Highly flame-retardant bio-based polyurethanes using novel reactive polyols

Poor flame retardancy of polyurethanes (PU) is a global issue as it limits their applications particularly in construction, automobile, and household appliances industries. The global challenge of high flammability of PU can be addressed by incorporating flame-retardant materials. However, additive flame-retardants are non-compatible and depreciate the properties of PU. Hence, reactive flame-retardants (RFR) based on aliphatic (Ali-1 and Ali-2) and aromatic (Ar-1 and Ar-2) structured bromine compounds were synthesized and used to prepare bio-based PU using limonene dimercaptan. The aromatic bromine containing foams showed higher close cell content (average 97 and 100%) and compressive strength (230 and 325 kPa) to that of aliphatic bromine containing foams. Similar behavior was observed for a horizontal burning test where with a low concentration of bromine (5 wt %) in the foams for Ar-1 and Ar-2 displayed a burning time of 12.5 and 11.8 s while, Ali-1 and Ali-2 displayed burning time of 25.7 and 37 s, respectively. Neat foam showed a burning time of 74 s. The percentage weight loss for neat PU foam was 26.5%, while foams containing 5 wt % bromine in Ali-1, Ali-2, Ar-1, and Ar-2 foams displayed weight loss of 11.3, 14, 7.9, and 14%, respectively. Our results suggest that flame retardant PU foams could be prepared effectively by using RFR materials. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46027.