Silicate epoxy matrix

Other nanocomposite CNT electrodes have been reported by mixing CNTs with granular Teflon [48], chistosan [110], polystyrene [111], polysulfone [112] and epoxy [103, 113] or by incorporating them into a silicate gel matrix [13, 114]. 

In a study of dental silicate cements, Kent, Fletcher Wilson (1970) used electron probe analysis to study the fully set material. Their method of sample preparation varied slightly from the general one described above, in that they embedded their set cement in epoxy resin, polished the surface to flatness, and then coated it with a 2-nm carbon layer to provide electrical conductivity. They analysed the various areas of the cement for calcium, silicon, aluminium and phosphorus, and found that the cement comprised a matrix containing phosphorus, aluminium and calcium, but not silicon. The aluminosilicate glass was assumed to develop into a gel which was relatively depleted in calcium. 

As matrix polymer, an epoxy polymer based on 3,4-epoxycyclohexyl-methyl-3,4-epoxycyclohexane carboxylate (epoxy monomer), cured by hexahydro-4-methylphthalic anhydride at a molar ratio of 0.87-1.0 was used. To this mixture a nanofiller, MMT (Cloisite 30B) was added. Before this the nanofiller was mixed with denatured ethanol for removal of any excess of surfactants from the silicate platelets surface. This mixture was then centrifuged at 5,000 rpm for 10 min prior to the decanting of the ethanol. After Cloisite SOB addition the mixture was stirred in a mixer at... 

In-situ intercalative polymerization of layered silicates is perhaps the best example of reactive molding of nanocomposites today. In-situ interactive polymerization of layered silicates, which was discussed above, can be achieved either with thermosetting matrices, such as polyurethane and epoxy, or with thermoplastic systems, such as nylon-6 [4, 23]. A general requirement for reactive molding of nanocomposites is that the particulate phase of a PNC is compatible with the monomer phase of the reactive molding system, which acts as a polymerizable solvent This makes it possible to achieve and maintain a fine dispersion of the particulate phase in the monomer during matrix consolidation, resulting in excellent particle distribution in the final PNC. Above, it was noted that the hydroxylated surface of cellulose makes it reactive to isocyanate. Cellulose whiskers may therefore represent the ideal particulate phase for a nano-RIM process. For this to be achieved, the whisker-polyurethane system needs to be better characterized, so that the RIM process can be adapted to fabrication of cellulose whisker PNCs. 

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