Ecofriendly flame retardant fillers: natural magnesium hydroxide and aluminum hydroxide produced by milling

Unwanted fires account for significant losses to life and property and organic polymers fuel their vast majority. Since the flammability of a material is not an intrinsic property, changing the material composition, for example by the addition of a fire retardant, will also change its reaction to fire behavior, hence reducing fire losses, fire injuries, and deaths. A wide variety of flame-retardant additive compounds is in use, enabling materials with an otherwise poor fire performance to fulfill regulatory fire performance criteria.1 Flame retardancy of polymers is often achieved by the addition of compounds containing elements such as halogens, nitrogen, or phosphorus, but the combustion products are toxic compounds such as acid gases, HCN, and environmental toxins. For this reason, in the last decades, the research of the scientific community is focused on the development of “greener” flame retardant systems able to minimize toxic products and environmental hazards by using selected metal hydroxides.2-5 Their fire retardancy is primarily a result of a strongly endothermic decomposition with the release of water, and they do not introduce any corrosive or potentially toxic substances. Aluminum and magnesium hydroxides (ATH and MDH) are the most effective products. In this regard, Nuova Sima srl was a pioneer in the production of natural MDH (Hydrofy) by milling the mineral Brucite.6 Nuova Sima srl produces also ATH (Alufy) by milling an intermediate product of the Bayer process. Nuova Sima products list comprises a great variety of materials with different particle size and their research activity is centered on the development of new surface modification both to improve the compatibility between such mineral fillers and polymers and to optimize the effect on mechanical and electrical properties.