Recent Advancements in Flame-Retardant Polyurethane Foams: A Review

Abstract

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.

Surface Flame-Retardant Systems of Rigid Polyurethane Foams: An Overview

“…In the condensed phase, flame retardants accelerate the degradation of the polymer and form an insulating dense char layer on the polymer surface [ 54 ]. The dense layers reduce the heat conduction, block the entry of oxygen, and reduce the concentration of combustible gas and the generation of consistent toxic smoke, thus protecting the RPUF [ 55 ].…”

Development of bio‐based magnesium phosphate flame retardant for simultaneously improved flame retardancy, smoke suppression and mechanical properties of HDPE

“…This will also affect the processability and mechanical properties of the composite. 6 Therefore, the surface modification and synthesis of flame retardants are effective and cost-effective technologies to improve the composites' flame retardancy and mechanical properties. He et al 7 prepared an environment-friendly flame-retardant unsaturated polyester resin (UPR) material with organic magnesium hydroxide (OMH) and expandable graphite (EG).…”

“…In addition, the additional amount of metal hydroxide flame retardant is usually large (>50%) to achieve ideal flame retardancy. This will also affect the processability and mechanical properties of the composite 6 . Therefore, the surface modification and synthesis of flame retardants are effective and cost‐effective technologies to improve the composites' flame retardancy and mechanical properties.…”

Anti‐drip flame retardant poly(urethane‐imide) thin films for high‐temperature applications

“…Due to the limited number of reports on flame retardant PUIs, we took insight from the vast available literature on flame retardant polyurethanes. Flame retardancy is generally introduced in polyurethanes by the addition of various halogenated flame retardants like polybrominated biphenyls, polybrominated diphenyl ethers, hexabromocyclodecanes, dechlorane, etc 20,21 . However, these halogenated flame retardants themselves and the combustion products produced by them, such as hydrogen halides, carbon monoxide, furans and halogenated dioxins etc., pose a threat to human health and the environment 22,23 .…”

“…Flame retardancy is generally introduced in polyurethanes by the addition of various halogenated flame retardants like polybrominated biphenyls, polybrominated diphenyl ethers, hexabromocyclodecanes, dechlorane, etc. 20,21 However, these halogenated flame retardants themselves and the combustion products produced by them, such as hydrogen halides, carbon monoxide, furans and halogenated dioxins etc., pose a threat to human health and the environment. 22,23 Phosphorous-based flame retardants are increasingly being employed to impart flame retardancy to polyurethane in order to overcome the issues associated with halogenated flame retardants.…”