Unlike post-industrial plastics recycling, dealing with known and homogenous materials, post consumer recycling (PCR) poses challenges because the feedstream is variable and contains a mixture of different polymers and additives, with differing processing characteristics (rheology). Compounding World summarises today’s offer of specialist additives, designed to address odour problems, improve processing, improve compatibility between different polymers and fillers being remixed, limit colour deterioration and restore properties of the recycled plastic. Additives specifically adapted for recycling can limit the impacts of polymer degradation during re-extrusion, improve reprocessing (lubricants, melt stabilisers) and provide final material stabilisation (including antioxidants, anti-UV, acid-scavengers). Odours in PCR plastics can come from their previous use (contact with fish or other foods) or from chemical reactions during reprocessing, are generally related to amines or sulphur compounds, and can be addressed by specific odour-neutralising additives. Masterbatchers are now proposing part or 100% PCR masterbatches, including appropriate additives.
“Additives key to upcycling”, Compounding World, October 2019 www.compoundingworld.com
See also US Association of Plastics Recyclers guidance documents https://www.plasticsrecyclers.eu/downloads