Clays rheology

Aside from easily derivable quantities like fault throw and stratigraphic bed thickness there are several other factors which affect the amount of clay smear, like the clay rheology during deformation, the... 

Polytrope. [Rheoxj Modified montmo-rillonite clay rheological additive, thickener for unsaturated polyester laminating resins. 

Water-Based Muds. About 85% of all drilling fluids are water-based systems. The types depend on the composition of the water phase (pH, ionic content, etc), viscosity builders (clays or polymers), and rheological control agents (deflocculants or dispersants (qv)). 

Inks. Refined kaolin is a common ingredient in a large variety of printing inks (qv). In addition to extending the more expensive polymers present, ka olin also contributes to improved color strength, limits the penetration of the ink into the paper, controls rheology, and improves adhesion. Kaolin for this appHcation must usually be as white as possible and free from oversize particles. Surface treated clays are used to improve compatibiHty with oil-based ink. Clays can also be an ingredient in the newer water-based or uv-cured inks. 

Dimensions. Most coUoids have aU three dimensions within the size range - 100 nm to 5 nm. If only two dimensions (fibriUar geometry) or one dimension (laminar geometry) exist in this range, unique properties of the high surface area portion of the material may stiU be observed and even dominate the overaU character of a system (21). The non-Newtonian rheological behavior of fibriUar and laminar clay suspensions, the reactivity of catalysts, and the critical magnetic properties of multifilamentary superconductors are examples of the numerous systems that are ultimately controUed by such coUoidal materials. 

For conventional wet processing of sheet steel, the porcelain enamel frit is ball-milled using clay, certain electrolytes, and water to form a stable suspension. This clay-supported slurry of small particles is called the sHp and has the consistency of a heavy cream. The ingredients of the mill batch are carefully controlled. The amount and purity of all materials in the mill, including the clay and water, affect the rheological character of the sHp as well as a number of the properties of the fined enamel such as chemical resistance, reflectance, gloss, color, and abrasion resistance. 

Fillers. Addition of fillers is not common in polychloroprene latex formulations. Fillers are used to reduce cost and control rheology, solids content and modulus. However, cohesion and adhesion are reduced. Calcium carbonate, clay and silica are some of the fillers than can be added. Alumina trihydrate is often used when resistance to degradation by flame is important. 

Interface and its Rheological Implications, Clay Minerals Society, Boulder, CO, USA (1992). 

A biopolymer produced by a particular strain of bacteria is becoming widely used as a substitute for clay in low-solids muds. Since the polymer is attacked readily by bacteria, a bactericide such as paraformaldehyde or a chlorinated phenol also must be used with the biopolymer. The system has more stable properties than the extended bentonite system, because biopolymer exhibits good rheological properties in its own right, and has a better tolerance to salt and calcium. The system can be formulated to include salt, such as potassium chloride. Such a system, however, would then be classed as a nondispersed inhibitive fluid. 

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. 

PP is probably the most thoroughly investigated system in the nanocomposite field next to nylon [127-132]. In most of the cases isotactic/syndiotactic-PP-based nanocomposites have been prepared with various clays using maleic anhydride as the compatibilizer. Sometimes maleic anhydride-grafted PP has also been used [127]. Nanocomposites have shown dramatic improvement over the pristine polymer in mechanical, rheological, thermal, and barrier properties [132-138]. Crystallization [139,140], thermodynamic behavior, and kinetic study [141] have also been done. 

Clay hllers were surface modihed with TMPTA or triethoxyvinyl silane (TEVS) followed by EB irradiation by Ray and Bhowmick [394]. Both the untreated and treated fillers were incorporated in an ethylene-octene copolymer. Mechanical, dynamic mechanical, and rheological properties of the EB-cured unfilled and filled composites were studied and a significant improvement in tensile strength, elongation at break, modulus, and tear strength was observed in the case of surface-treated clay-filled vulcanizates. Dynamic mechanical studies conducted on these systems support the above findings. 

D. Dino and J. Thompson. Organophilic clay additives and oil well drilling fluids with less temperature dependent rheological properties containing said additives. Patent EP 1138740A, 2001. 

Of even more economic importance is the rheological impact of the addition of KC1 to conventional water-base drilling fluids. KC1 causes undesirable increases in both yield point and gel strength that can only be eliminated by chemical disperants or by dilution with fresh water. Dilution in turn requires more KC1 for clay inhibition, and the cycle continues with mud costs escalating exponentially. 

This behavior can be explained with the help of the classical rheological theory of suspension of conventional filler reinforced systems. According to this theory [32], rotation of the filler is possible when the volume fraction of clay 4>fflier < 4 critical — (aspect ratiop1. All PBSNCs studied here follow this relation except PBSNC4 (MMT = 3.6 wt%), in which 4)mier (aspect ratio) 1. For this reason, in... 

Rheological modifiers (LD, DW, ADW, HC, FC) Improve flow properties of product, enhance consumer appeal, assist manufacturing Rheological behavior Clays Polymers Sodium silicate Sodium sulfate Solvents 0.5-2% 0.5-2% 3-15% 0-5%... 

There are many other forms of clay including synthetic clays such as laponite, a synthetic hectorite. Suitable tuning of the properties of these systems can produce similar structures. These systems have the advantage of small particle size and a relatively improved level of particle monodispersity over their naturally occurring counterparts and are being increasingly used as rheology modifiers. 

N. Guven and R. M. Pollastro (eds.), Clay-Water Interface and Its Rheological Implications, Clay Minerals Society Workshop Lectures, Vol. 4 (The Clay Minerals Society, Boulder, CO, 1992). 

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