A review paper from Ghent University, Belgium, summarises the effects of flame retardants on polymers in recycling (based on nine published papers) and possibilities for flame retardant use in recycled plastics. The paper looks at polypropylenes, polycarbonates, polyamides, polyesters and polyethylenes, in particular in WEEE (waste electrical and electronics). The review shows the complexity of plastics recycling, with flame retardants often impacting the process to some extent. Particular problems occur with inorganic FRs with relatively low decomposition temperatures (incompatible with recycling processing temperatures). Another difficulty is the decontamination of WEEE plastics containing those brominated FRs which are now restricted. On the other hand, a range of PIN FRs have shown to be effective as fire safety additives in recycled polymers.
Studies cited relevant to recycling of PIN FR polymers: Almeras et al. 2004 x 2, Turku & Kärki 2016, El-Sabbagh et al. 2013, Statler 2008 x 2, Imai et al. 2003, Dawson & Landry 2005.
“On the role of flame retardants in mechanical recycling of solid plastic waste”, L. Delva et al., Waste Management 82 (2018) 198–206 https://doi.org/10.1016/j.wasman.2018.10.030