Silicate composites interfacial area

Figure 11.1. The first type is conventional composites, where non-swollen clay tactoids with layers are dispersed simply as a segregated phase in a polymer matrix, which results in poor mechanical properties of the composite material. The second type is intercalated polymer-clay nanocomposites, which are well-ordered multilayered structures formed by the insertion of polymer chains into the gallery space between parallel individual clay layers. Although the layer spacing of clay increases, there are still attractive forces between the silicate layers to stack the layers with uniform spacing. The last type is exfoliated polymer-clay nanocomposites, in which the clays are well dispersed in the polymer matrix. Compared with the intercalated polymer-clay nanocomposites, the layer spacing in the exfoliated polymer-clay nanocomposites increases to the point that there are no longer sufficient attractions between the silicate layers to maintain a uniform layer spacing. The last two hybrid structures are nanocomposites and the exfoliated polymer-clay nanocomposites are especially desirable for improved properties because of the homogeneous dispersion of clay and huge interfacial area between the polymer and clay.

The ineorporation of a few weight pereent of modified layered silieates whieh are properly dispersed in the mbber matrix ean result in very high surface areas for rubber-elay interactions, as compared to the conventional rubber-filler composites. According to the strength of the interfacial interactions between rubber matrix and layered silicate four type of rubber-clay composites can be produced ... 

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