Müller, TorstenTorstenMüllerIbañez, Jose MaldonadoJose MaldonadoIbañezSchneider, JörgJörgSchneiderMoser, KevinKevinMoser2025-07-082025-07-082025-07https://publica.fraunhofer.de/handle/publica/48922510.1007/978-3-031-66209-6_20Mechanical recycling of polymers is an established part of the economy and recyclates are widely used already, for example, from PET bottles. However, due to the high diversity of polymers and polymer combinations, vast challenges are faced within the processing of recycled plastics and plastic waste streams such as pollutants causing bad smell, chemicals, or other impurities (e.g., other polymers and metals. This chapter will describe the obstacles faced during the recycling of polymers and the processes that had been studied in recent years to remove such contaminants. These are among others melt purification, degassing, and/or filtration, aiming at increasing the economic value and processability of plastic recyclates.enMechanical recyclingRecycling challengesMelt purificationExtrusionPolymer sortingbook article