QUALITY | PROCESSING


Technology advances help PCR quality


The need to ensure recycled polymer quality is being addressed by groups involved in rheology R&D, material testing, inspection and sorting and recycling technology. By Chris Saunders


Quality control in plastics recycling is a multi- dimensional challenge driven not just by practicalities and technical factors, but also market and regulatory forces. The average proportion of post-consumer recyclate (PCR) in new plastic products remains below the targets set by the EU’s Packaging and Packaging Waste Regulation (PPWR) and End-of-Life Vehicles (ELV) directives, partly due to quality versus virgin material. Finnish research organisation VTT says it is


addressing this issue by developing a new method that enables the production of high-quality recycled plastics suitable for demanding applications using an approach combining mechanical, physical, and chemical recycling, supported by advanced rheology to stabilise quality. In this process, sensors monitor the melt viscosity of the material and other factors. When the system detects variation, the composition and additives contained in the recyclate can be automatically adjusted ensuring consistent quality and keeping material properties within a defined range. “We call the process advanced rheology control,”


said Jani Pelto, a Principal Scientist at VTT who specialises in polymer materials engineering. “In practice, it’s an automated quality adjustment system that gives the industry confidence in both the quality and desired properties of recycled plastics.”


www.plasticsrecyclingworld.com Another major hurdle when dealing with PCR


materials is the presence of unwanted odours. Despite various existing technological approaches to removing odour-active substances and other volatile organic compounds (VOCs), recycled materials often still exhibit odours, severely limiting their usability. VTT has developed an in-line VOC analysis system which can be fitted to a degassing line of any twin screw extruder. It is based on an in-house developed gas sampling system connected to the vacuum line, allowing near real-time analysis using an in-line FT-IR spectrometer GT6000 Mobilis from Finnish company Gasmet Technologies. The sampling and analysis system allows for quantitative analysis of most VOCs and moisture content and the FT-IR is sensitive enough to pick up small concentrations of residual monomers such as styrene and other low molecular weight aromatics. According to Pelto, FT-IR spectroscopy offers benefits over gas chromatography and mass spectroscopic detection (GC-MS), as it is very robust and allows expedited responses. While it does not provide full identification of each chemical species per molar mass, the powerful software algorithm can efficiently deconvolute the measured sum spectra – quantifying up to 20 different targeted organic compounds selected


Main image: LyondellBasell has made


investments in its R&D


capabilities in connection with quality improvement from flakes to pellets


November/December 2025 | PLASTICS RECYCLING WORLD 21


IMAGE: LYB


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