Mechanical recycling contamination risks the circular plastics economy, but quality control analytics can help
A study from the University of Manchester into the effects of polymer cross-contamination on the outcome of mechanically recycling plastics has found that the presence of contaminants radically alters degradation mechanisms.
A University of Manchester study has revealed that contamination in mechanically recycled plastics can significantly impact their quality, potentially jeopardizing the future of a circular plastics economy. When plastics like yogurt containers (made of polypropylene, PP) and milk jugs (made of high-density polyethylene, HDPE) are sorted correctly, mechanical recycling is the most environmentally friendly method of transforming plastic waste into new products.
However, poor sorting can lead to cross-contamination, which disrupts the recycling process and alters the degradation mechanisms of the plastics.
Polyolefins, including both PP and HDPE, degrade differently when mixed. While HDPE can handle a small amount of contamination, as little as 1% of HDPE in PP can change the degradation process, resulting in a recyclate with altered physical properties. These changes affect the structure-property relationships of the material, reducing its overall performance, especially in industrial reuse scenarios.
This research, published in Chem Circularity, emphasizes the need for improved sorting techniques and advanced analytical quality control measures in industrial recycling processes to maintain the integrity of recycled plastics. Professor Michael Shaver highlighted the importance of these quality controls in ensuring a reliable and sustainable polyolefin recycling system.
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