Recent Advancements in Flame-Retardant Polyurethane Foams: A Review

In modern society, the multifarious polymeric material polyurethane (PU) is used in household appliances and commercial sectors. Statistics shows the usage of PU as rigid and flexible foams is the highest among different PU-based materials. Industrially viable synthesis, tailor-made porosity and pore morphology, robustness to micro-organisms, weathering, hydrolytic degradation, and resistance to a wide range of chemicals are the excellent attributes of PU foams. Despite achieving significant attention in academia and industries, the prominent tendency to fire-catching or flammability and rapid-fire spread on ignition are the serious concerns of PU foams at their end-use. The figures on home fire accidents and associated fire injuries, loss of civilians, and properties primarily due to fire-catching of furniture are highly devastating. Therefore, a large volume of efforts has been dedicated to decorating flame retardancy in PU foams using a wide range of flame retardants (FRs) (in-situ or post-synthesis). Hence, the focus of this review is to summarize various FRs for rigid and flexible PU foams. The mechanism of flame retardancy, advantages and limitations of various FRs, and the past decade’s advancements achieved concerning the flame retardancy of PU foams have been explored.