25 - Nanocomposite-based flame-retardant polyurethane foams

Abstract

To date, polyurethane (PU) serves a major role in useful applications in medicine, construction, automobiles, and various sectors. Owing to their unique and modifiable properties, there is diversification and expansion in the production of PUs to meet the needs of the increasing global population. However, the applications of PU foams are restricted due to their high flammability, which has resulted in numerous fires, destructions, and deaths. Scientists have found the addition of flame retardants in PU to reduce their flammability as a convenient solution. The most widely used and researched flame retardants in polyurethane foams are halogenated based, which are highly efficient but toxic to the environment and living beings. And as such, some of them are banned in different parts of the world. The rapt attention of most researchers is now gradually being channeled toward efficient, cheap, and easily attainable non-halogenated flame retardants, and several possible alternatives are emerging. This chapter addresses alternate flame retardants composed of nitrogen, phosphorus, silicon, and other miscellaneous groups but mainly focuses on metal oxides and their derivatives. Metal oxides and metal-based flame retardants are attracting attention due to their non-toxicity, low cost, high mechanical and thermal properties, and improved flame retardancy. However, not a vast amount of information is available about their uses, which necessitates the need for an expansion in this area. In much detail, this chapter provides examples and describes the mechanisms by which the different types of fire retardants work in polyurethane foams. The major drawbacks of non-halogenated flame retardants are highlighted in addition to some possible solutions to facilitate their large-scale application.