REACTIVE COMPOUNDING | TECHNOLOGY


Reactive compounding may


close the recycling circle Compounding extruders can provide an effective means for chemical modification of polymers.Peter Mapleston reviews some of the latest developments, including new recycling ideas


The use of compounding extruders and co-knead- ers as continuous chemical reactors offers interest- ing opportunities for those looking for innovative polymer performance modification solutions. Reactive extrusion provides a well-established route to production of different types of thermo- plastic elastomers – TPVs in particular but also TPUs – and can also be employed for polyamides. More recently, it has been applied to the development of compounds with improved flame-retardant properties, and also – and this may yet prove to have the greatest long term impact on the plastics industry – to the creation of new high-quality polymer compounds from post-consumer recy- clate. This article takes a look at a few of the most


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recent developments. The Institut für Kunststofftechnik (IKT) at the University of Stuttgart in Germany has, over the years, built up considerable experience in the field of reactive extrusion, especially in the scope of increasing the molecular weight of a polymer to enable additional processing methods. One focus of its current research is the improvement of flame-retardant polyamides. “To increase flame retardancy, polyamides are usually compounded with additives like red phosphorus or halogen- nitrogenous or phosphoric molecules,” says Sinja Pagel, a Research Associate at the IKT. “However, in order to achieve an acceptable flame retardance, very high amounts of these additives are necessary.


Main image: Reactive extrusion techniques allow polymers to be chemi- cally modified to lift perfor- mance of both virgin and recycled resins


August 2019 | COMPOUNDING WORLD 29


PHOTO: POLYCOMPOUND


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