Extrusion International 4-2024

40 Extrusion International 4/2024 PLASMA COATING – FROM THE RESEARCH Use of Recyclates in Food Contact-Method Development for the Validation of Plasma-Induced Barriers Due to the increasing use of plastics in recent years, the demand for recycling processes has grown in order to reintroduce plastics into the circular economy after their application. The ultimate goal of a recycling process is the consistency of the quality of the recycled plastics comparable to the original product. In addition to many physical and chemical properties, such as the chain length and the rheological behavior of the polymer, the fluctuating contamination of a recycled plastic limits the corresponding field of application. Especially property changes of toxicity and odorous smell reduce the use of recyclates of all art. A. Cetin, R. Dahlmann Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University R ecycled streams of everyday plastics contain residual impu - rities, making them unsuitable for use as food contact materials. In order to assess and limit the safety and potential hazards of possible contaminants in recyclates, the ap - plicability of recyclates and recyclate technologies are specified by Euro- pean regulations and authorities. In order to enable recycling streams of plastics after the application phase in everyday use as food contact materials in the form of recycled plastic food packaging, difeerent strategies are applied. One possible strategy to this problem is barrier development of a glassy layer on recyclates using plasma enhanced chemical vapor deposition (PECVD), which can potentially prevent mi- gration of contaminants through barriers. To evaluate impurities and their migration from recycled plastics and possible barrier ef - fects of the PECVD layers, a novel contamination approach for virgin materials is introduced. Further, an analysis chain regarding migration evaluation by gas chromatography coupled mass spectrometry (GC/MS) and a starting point for barrier de - velopments are discussed. Circular economy of plastics In the last decades ideological changes of industrial approaches resulted in a higher demand of eco - logical thinking [Pfa22, VPA+22, YLC+21]. One particular aspect re- garding plastics is the integration of plastic waste as a valuable pier for futures products due to their expo - nential consumer growth [Ber22, GPSB23]. Packaging plastics hold the largest stake in the distribution of the worlds global plastics applica- tion by 44%. Further comparing the distribution of plastic types Polypro - pylene (PP) accounts for an overall 19.3%. Despite many measures of governmental sides to increase the share of recycled plastics, only 8.3% of worlds plastics production were post-consumer recycled plastics in 2021 ( see Picture 1 ) [PLA22]. In Europe a set goal for a plastics strategy is conducted to meet net zero for plastics by a carbon neutral and fully circular economy [PLA22, FW22]. The aspects of circular think- ing will determine the lifecycle of fu- ture products in terms of recycling, durability and reuse [Pfa22, GPSB23, FW22]. The post-consumer history and material stream of plastics di - rect their recycling trough energy recovery, chemical or mechanical Picture 1: World plastic origins and global distributions