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Over the past few decades, the topic of recycling has become increasingly prominent in the field of sustainable materials and circular economy. One significant challenge is the physical separation of different types of plastics to obtain recyclates of one plastic type as pure as possible with comparable quality and properties to those of virgin material. Given the substantial effort involved in such separation, small amounts of contamination from other plastics may be tolerated. However, these contaminations must be monitored to ensure high-level recyclate quality. In recent years, compact, low-cost ion mobility spectrometers (IMS) with high analytical performance have been developed, and have thus become widely used in a variety of sensing applications. Due to their high sensitivity, IMS are particularly suited for detecting lowest concentration levels of various compounds, as required for the detection of impurities in recyclate quality monitoring. When coupled to a miniature gas chromatograph (GC), GC-IMS reach even higher separation power while being still compact. To bring recyclate samples to the gas phase, pyrolysis (Py) is used in this work. A first feasibility study was conducted to assess the potential of such a pyrolysis–gas chromatography-ion mobility spectrometer (Py-GC-IMS) with the objective of detecting contaminations of polyethylene terephthalate (PET) in polyethylene (PE) recyclates. The study clearly demonstrates the ability to identify PET-related fingerprints while suppressing the PE background matrix by design so that Py-GC-IMS seems a promising approach for in-process monitoring PET contaminations in PE recyclates. [ABSTRACT FROM AUTHOR]

Plastic, despite its exponential increase in production and consumption, has followed mostly a linear economy approach of take, make, use, and dispose. In order to reduce the negative impacts of plastic pollution and optimize their resource efficiency, it is critical to recover plastic wastes after use and retain them within the system for a circular economy. Apart from the majority of plastic wastes generated after the use phase as post-consumer waste, there is a significant volume of plastic waste generated during the processing of the plastic products, which is known as pre-consumer or post-industrial plastic waste (depending on the source of the generation of these wastes). To design an effective recycling infrastructure globally, the manufacturers must consider the recovery and recycling of the plastic wastes generated both during the manufacture of their products as well as after the use phase. Furthermore, it is necessary to determine the technical, environmental, and economic impacts of recycling these wastes to have a business case for integrating these processes within the value chain of plastics. Based on a research project that determined the properties of pre-and post-consumer recyclates from industries, this study will highlight the approaches and challenges in evaluating the technical, environmental, and economic impacts of recycling plastic wastes. [ABSTRACT FROM AUTHOR]

In various countries, polyethylene terephthalate (PET) represents one of the plastics with a very high recycling rate. Since currently there is no analytical method enabling direct distinction between recycled PET (rPET) and virgin PET (vPET), there are various attempts to differentiate these materials indirectly. One of these approaches claims that the recycling of PET leads to polymer chain degradation, which is reflected in changed thermal, mechanical and crystalline properties, and testing of these properties can therefore be used to distinguish rPET and vPET. However, there are many sources leading to changes in the molecular structure and consequently to the changes of the above-mentioned properties of the PET. The purpose of this study is to analyze the glass transition and melting temperature, degree of crystallinity as well as bending and impact properties of 20 different commercially available PET recyclates from 14 suppliers and evaluate the results with respect to the literature values for vPET. The main results of this study show that the range of vPET properties is so broad that all of the corresponding properties of the tested rPET lie within this range. [ABSTRACT FROM AUTHOR]