Chapter 7 - Chitosan-based flame-retardant polymeric materials and their applications

Abstract

In the last years, the world of flame retardance is experiencing a new trend toward the assessment of the suitability of bio-sourced products for the design of efficient flame retardants (FRs) for bulk plastics, textiles, and foams. In this context, during the last decade, chitosan, the deacetylated form of chitin, emerged as a new bio-sourced flame-retardant product, hence paving the way for new uses of this biomolecule, very far from its well-known applications. Indeed, chitosan shows several advantages and peculiarities that may justify its use for the design of new flame retardants. First, it is a good carbon source that, also combined with other selected intumescent products, can confer acceptable to high flame-retardant properties to different polymer systems. Then, this quite cheap product can be further chemically modified, hence ameliorating its flame-retardant features or its ease of dispersion within selected polymer matrices. In addition, the biomolecule can provide multifunctional features to the treated polymer systems: as an example, apart from flame retardance, it is well known to possess good antibacterial features. Finally, the use of chitosan for flame-retardant purposes is well addressed toward a green and sustainable approach, well matching the current circular economy concept. This chapter is aimed at summarizing the latest progresses regarding the use of chitosan as “key” constituent for the design of effective flame-retardant formulations suitable for bulk polymers, fabrics, and foams. The recent advances will be discussed, together with some perspectives for the next future.