Layer-by-layer Laponite, alginate and chitosan achieved self-extinguishing and halved smoke production from flexible polyu-rethane foam. Researchers first activated 25mm thick foam samples in polyacrylic acid, then soaked for five minutes consecutively in aqueous solutions of branched polyethyleneimine, chitosan, sodium alginate and laponite (a synthetic magnesium, lithium, sodium silicate clay). Nine four-stage soakings (nine quad-layers) resulted in a 46% weight increase of the foam and (in cone calorimeter) a 74% reduc-tion in peak heat release rate and a > 50% reduction in smoke re-lease rate, and inhibited melt dripping and enabled self-extinguishing in an open flame test. Impacts on the foam mechanical performance and durability of the treatment were not tested.
“Laponite-based inorganic-organic hybrid coating to reduce fire risk of flex-ible polyurethane foams”, H. Nabipour et al., Applied Clay Science 189 (2020) 105525 https://doi.org/10.1016/j.clay.2020.105525