Extrusion International 5-2025

67 Extrusion International 5/2025 Alongside proven solutions for mechanical plastics recycling, Co- perion realizes plants for chemical plastics recycling. This process con- verts plastic waste back into high- quality raw materials, potentially making unlimited recycling possi- ble. So far, the process is energy in- tensive and does not always result in high-quality products. Using catalysts could play an important role in the continued improvement of end product quality and process ef ciency. The University of Utrecht’s re- search project is dedicated to pre- cisely this challenge. The STS 25 Mc 11 twin screw extruder, being installed there to carry out the ex- periments, processes waste plas- tic, shredded or compacted, with two co-rotating screws in a closed process section. Together, inten- sive dispersion and high shear in- troduce a great deal of mechanical energy into the material. The plas- tic is energy-ef ciently melted – an advantage that is particularly important in chemical recycling. Moreover, the extruder achieves a very high mixing effect with its twin screws. The catalysts being im- plemented in this research project are distributed absolutely homo- geneously throughout the plastic melt and can fully develop their in- tended effect. In conventional pyrolytic process- es, the hot plastic melt is prepared within the twin screw extruder for the next step in chemical process- ing: pyrolysis. There, in an oxygen- free environment, the plastic is broken down to its chemical build- ing blocks. The temperature of the pyrolysis can be lowered thanks to the ef cient use of catalysts, as Vollmer’s team has shown in pre- liminary work. Said Dr. Ina Vollmer regarding her research assignment: “Using the ex- truder, we can achieve an ef cient use of the catalyst. Still, our vision is to allow pyrolysis to take place even in the extruder. We can achieve this by exploiting the mechanical-chem- ical reaction that occurs within the twin screw extruder, and speci - cally convert the polymer at lower temperatures than have previously been necessary for pyrolysis. Mix- ing with high shear in the extruder has a very positive effect on the use of catalysts. We are convinced that we can direct the chemical recycling process more precisely using lower temperatures, and this will lead to purer products while at the same time having the potential to revo- lutionize the chemical plastics re- cycling process sequence and save energy. “ Should the use of catalysts in the chemical recycling process prove its worth, the results of this research will easily be transferable to larger throughput ranges. “Following Dr. Ina Vollmer’s scien- ti c approach, we will glean system - atically researched results and draw conclusions for chemical plastics re- cycling from which we can all prof- it – recyclers and processors as well as end users,” noted Leonid Liber, Sales Engineer at Coperion. “We are proud that our STS twin screw extruder is part of this promising re- search project, and we wish Dr. Ina Vollmer much success. We look for- ward to continued collaboration.” Coperion GmbH Theodorstr. 10, 70469 Stuttgart, Germany www.coperion.com K 2025: Hall 14, Stand 14B19 Hall 9, Stand 9B34 FGCE07, Open Area "The Power Of Plastics Forum" The Coperion STS 25 Mc 11 twin screw extruder is part of a research project at the University of Utrecht investigating the mechanical- chemical conversion of mixed plastic waste using catalysts (Photo: Coperion, Stuttgart Germany) Chemical Recycling