Concentrated suspensions, temperature

Styrene-based polymer supports are produced by o/w suspension polymerization of styrene and divinylbenzene. Suspension polymerization is usually carried out by using a monomer-soluble initiator such as benzoperoxide (BPO) or 2,2-azo-bis-isobutylnitrile (AIBN) at a temperature of 55-85°C (19). A relatively high initiator concentration of 1-5% (w/w) based on the monomer is used. The time required for complete monomer conversion must be determined by preliminary experiments and is usually between 5 and 20 h, depending on the initiator concentration, the temperature, and the exact composition of the monomer mixture (11-18). 

This is suitable for the formulations in which the percentage of solid ingredients, suspended in liquid is to be increased. The advantage of density difference between the molten medium and suspended particles is used in this process. The concentration of heavier particles is increased in the lower part of the casing either by natural sedimentation or by forced sedimentation caused by vibrating the whole casting assembly. The sedimentation process is controlled by a number of parameters such as particle size of solid suspension, temperature of melt, period of sedimentation, viscosity of melt, concentration of solid ingredients and column of melt etc. 

B.K. Aral and D.M. Kalyon, Effects of Temperature and Surface Roughness on Time-Dependent Development of Wall Slip in Steady Torsional Flow of Concentrated Suspensions, J. Rheol., 38(4) 957-972 (1994). 

Lipstick and lip balms are usually concentrated suspensions of solid oils in a liquid oil, or in a mixture of liquid oils. The dispersed phase, about 60 mass%, comprises oils and/or wax that are solid at room temperature. The continuous phase, about 40 mass%, comprises an oil, or mixture of oils, that is liquid at room temperature. These products are formulated at relatively high temperature, where they are liquid, and are then cooled to allow a significant yield stress to develop. Lipsticks and lip balms contain a variety of waxes, oils, pigments, and emollients, including ... 

In these experiments the DDT would almost certainly be in the supercooled liquid state, which persists for a surprisingly long time in much more concentrated suspensions than those used. The vapor pressures quoted from Balson (5) and the later, higher figures of Dickinson (10) refer to crystalline DDT. The supercooled liquid would be expected (since the solubility of the solid in best solvents corresponds to about one-ninth on a mole fraction basis) to have about nine times the vapor pressure at room temperature of the crystals. There is little discrepancy left. In view of the facts that all measurements had to be made at less than 1 p.p.m. concentration, that DDT loss had to be obtained by difference, and that adsorption on vessel walls is difficult to allow for, this work leaves me with no anxiety for the validity of classical physicochemical theory. Distillation from supercooled droplets on a glass plate to growing crystals has been demonstrated by Feichtmeir (12). 

A new apparatus was developed for continuous extraction of contaminated soil material for high pressure (25 MPa) and high temperature (663 K) operating conditions. The extraction of hydrocarbon contaminants from long weathered and highly contaminated soil material could be realised with supercritical water under parallel flow. Within a residence time of only 28 s suspensions of less than 0.75 wt% soil in water could be cleaned (> 90 %). For a concentration of 1 wt% soil in water 43 s were needed to achieve a clean-up result of 98.3 %. The continuous extraction process can be carried out multistage. Then higher concentrated suspensions (2-4 wt%) can be also cleaned by supercritical water extraction. 

The EMR spectra of the ferrofluid demonstrate a broad line with peak-to-peak width depending on concentration and temperature (Figure 1). The increasing of line width with concentration increasing and temperature decreasing occurs due to dipole-dipole interaction and local ME influence. In diluted suspension at room temperature where dipole-dipole interaction can be neglected the peak-to-peak width is equal to 680 G. It is typical for resonance of microparticles with a broad size distribution of the particles [11-13]. Center of this line at room temperature locates in the ME near 3400 G (g-factor = 2.25). With temperature decreasing the center shifts to lower MFs. 

Tests were conducted with a rotational viscometer with 30, 40, and 60 lb HPG/1000 gal fluids containing neutrally buoyant 60-100 mesh styrene divinylbenzene beads at concentrations up to 12 lb/gal and temperatures up to 65.5 °C. Data were gathered only at three shear rates 5, 170, and 1000 s-1. Their modified Eiler s equation was based on correlating relative viscosity as a function of clean fluid n values, solids concentration, and fracture shear rate. The gel concentration and temperature effects were incorporated into n. Figure 1 depicts the effect of polymer concentration on the relative viscosity of suspension at a shear rate of 170 s-1 and 23.9 °C. It can be seen that the lower polymer concentration has the greater viscosity ratio than the higher concentrations and that the difference between these increases with volume fraction solids. 

The equilibrium solute concentration (c ) is usually influenced by the suspension temperature (T) through the solubility-temperature relationship. In a nonisothermal batch crystallizer (e.g., batch cooling crystallizer or when the heat of crystallization is significant), the suspension temperature may change with time. In this case, an energy balance is needed to determine the suspension temperature (and the associated c ) as a function of time. 

Aral, B.K. and D.M. Kalyon, Ejfects of temperature arul surface roughness on time-dependent development of wall slip in torsional flow of concentrated suspensions. Journal of Rheology, 1994. 38 p. 957-972... 

Two phenomena are responsible for flux decline during membrane operation with real fluids [27]. One is related to polarization phenomena (concentration and temperature polarization), which normally are reversible processes. Thus, at a finite time, when steady-state conditions have been attained, the flux stabilizes at a value always less than the original one. Membrane fouling is the second phenomenon responsible for flux decline. It consists of the deposition of retained particles, colloids, anulsions, suspensions, macromolecules, salts, etc., on/in the membrane. Fouling always results in a continuous (ir)reversible decrease of membrane flux with time and constitutes one of the major problem to be managed during filtration plant operation. 

Liquid continuous phase. Gas-in-liquid dispersions are the foams or the boiling liquids (Prud homme and Khan 1996, Exerova and Kruglyakov 1998). Liquid-in-liquid dispersions are usually called emulsions. The emulsions exist at room temperature when one of the liquids is immiscible or mutually immiscible in the other, e.g. water, hydrocarbon and fluorocarbon oils and liquid metals (Hg and Ga). Many raw materials and products in food and petroleum industries exist in the form of oil-in-water or water-in-oil emulsions (Shinoda and Friberg 1986, Sjoblom 1996, Binks 1998). The solid-in-liquid dispersions are termed suspensions or sols. The pastes, paints, dyes, some glues and gels are highly concentrated suspensions (Schramm 1996). 

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