Mechanically Sustainable Starch-Based Flame-Retardant Coatings on Polyurethane Foams

Abstract

The use of halogen-based materials has been regulated since toxic substances are released during combustion. In this study, polyurethane foam was coated with cationic starch (CS) and montmorillonite (MMT) nano-clay using a spray-assisted layer-by-layer (LbL) assembly to develop an eco-friendly, high-performance flame-retardant coating agent. The thickness of the CS/MMT coating layer was confirmed to have increased uniformly as the layers were stacked. Likewise, a cone calorimetry test confirmed that the heat release rate and total heat release of the coated foam decreased by about 1/2, and a flame test showed improved fire retardancy based on the analysis of combustion speed, flame size, and residues of the LbL-coated foam. More importantly, an additional cone calorimeter test was performed after conducting more than 1000 compressions to assess the durability of the flame-retardant coating layer when applied in real life, confirming the durability of the LbL coating by the lasting flame retardancy.

An overview of the recent advances in flame retarded poly(lactic acid)

“…With the increasing concern on environmental issues and the depletion of fossil resources, bio-based FRs have received more and more attention. [144][145][146] Bio-based compounds, such as cellulose, 86,147,148 starch, [149][150][151] cyclodextrin, 30,152,153 chitosan, 154 phytic acid, [155][156][157][158][159][160][161][162] and lignin, [163][164][165] can be used as highly effective green FR additives due to their excellent char-forming ability. During the combustion process of the material, bio-based FRs promote char formation on the surface, insulate the diffusion of oxygen and heat and inhibit further combustion.…”

Clays as Inhibitors of Polyurethane Foams’ Flammability

“…As mentioned above, except for the chitosan, another renewable and bio-based material that can be applied in LbL flame retardant coatings for polyurethanes is starch. Choi et al [202] used it to prepare simple starch/MMT bilayer LbL coatings using sprayassisted assembly. The efficiency of the coating comprised of five bilayers was confirmed by a 22.7% drop of pHRR and a 52.7% reduction of THR comparing to the uncoated foam.…”

Effects of ammonium polyphosphate and casein on the properties of poly (lactic acid)

“…Generally, bio‐based FRs are modified to produce bio‐based materials or mechanically blended with other high‐efficiency FRs. Studies have found that biomacromolecules such as cellulose, lignin, phytic acid, chitosan, and starch can be used in PLA to improve flame retardancy 35–38 …”

“…Studies have found that biomacromolecules such as cellulose, lignin, phytic acid, chitosan, and starch can be used in PLA to improve flame retardancy. [35][36][37][38] Casein is the most important protein in mammals and is a phosphoprotein. Furthermore, it has attracted the attention of researchers as a bio-based FR.…”