Home Education Fillers for Polymer Applications
Other Layer Silicates
While the montmorillonites have received most attention for making nanoplate fillers, other layer silicate minerals can be used. This includes kaolin itself,
Fig. 4 Schematic of the sort of cone calorimeter results obtainable from low levels of nanoclays (reproduced, with permission, from Particulate-Filled Polymer Composites (Ed Rothon R.N.), 2nd Edition, Rapra Technology, Shawbury UK, 2003)
vermiculites, and talcs. Intercalation and separation is more difficult, however, requiring more aggressive reagents and conditions and little commercial progress has occurred. It is also possible to synthesize clays that are suitable for manufacture of nanoplates. This has the advantage of higher purity, resulting in benefits such as better color and heat aging resistance in polymers, but at higher cost. One such product, a synthetic mica, has been commercially available for some time (Somasif from CO-OP Chemical Company, Japan, www.co-op.jp).
Other Nanoplate Materials
In addition to many clays and micas, there are a number of other layer minerals, both natural and synthetic, which could, in theory at least, be exfoliated to produce nanoplates. These include layer hydroxides and hydroxycarbonates (e.g., hydrotalcites).
Probably the most interesting is graphite, and the related materials graphene and carbon nanotubes and fibers.
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