Nanoparticles as Flame Retardants

There are two basic types of nanocomposites in which particles are intercalated or exfoliated. In an intercalated composite, the nanodispersed filler sfill consists of ordered structures of smaller individual particles packed into intercalated structures. Exfoliated particles are those dispersed into practically individual units, randomly distributed in the composite. Layered silicates, such as montmorillonite clays or or-ganoclays, can be used in nanocomposites. As clays are hydrophilic and polyolefins are hydrophobic, it is not easy to make nanocomposite based on polyethylene or polypropylene because of their natural incompatibility. 

Both intercalated and exfoliated nanocomposites, containing 3-5% of nanoparticles (w/w), reportedly show better or comparable flame resistance compared with plastics filled up to 30-50% with traditional flame retardants. Another way to increase flame retardancy is to combine ATH or magnesium hydroxide with organo-clays. It was reported that organoclays and some classical flame retardants, such as brominated compounds, showed a synergism between them [13]. 

In some cases only small amount of nanoparticles, such as 5% w/w, was claimed to be necessary to significantly reduce flammability of WPC. According to Ref. 

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