_1806
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From Science & Research<br />
By:<br />
Jasmin Bauer,Carola Westphalen<br />
KNOTEN WEIMAR<br />
Internationale Transferstelle Umwelttechnologien GmbH<br />
Weimar, Germany<br />
Tobias Hartmann, Roman Rinberg,,Lothar Kroll<br />
Technische Universität Chemnitz<br />
Chemnitz, Germany<br />
material first underwent the automated sorting process<br />
and was then manually separated from the fractions.<br />
The following results were achieved:<br />
• Detecting and, in particular, separation of PLA materials<br />
as individual material fraction in a state-of-the-art plant<br />
is possible.<br />
• Sorting under normal conditions for lightweight<br />
packaging (PLA detection not active) approx. 9 % of the<br />
PLA input goes into the PVC fraction. Hence, PLA is<br />
classified as PVC if no PLA spectrum is active.<br />
• Small scale adaption was made by adjusting the plant<br />
technology by scanning the PLA spectra.<br />
• Positive sorting on PLA results in a sorting rate of 55%.<br />
• Positive sorting on PLA+PE/PP extracted 46% of PLA<br />
input.<br />
The generated test material (PLA fraction) was grinded,<br />
washed and the grist was purified to 90 % PLA with the help<br />
of Hamos GmbH (Penzberg, Germany) in the company’s<br />
own pilot plant. The purification took place in three stages:<br />
air separation, metal separation and plastic-plastic<br />
separation. The main contamination after the cleaning<br />
process was adhesive label residues from the yoghurt cup.<br />
As not enough input material was available for the final<br />
regranulation on an industrial plant, a test material (~ 0.8 t)<br />
Fig. 2 Input material (left), automated sorting process (right)<br />
was mixed analogous to the purified fraction. This grist<br />
was regranulated at Sysplast GmbH&Co. KG in Nürnberg,<br />
Germany on a Coperion ZSK 50MC with an Ettlingen rotary<br />
filter ERF (sieve width 250 µm) with throughputs of up to 400 kg<br />
per hour. The impurities were separated effectively and a<br />
green regranulate was obtained (see Fig. 3).<br />
The mechanical testing revealed the following losses<br />
with regard to the virgin material (Ingeo 2003D from<br />
NatureWorks):<br />
Young’s modulus -1 %<br />
tensile strength -24 %<br />
Charpy unnotched -31 %<br />
Charpy notched -17.4 %<br />
All the tests and results mentioned, as well as further<br />
experiments on the recycling of PLA, including a life cycle<br />
assessment, are detailed in the final report of the research<br />
alliance “Nachhaltige Verwertungsstrategien für Produkte<br />
und Abfälle aus biobasierten Kunststoffen” funded by<br />
BMEL in which eight partners from science and industry<br />
participated [3]. A quick overview of the most important<br />
results, as well as further links to the joint project and the<br />
partners, are summarised in the results paper “PLA in the<br />
waste stream” (download link see [4]).<br />
References:<br />
[1] European Bioplastics, nova-Institut (2017). www.biobased.eu/markets<br />
[2] https://www.fnr.de/index.php?id=11150&fkz=22019212<br />
[3] https://www.european-bioplastics.org/pla-in-the-waste-stream/<br />
[4] https://www.umsicht.fraunhofer.de/content/dam/umsicht/en/<br />
documents/press-releases/2017/pla-in-the-waste-stream.pdf<br />
www.bionet.net | www.leichtbau.tu-chemnitz.de<br />
Fig. 3: seperates impurities (left) and green PLA regranulate (right)<br />
bioplastics MAGAZINE [<strong>06</strong>/18] Vol. 13 19
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