Layered silicates preparation

Three main types of composites can be formed when the layered clay is incorporated with a polymer, as shown in Figure 2 (Alexandre and Dubois, 2000). Types of composites formed mostly depend on the nature of the components used (layered silicate, organic cation and polymer matrix) and the method of preparation. 

Alexandre, M. and Dubois, P. 2000. Polymer-layered silicate nano-composites preparation, properties and uses of a new class of materials. Materials Science and Engineering 28 1- 63. 

Homminga, D., Goderis, B., Hoffman, S., Reynaers, H. and Groeninckx, G. 2005. Influence of shear flow on the preparation of polymer layered silicate nanocomposites. Polymer 46 9941-9954. 

Ray, S.S. and Okamoto, M. 2003. Polymer/layered silicate nanocomposite a review from preparation to processing. Progress in Polymer Science 28 1539-1641. 

This mbber is very tacky in nature and contains acrylic group, which makes it polar in nature. Nanocomposites have been prepared based on this elastomer with a wide range of nanohllers. Layered silicates [53-55] have been used for this preparation. Sol-gel method [56,57], in situ polymerization [58], and nanocomposites based on different clays like bentonite [59] and mica [60] have been described. The mechanical, rheological, and morphological behaviors have been investigated thoroughly. 

Since the possibility of direct melt intercalation was first demonstrated [11], melt intercalation has become a method of preparation of the intercalated polymer/ layered silicate nanocomposites (PLSNCs). This process involves annealing, statically or under shear, a mixture of the polymer and organically modified layered fillers (OMLFs) above the softening point of the polymer. During annealing, the polymer chains diffused from the bulk polymer melt into the nano-galleries between the layered fillers. 

K. Okamoto and M. Okamoto also investigated the biodegradability of neat PBS before and after nanocomposite preparation with three different types of OMLF. They used alkylammonium or alkylphosphonium salts for the modification of pristine layered silicates, and these surfactants are toxic for microorganisms [56]. 

On the other hand, Bhattacharya et al. have reported the plasticization effect of organically modified layered silicates on dynamic mechanical properties [13]. In this work, nanocomposites of SBR have been prepared using various nanofillers like modified and unmodified montmorillonite, SP, hectorite etc. It has been observed that the Tg shifts to lower temperature in all the nanocomposites, except for systems from hectorite and NA. This is due to the fact that clay layers form capillaries parallel to each other as they become oriented in a particular direction. Due to wall slippage of the unattached polymer through these capillaries, the Tg is lowered, which could be even more in the absence of organo-modifiers [13]. A similar type of plasticization effect is also noted in the case of the low... 

During the past decade, rubber-layered silicate nanocomposites have been extensively studied for a variety of applications and in this review the preparation and characterization of such layered silicate-rubber composites is discussed. However, use of another type of clay, called anionic clay or LDH, in the rubber matrix is rather uncommon. In this section, rubber-LDH nanocomposites are described, including the synthesis and characterization of OLDH, preparation of rubber-LDH nanocomposites, and their special properties [94, 95]. 

We have presented several examples of the successful preparation of rubber nanocomposites with layered silicate as the inorganic phase. This review explores the idea that the designing and compounding are key factors in obtaining the... 

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