According to Plastics Recyclers Europe, even very low quantities of degradable plastics that end up in the traditional plastic waste streams have a significant impact on recycled plastics quality.
Due to the higher proportion of degradable plastics these contain, waste streams in southern Europe pose a quality issue in films with recycled content production. In a trial conducted on 1,000 tonnes of waste plastics of equivalent quality purchased qualities of from Northern Europe and Southern Europe, suppliers demonstrated substantial quality discrepancies in the recycled film.
The tests were performed on industrial lines on which first recycled plastic (from 98/2 post-consumer quality, i.e., PE film containing 98% natural and 2% coloured material) was produced, which was then converted into a film of 50-micron thickness. While the film made from the recycled plastic from Northern Europe could be normally extruded, holes and specks occurred regularly in the film produced with recycled waste coming from Southern Europe.
Next to the qualitative analysis of the holes and specs, the abrasions of the supply lines turned out to be a useful indicator, since these were batch-independent and thus could be used as a statistical average. To understand the defects and ruptures of the film, samples were analysed by IR, thermal analysis as well as via gas chromatography mass spectrometry. These analyses demonstrated that most of the degradation was due to substances used in production of degradable plastics e.g.: starch, polylactide (PLA) and/or polybutylene adipate terephthalate (PBAT).
These tests show that there is a big impact on the functionality of recycled plastics coming from Southern Europe waste films flows. Therefore, it is necessary to develop separate streams not only for bio-waste but also degradable plastics to make sure that degradable plastics do not enter waste streams of conventional plastics.
Although thick-walled recycled products (> 50 micron) can be produced from this highly contaminated material, this will impact heavily on the appearance of the products.
The push towards increasing the use of degradable plastics is expected to make this problem more acute in the future. PRE-is therefore calling on the authorities to assess the overall impact of degradable plastics on the conventional recycling streams and to establish separate collection programmes for bio-waste and degradable plastics, so as not to jeopardise efforts to work towards more circularity in plastics processing.