Montmorillonite clay plates dispersion

Figure 10.5 Schematic illustration of the use of wide angle x-ray diffraction for studying the dispersion of montmorillonite clay plates, (a) sodium form, (b) quaternary ammonium form and (c) quaternary ammonium form dispersed in polymer...

Moleculady mixed composites of montmorillonite clay and polyimide which have a higher resistance to gas permeation and a lower coefficient of thermal expansion than ordinary polyimides have been produced (60). These polyimide hybrids were synthesized using montmorillonite intercalated with the ammonium salt of dodecylamine. When polymerized in the presence of dimethyl acetamide and polyamic acid, the resulting dispersion was cast onto glass plates and cured. The cured films were as transparent as polyimide. 

Nanofillers. Nanofillers are extremely fine particles, under a micron in size. The most successful ones have been made by intercalating quaternary ammonium surfactants between the layers of montmorillonite clay, followed by fluid polymer, to exfoliate them down to 1-nm platelets with aspect ratio of 1000/1. When these are dispersed in nylon at low concentrations of 2 to 10 percent, the tremendous numbers of plate-like particles can produce easy processing, high modulus and strength, heat deflection temperature, trans-... 

The Li ions were introduced in two different ways either before or after Zr intercalation. The montmorillonite (Weston L-Eccagun) was first exchanged with NaCl (IN) and washed. Two montmorillonites with reduced charge were prepared following the Brindley and Ertem method (13). Part of the Na+ montmorillonite was first saturated with LiCl (IN) and washed. The Li+ clay thus obtained and Na+ clay suspension were stirred for 24 hours at 25°C and dried on glass plate. The films were then heated at 220°C for 24 h in order to allow Li diffusion in the clay structure. Two different Li concentrations (F=0.4 and F=0.6) were used. The Na Li+ modified montmorillonite were dispersed in water acetone solution (1/1). The ZrOCla, 8H2O solution was added to the Na+Li+ montmorillonite (0.02g.l l Zr/Clay=5.CEC). The suspension was stirred with NaOH solution (0.1 N) up to a OH/Zr ratio of 0.5. The final pH of the suspension was 1.85. After two hours of reaction at 40°C the Zr pillared clay was washed up to constant conductivity of the solution, freeze-dried and calcined at different temperatures up to 700°C (Eni-02 and EIII-03). 

Example 5.4 The clay minerals are composed [46, 89] of sheets of tetrahedrally coordinated silica and sheets of octahedrally coordinated alumina or magnesia. These sheets occur stacked upon one another forming plate-like layers or particles. Montmorillonite, for example, clay occurs as relatively broad, thin platelets, typically about 0.3 pm across and about 2 nm thick. When dispersed in aqueous solutions of near-neutral pH to alkaline pH, the particles carry a net negative... 

Nano-plates are generally naturally occurring layered materials such as layered silicates (montmorillonite plates, a type of clay) which is dispersed within polymers for nanocomposite formation (Hackman and Hollaway, 2006 Tran et al. (2006) initially man-made materials such as silicate acids were used (Wang et al., 1996). The objective in a nanocomposite produced from plate-like fillers is to disperse the latter in a polymer to take advantage of... 

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