Usually for improving the strength of epoxy resins nanocalys are incorporated into it but to have proper dispersion nanoclays are often subjected to surface treatment , so in order to disperse the nanoclay in epoxy how to do the surface treatment and how to identify the suitable surface treatment element?
The most common method of nanoclay organophilic treatment is an ion exchange. You need to replace natural metal cations in the clay interlayer space by organic cations. Most frequently long alkylammonium cations are used. In some cases organic cations with OH or COOH functions at the alkyl end are employed to improve polar interactions or even covalent bonding between organoclay and polymer matrix.
There is a lot of literature on this subject, I suggest starting from this early, e.g:
Lan, T.; Pinnavaia, T. Chem. Mater. 1994, 6, 2216–2219
Zerda A. S., Lesser A. J. J. Polym. Sci. Part B: Polym. Phys., 2001, 39, 1137
Nigam V., Setua D. K.,. Mathur G. N, Kar K. K., J Appl Polym Sci 2004, 93, 2201
Kornmann X. Berglund L.A., Thomann R., Mulhaupt R., Finter J.,
Polym. Eng. Sci., 2004, 42, 1815
Kornmann X., Lindberg, H, Berglund L.A. Polymer 2001, 42, 4493
Le Pluart, L., Duchet, I., and Sautereau, H. (2005) Polymer, 46, 12267
Since the cations on the clay surface can be exchanged by other organic cations (so called intercalants), which are tailored to the polymer in which the clay would be become more compatible. This process renders the clay more hydrophobic and helps to open up the clay galleries (as the adding of the intercalant on the clay surface). This facilitates the penetration of polymer in the clay galleries then subsequently exfoliates the clay.
Exchange occurs between the ions of the clay (X+) and those of the electrolyte (Y+). The most common exchangeable cations are Na+, Ca2+, Mg2+, H+, K+, and NH4+.
Worall W. E., “Clays: their nature, origin and general properties”, MacLaren & sons, London (1968).
Utracki L. A., “Clay-containing polymeric nanocomposites”, Rapra Technology (2004).
Usuki A., Kawasumi M., Kojima Y., Okada A., Kurauchi T. and Kamigaito O., “Swelling behaviour of montmorillonite cation-exchanged for ω-amino acids by ε-caprolactam”, J. Mater. Res., 8, 1174-1178 (1993).
Jordan J. W., “Organophilic bentonites”, J. Phys. Colloid Chem., 53, 294-306 (1949).
Weiss A., “Organic derivatives of mica-type layer silicates”, Angew. Chem. internat. Edit., 2, 134-143 (1963).
Lan T., Kaviratna P. D. and Pinnavaia T. J., “Mechanism of clay tactoid exfoliation in epoxy-clay nanocomposites”, Chem. Mater., Vol. 7, No. 11, 2144-2150 (1995).
Wang Z. and Pinnavaia T. J., “Hybrid organic-inorganic nanocomposites: exfoliation of magadiite nanolayers in an elastomeric epoxy polymer”, Chem. Mater., 10, 1820-1826 (1998).
Plueddemann E. P., “Silane coupling agents, 2nd Ed.”, New York (1991).
Ogawa M. and Kuroda K., “Preparation of inorganic-organic nanocomposites through intercalation of organoammonium ions into layered silicates”, Bull. Chem. Soc., Jpn., 70, 2593-2618 (1997).
Southern Clay Product. Website: http://www.nanoclay.com
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