Montmorillonite Polymer-clay nanocomposites

Figure 16.24 shows the schematic representation of dispersed clay particles in a polymer matrix. Conventionally dispersed clay has aggregated layers in face-to-face form. Intercalated clay composites have one or more layers of polymer inserted into the clay host gallery. Exfoliated polymer/clay nanocomposites have low clay content (lower than intercalated clay composites which have clay content -50%). It was found that 1 wt% exfoliated clay such as hectorite, montmorillonite, or fluorohectorite increases the tensile modulus of epoxy resin by 50-65%. ... 

Polymer clay nanocomposites have, for some time now, been the subject of extensive research into improving the properties of various matrices and clay types. It has been shown repeatedly that with the addition of organically modified clay to a polymer matrix, either in-situ (1) or by melt compounding (2), exfoliation of the clay platelets leads to vast improvements in fire retardation (2), gas barrier (4) and mechanical properties (5, 6) of nanocomposite materials, without significant increases in density or brittleness (7). There have been some studies on the effect of clay modification and melt processing conditions on the exfoliation in these nanocomposites as well as various studies focusing on their crystallisation behaviour (7-10). Polyamide-6 (PA-6)/montmorillonite (MMT) nanocomposites are the most widely studied polymer/clay system, however a systematic study relating the structure of the clay modification cation to the properties of the composite has yet to be reported. 

Polymer-clay nanocomposite materials can be prepared by intercalation of NVK into montmorillonite followed by the photoinitiated polymerization with a triarylsulfonium salt. ... 

Voorn DJ, Ming W, Van Herk AM (2006) Polymer-clay nanocomposite latex particles by inverse Pickering emulsion polymerization stabilized with hydrophobic montmorillonite platelets. Macromolecules 39(6) 2137-2143... 

Figure 28 shows the relationships between the amount of inorganics in the clay and the gas permeability coefficient. The gas permeabiUty coefficient decreased as the amount of added clay increased. The gas barrier performance of PPCN-5 increased by 1.7 times. It has been reported that the barrier performance of the nylon-clay nanocomposites and polymer-clay nanocomposites was improved. This barrier effect is explained as being attributed to the geometrical detour effect of the dispersed nanosized silicates. The barrier effect of PPCN, however, was smaller than that of the nylon-clay nanocomposites. hi the case of the nylon-clay hybrid, the addition of 1.8 wt % of mont-morillonite caused its hydrogen permeability to decrease to 70%. In the case of PPCN, about 3 wt % of montmorillonite must be added to obtain the same... 

Sodium montmorillonite (Na-MMT) was originally modified with pro-tonated amino acids with different numbers of carbon atoms and subsequently swollen with e-caprolactam. Then it underwent polymerization to produce nylon-6 polymer-clay nanocomposite [18]. Later, this technique was also extended to manufacture other thermoplactics. One advantage of this in-situ polymerization technique is the tethering effect, which enables the organic chemical such as 12-aminododecanoic acid (ADA) situated at the surface of the nanoclays to link with nylon-6 polymer chains during polymerization. 

Most of the research on polymer/clay nanocomposites reported in the literature has been focused on platelet-like clays, usually smectite clays such as montmorillonite (MMT) [1-4]. Considerably less work has been carried out on other forms of clays (Figure 12.1). 

The field of clay-polymer nanocomposite technology is attracting a great amount of attention (169). Among clay minerals, the 2 1 natural clay mineral montmorillonite has been used for clay nanocomposite applications. The structure of nanocomposites, the dynamics of confined polymer clay nanocomposites using NMR and computer simulations, rheology of clay nanocomposites have been... 

In this chapter, we shall deal mainly with montmorillonite (MMT) clay and with organo-clays and polymer/clay nanocomposites containing polystyrene (PS) as the matrix and incorporating MMT as the clay. 

Plastic additives based on layered aluminum silicate, montmorillonite clay, have drawn significant attention in the polymer and plastic community in the past 10 years. This article will focus on the general chemistry of polymer-clay nanocomposites and their applications as flame retardant additives. 

Therefore, polymer/clay nanocomposites can be deflned as a new class of composites with polymer matrices in which the dispersed phase is the silicate constituted by particles that have at least one of the dimensions at nanometer level. One of the components is the matrix, in which the particles of the second material are dispersed. The most used mineral particles in these nanocomposites are smectitic clays (montmorillonite, saponite, and hectorite), having their particles lamellae morphology with sides at micrometer level and thickness around one nanometer (Alexandre and Dubois, 2000 Esteves, Barros-Timmons, and Trindade, 2004). 

It is well-known that montmorillonite (MMT) clay is the most used clay in polymer/ clay nanocomposite foams. Hence, it is suitable to present the effect of adding montmorillonite clay in the preparation of polymer nanocomposite foams and its effect... 

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