Magnesium hydroxide nanoparticles were produced by adding sodium hydroxide to filtered seawater to precipitate magnesium dihydroxide, calcing to magnesium hydroxide, then grinding. Calcium hydroxide nanoparticles were produced by calcining cleaned egg shells (food industry by-product). Both minerals were then tested as flame retardants in EVA (ethylene vinyl acetate) at loadings of 60%, with varying proportions of magnesium and calcium hydroxide. Results showed a reduction in peak heat release rate of over 80% for all of the mineral combinations, with a slightly greater reduction when a mixture of both minerals was used rather than 60% of one or the other. The mixture of two minerals also generated a more coherent char residue.
“Development of metal hydroxide nanoparticles from eggshell waste and seawater and their application as flame retardants for ethylene-vinyl acetate copolymer (EVA)”, M. Oualha et al., International Journal of Biological Macromolecules 128 (2019) 994–1001 https://doi.org/10.1016/j.ijbiomac.2019.02.065