Adding even small quantities of degradable plastics to plastic recyclates could lead to unexpected changes that could be described as "detrimental," according to a new study commissioned by trade body European Plastics Converters (EuPC).

The research was carried out by Dr. Wolfgang Stadlbauer of the Transfer Centre for Polymer Technology in Austria. For his study, he examined four different recycling mixtures, each containing a different quantity of degradable plastic bags, and one example of LDPE recycling material without any degradable plastic bags as ingredients. The test took six months — a period in which over 3,700 measurements were taken, EuPC said in a statement.

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At the end of the study period, Dr. Stadlbauer concluded that although all mixtures were processable, adding degradable plastic even in amounts as low as 2 percent of the total had a "significant, detrimental impact" to the recyclate quality. This impact could not only be felt in the purely mechanical properties of the recycled materials but was also visually noticeable in the new product.

The findings from the independent industrial test could once again raise the question of whether degradable plastics should be part of the recycling stream. The EuPC has urged lawmakers and waste management authorities in the European Union to increase their efforts in the separation of degradable plastics.