Fire-retardant and thermally stable chitosan–citric acid biofoam for sustainable building insulation

The environmental problems resulting from the widespread use of conventional petroleum-based foams have prompted the pursuit of a sustainable and renewable alternative. Biobased foams based entirely on renewable resources such as chitosan (CS), citric acid (CA), sucrose (S) and phytic acid (PA) have been prepared and denoted as CCSP foam. The cooperative effects of various biobased materials on the mechanical and thermal properties, flame retardancy, and biodegradability of the resultant biofoams have been investigated. The CCSP foam was synthesized by treating CS with CA, followed by crosslinking with S and PA. The performance of the resultant foam was subsequently evaluated. The cooperative effects of the components lead to the formation of biofoams with excellent thermal insulation properties and flame retardancy with a limiting oxygen index (LOI) as high as 87.2 %. In addition, the foams exhibit low peak heat release rate (pHRR), total heat release rate (THR), peak smoke generation rate (pSPR), total smoke release rate (TSP) for combustion and low thermal conductivity, highlighting their potential as safe building materials. Besides being lightweight and biodegradable, the cooperative effects of additives present contribute to the foams exceptional compressive and structural integrity, which are equally significant properties for construction applications. Insights into the formulation of high-performance biofoams derived exclusively from sustainable and renewable materials have been provided.