Advancing Polypropylene Recycling: A Study on Possibilities to Improve Sorting Systems

It leads to the loss of the tailor-made properties of the former grades and therefore often to a poorer performance compared to virgin grades. In particular, the low viscosity, i.e., high melt flow rate (MFR), and the poorer mechanical properties of the recyclate pose a challenge for their use in various applications. The aim of this study is to investigate how the quality of recycled PP can be improved through improved near infrared (NIR) sorting systems. Data from both a laboratory device and an industrial NIR sorting line are used together with multivariate data analysis methods and machine learning algorithms to demonstrate the ability to separate different PP types and grades. Promising results were obtained for the classification of different PP types and the separation into low and high MFR fractions.