Qualitative and quantitative contaminants assessment in recycled pellets from post‐consumer plastic waste by means of spectroscopic and thermal characterization

• Published in: Polymer engineering and science Vol. 63; no. 4; pp. 1126 - 1132
• Main Authors: Cozzarini, Luca, Marsich, Lucia, Ferluga, Alessio
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.04.2023; Society of Plastics Engineers, Inc; Blackwell Publishing Ltd
• Subjects: Calorimetry; Chemical properties; Contaminants; Data acquisition; DSC; FTIR; Heat measurement; Identification and classification; Infrared analysis; Infrared spectroscopy; Pellets; Plastic scrap; plastic waste; Polymer blends; Polyolefins; Quality control; Quality management; Quantitative analysis; Raw materials; Recycling; Recycling industry; Spectrum analysis; Thermal properties; Thermodynamic properties; Waste management; Canada; United States
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.26269

The complexity of any plastic recycling initiative lies in the heterogeneous nature of the post‐consumer commingled plastic waste stream: recycling treatments are challenging without prior reliable sorting. A suitable identification system should be able to recognize different plastics and blends. Nowadays, the main technique used as quality control in plastic waste sorting centers is differential scanning calorimetry, whose result can be purely qualitative or semi‐quantitative, since only the crystalline fraction is evaluated. Moreover, the time required for data acquisition is relatively long. Infrared spectroscopy is an alternative, faster technique extensively used in applied research, but not widely utilized in industry. In this work, the cross‐use of infrared spectroscopy and calorimetry is tested in a real, practical case: the quality control of recycled pellets (namely composed of polyolefins only), which represent the output of a commingled plastic recycling plant and are used as secondary raw materials for different applications. Appropriate infrared spectroscopy calibration curves were built to allow the quantitative analysis with respect to the most common polymers found in the commingled plastic waste stream; the composition and contaminants in the recycled pellets were thereby determined and tracked through different production batches through the cross‐use of the two techniques outlined above. FT‐IR spectrum of recycled pellet: each characteristic band has been associated with the corresponding polymer.