Second phase particles silicates

The second significant independent variable that layered silicates provide to increase thermal stability of the polymer in polymer-clay nanocomposites is an increase of the melt viscosity. If thermal degradation of the polymer is diffusion controlled, an increase in viscosity of the polymer melt will slow the mass loss associated with gas escaping from the composite during TGA evaluations. The increase in viscosity of dispersions is a function of the surface area of the dispersed phase. For example, water-based dispersions will increase in viscosity as the particle size of the dispersed phase decreases at constant total volume of the dispersed phase. This is the result of an increase in total surface area of the dispersed phase. Particle-particle interaction has increased as a function of increased total particle surface area. The surface area [17] of fully exfoliated montmorillonite is approximately 750 m /g. This enormous number results in a significant increase in polymer-montmorillonite melt viscosity at low concentration of montmorillonite and low shear rates [18]... 

In the case of the 90% MgO class refractory, the brick contained 95.5% MgO, 2.7% CaO, and 1.4% Si02. This implies that the native silicate in the brick is dicalcium silicate (2CaO Si02)—a very refractory second phase providing for a part of the bonding in a product where direct sintered bonds between adjacent MgO aggregate particles predominate. In service, a transient period... 

On the other hand, the role of both, binders for stabilizing structure and the graphite for increasing porosity was analysed. A literature search [18] showed that the most common binders for these reactions were the bentonite and natural silicates (2-4% w/w) with 1,5-3 Kg/mm in order to provide some cohesion and increase the mechanical strength to the zinc titanite and zinc ferrite particles. In the second step, several supported sorbents (10% of active phase) have been prepared and characterised. 

Cement is a binder that sets and hardens by itself or binds other materials together. The most widely known application of cements is in construction a second one is the area of bone cements. Cements used in construction are characterized as hydraulic or nonhydraulic and mostly for the production of mortars and concrete. Hydraulic cements set and harden after combining with water. Most construction cements are hydraulic and based on Portland cement, which consists of calcium silicates (at least 2/3 by weight). Nonhydraulic cements include the use of nonhydraulic materials such as lime and gypsum plasters. Bone cements and bone cement composites refer to compounds that have a polymer matrix with a dispersed phase of particles. For instance, polymethylmethacrylate (PMMA) is reinforced with barium sulphate crystals (for radio-opacity) or with hydroxyapatite... 

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). 

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