Stability Assessment of a Polymeric Brominated Flame Retardant in Polystyrene Foams under Application-Relevant Conditions

The flame retardant (FR) BLUEDGE polymeric flame retardant (PFR) has been in use since 2011 and was developed as a replacement FR for hexabromocyclododecane in polystyrene (PS)-based insulation foams. To better understand the degradation behavior of the PFR used within PS foams, we examined the degradation of PFR under application-relevant conditions. Thermo-oxidative and photolytic pathways represent the most relevant degradation pathways. Separately, both the thermal and oxidative degradations of PFR at ambient conditions were shown to be negligible based on kinetic models of thermogravimetric analysis data obtained at elevated temperatures; the models predict that it would take 100 years to degrade 1% of PFR at 50 degrees C and 1000 years at 20 degrees C. Photodegradation was shown to degrade PFR after accelerated ultraviolet (UV) aging/exposure. UV radiation did not significantly penetrate the foam insulation (<2000 mu m); the degradation process took place primarily at the surface. The molecular weight of the polymer changed with degradation, but there was minimal loss of bromine from the foam with degradation. The data from the liquid chromatography-mass spectrometry analysis focused primarily on several small-molecule polar products formed, which included two brominated species. These species were predicted using computer-based modeling to be biodegradable, to not be persistent in the environment, and to exhibit a low toxicity to aquatic organisms.

Automated summary

This study investigated the degradation behavior of the polymeric flame retardant BLUEDGE used in polystyrene foams, revealing that thermal-oxidative and photolytic pathways are the main degradation pathways, with UV degradation primarily occurring at the surface. Changes in polymer molecular weight were observed during degradation, but minimal bromine loss was detected in the foam.