Rheology stabilizers

Perhaps the best rheological stability criterion is the volume occupied by the sediment per unit volume of original dispersion. A flocculated dispersion settles rapidly to a high sediment volume, while a deflocculated one settles slowly to a low volume, as shown in Figure 8. Of course, the ultimate volume depends on the concentration of the dispersion and in order to give a criterion of more fundamental interest the concept of relative sediment volume RSV may... 

Figure H3.1.10 The temperature stability of four emulsions. Emulsions A and B show a high dependence of rheological stability on temperature. Emulsions C and D have rheological properties that are relatively independent of temperature.

Radiation radiation, depending on wavelength and dose, has been shown to have a variety of effects, including increased gelatinization temperature, improved stability and reduced viscosity, swelling power and enzyme susceptibility. Radiation has also been used to promote chemical modification. Marquette et al.118 have a patent for microwaving starch to improve rheological stability and hot water dispersibility. They... 

Before we discuss the applications of US-based detection techniques, we should emphasize the difference between the measured data and the desired output parameters. In ultrasound spectrometry, the measured data can be the attenuation coefficient, the sound speed and the acoustic impedance. However, the researcher is rarely interested in these measured properties, but rather on elastic moduli of solid samples particle size distributions or rheological properties of heterogeneous samples and concentrations, rheology, stability and chemical reactivity of liquids (particularly emulsions). 

The rigidity and strength of networks prepared with cetostearyl alcohol and alkyltrimethyl-ammonium bromides (Cj2-Cjg) increase as the alkyl chain length increases. The rheological stability of ternary systems is markedly dependent on the alcohol chain length networks prepared with ionic or nonionic surfactants and pure cetyl or pure stearyl alcohol are weaker than those prepared with cetostearyl alcohol. In particular, emulsions prepared with stearyl alcohol are mobile and eventually separate. 

Gamble) phytic acid, rheology stabilizing agent and physical stability... 

Rheology, Less Stringy Rheology, Stability Efficiency... 

A strong semi-quantitative link has been made between rheology/stability and drop size and between drop size and processing conditions. A fundamental approach therefore requires a study of toth links. The first is outside the scope of these notes, but the literature contains a great deal of useful information. Some comments on the second are made below. 

Precipitated silicas and silica gels are used in toothpastes as abrasives and as rheology stabilizer. The hardness, the structure and particle size distribution of the silicas are the properties which control the abrasiveness and the rheology of the toothpaste. For transparent toothpastes also fumed silicas are in use. 

Fig. 18.4 Rheological stability of PANl solutions in NMP and DMPU at a constant shear rate of 0.75 s (From Ref. 57.)...

Greases Mechanical and rheological behavior and its persistence Consistency and viscosity Mechanical stability Oxidation resistance... 

Many properties of colloidal suspensions, such as their stability, rheology, and phase behaviour, are closely related to the interactions between the suspended particles. The background of the most important contributing factors to these interactions is discussed in this section. 

Commercial Stabilizers. There is a great variety of commercial formulations utilizing the mixture of the alkaU and alkaline-earth metal salts and soaps. In many cases, products are custom formulated to meet the needs of a particular appHcation or customer. The acidic ligands used ia these products vary widely and have dramatic effects on the physical properties of the PVC formulations. The choice of ligands can affect the heat stabiHty, rheology, lubricity, plate-out tendency, clarity, heat sealabiHty, and electrical and mechanical properties of the final products. No single representative formulation can cover the variety of PVC appHcations where these stabilizers are used. 

Many different combinations of surfactant and protective coUoid are used in emulsion polymerizations of vinyl acetate as stabilizers. The properties of the emulsion and the polymeric film depend to a large extent on the identity and quantity of the stabilizers. The choice of stabilizer affects the mean and distribution of particle size which affects the rheology and film formation. The stabilizer system also impacts the stabiUty of the emulsion to mechanical shear, temperature change, and compounding. Characteristics of the coalesced resin affected by the stabilizer include tack, smoothness, opacity, water resistance, and film strength (41,42). 

Because of this interaction, PVP has found appHcation in surfactant formulations, where it functions as a steric stabilizer for example to generate uniform particle-size polystyrene emulsions (110—112). In a variety of formulations, a surfactant s abiHty to emulsify is augmented by PVP s abiHty to stabilize coUoids stericaHy and to control rheology. 

Sources of Toxicity. There are three contributing mechanisms of toxicity in drilling fluids, chemistry of mud mixing and treatment, storage/disposal practices, and drilled rock. The first group conventionally has been known the best because it includes products deliberately added to the system to build and maintain the rheology and stability of drilling fluids. 

In this approach the reviews concerned the rheology involving the linear viscoelastic behavior of plastics and how such behavior is affected by temperature. Next is to extend this knowledge to the complex behavior of crystalline plastics, and finally illustrate how experimental data were applied to a practical example of the long-time mechanical stability. 

Ether carboxylates are used not only in powdered detergents but in liquid laundry detergents for their hard water stability, lime soap dispersibility, and electrolyte stability they improve the suspension stability and rheology of the electrolyte builder [130,131]. Formulations based particularly on lauryl ether carboxylate + 4.5 EO combined with fatty acid salt and other anionic surfactants are described [132], sometimes in combination with quaternary compounds as softeners [133,163]. Ether carboxylates show improved cleaning properties as suds-controlling agents in formulations with ethoxylated alkylphenol or fatty alcohol, alkyl phosphate esters or alkoxylate phosphate esters, and water-soluble builders [134]. 

In a current rheological study [296], the galactoxyloglucan from Hymenia courbaril was mixed with starch containing 66% amylose and with waxy corn starch (amylopectin). The gel mixtures showed, under static rheological conditions, an increase in paste viscosity compared to those of the polysaccharides alone. Dynamic rheometry indicated that the interactions resulted in increased thermal stability of the gel formed in comparison to that of the starch alone. 

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