Rheological properties, clays

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. 

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. 

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%... 

Lepoittevin, B., Devalckenaere, M., Pantoustier, N., Alexandre, M., Kubies, D., Calberg, C., Jerome, R., and Dubois P. Poly (l-caprolactone)/clay nanocomposites prepared by melt intercalation Mechanical, thermal and rheological properties, Polymer (2002), 43,4017-4023. 

The clay component is the main factor controlling the rheological properties and the slip stability. Some part in this respect, hovewer, can also be played by the other very fine components. From the frit particles, water extracts alkalis which affect the colloidal and rheological properties of the slip. Since the extraction is gradual, the suspension is allowed to stand for a certain time before application to stabilize its properties. 

Fig. 4. Schematic diagram of the clay smear potential calculation. The CSP is calculated at a certain point at a fault from the thickness of individual clay source beds (/ ), and the distance from the source beds to that point (. ). For each clay bed that passed the calculation point, the thickness is squared and divided over the distance (h[ + Sj). The clay smears derived from all source beds that passed the calculation point are summed, both for the upthrown and downthrown side (CSP , CSP ). The highest of these is found to have the most predictive power and taken as the CSP. A calibration term (c) is included to cover rheological properties and stress dependencies of clay smear.

Several natural materials (waxes, clays, and asphalts) have rheological properties similar to synthetic products, but because they are not polymeric, are not considered true plastics. Certain proteins (casein, zein) are natural high polymers from which plastics are made (buttons and other small items), but they are of decreasing importance. 

Significant replacement of monovalent metal cations on layer silicate clay surfaces by protons can occur if the electrolyte concentration is very low. The long-term result, beyond hydrolytic exchange, is acidic decomposition of the clay structure in part, and release of structural AP or Mg + to solution. These multivalent cations may then readsorb onto exchange sites, influencing the rheological properties of clays in very dilute salts. Some of the anomalous behavior of Na -smectites suspended in... 

In the ceramic industry the rheology of clay suspensions plays a major role. Their colloidal properties are of especial significance in the process of slip-casting, in which a clay slurry is put in contact with a porous plaster mould, which sucks up the water to leave a solid form ready for firing, Here the suction provided by the porous mould in relation to the rate of flow of water through the clay matrix is important. The structure of the clay slurry, as determined by its degree of dispersion, has also to be controlled by suitable additives. 

Here we introduced a designation Go = -po> which corresponds to agreement about the sign of tension in the continuous mechanics. The last law is a law of flow with a limit tension of the shift (Bingham s body). This law as a limit case describes the rheology of clays, which are examined in experiments, Mitchell (1976). So, following this model we can receive the theory of the rheological properties of clays and this theory is in conformity with experimental results. 

In Reference 107, the effect of grafting of a polar group (MAH) onto LDPE chains and the chemical modification of clay particles with 2,6-diaminocaproic acid (L-lysine monohydrochloride) to produce nanocomposites with a matrix composed of a ternary blend of PEs (LDPE, LLDPE, and HDPE) was studied in detail. X-ray diffraction was used to determine the exfoliation degree of the clay. Morphological features were revealed by scanning electron microscopy and thermal analysis disclosed the thermal stability of the samples. Comparative analyses of the mechanical (under tension) and rheological properties of the nanocomposites were carried out as well. 

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