Particle size reducing

Dispersants (qv) have been added to the pulper to maintain stickies in a colloidal state. The small particle size reduces the problems stickies cause on the paper machine and in paper products. Among the chemicals that have been used are fatty alcohol ethoxylates, alkylphenol ethoxylates, lignosulfonates, and naphthalene sulfonates (18). 

Microemulsion and miniemulsion polymerization processes differ from emulsion polymerization in that the particle sizes are smaller (10-30 and 30-100 nm respectively vs 50-300 ran)77 and there is no discrete monomer droplet phase. All monomer is in solution or in the particle phase. Initiation usually takes place by the same process as conventional emulsion polymerization. As particle sizes reduce, the probability of particle entry is lowered and so is the probability of radical-radical termination. This knowledge has been used to advantage in designing living polymerizations based on reversible chain transfer (e.g. RAFT, Section 9.5.2)." 2... 

Manufacturing processes afford azo pigments with, for instance, certain defined physical forms. Thermal treatment usually increases the particle size, reduces the tinctorial strength, and may improve the hiding power of a pigment. Reversal of... 

Effect of particle size. Reducing the particle size in the bed will reduce the size of the pores and the waists, and will increase the entry suction potential of the waists. This increase means that the percentage variation in suction potentials with depth is reduced, and the moisture distribution is more uniform with small particles. 

As measured, the Hs term means that a smaller particle size reduces the distance between particles, and thus the spreading due to diffusion of sample molecules is minimized. From Equations 5.18 and 5.19, a decrease in H value is achieved by increasing the diffusion speed (elevating the column temperature,... 

Diluted binders are preferred because they facilitate finer atomization of the binder solution, provide control of the particle size, reduce friability and increase the bulk density, even though the tackiness or binding strength may suffer (8,68,78,82,82,97). 

The mean particle size is a function of the pre-expansion temperature the particle size reduces with lower pre-expansion temperatures.The closer the saturation temperature is to the melting point of the substance, the smaller are the formed particles. The smallest particles were obtained at high pressure and low temperature, which could have been expected, owing to the higher solubility of CO2 in the melted substances and the resulting higher level of supersaturation during the expansion. 

The coarse, nonpigmentary cmdes are particle size reduced by a variety of processes to obtain pigmentary CPC. Since CPCs are utilized in a variety of industries and a host of applications, the specific property requirements vary widely. A large number of special-purpose types are commercially available designed to provide optimal properties for specific applications. 

Indanthrone. Pigment Blue 60 [81-77-6] is synthesized by oxidative dimerization of 2-aminoanthraquinone in the presence of a strong base, and then particle size reduced by precipitation from very strong sulfuric acid or by milling. The very red-shade blue pigment shows outstanding weatherfastness in full shade as well as in light white reductions. It is used primarily in metallized automotive finishes where it is sometimes more weatherfast than copper phthalocyanine blue. 

All three properties of carbon black affect hardness in natural rubber compounds (Fig. 18). Larger particle size reduces hardness higher structure increases hardness and increased surface area reduces hardness. Quite the contrary in SBR (Fig. 19), only structure is significant in regard to hardness. As DBP increases, hardness increases. 

Smaller particle size reduces secondary reactions... 

Elutriation—the selective removal of fines by entrainment—has been studied by several workers (K25, L6, M23, 08, T7, W2). Most of this work has been reviewed by Kunii and Levenspiel (K24) and Leva and Wen (in D5). However, Merrick and Highley (M13) point out that early correlations for elutriation rate constant are inaccurate for very fine particles, since they assume m, proportional. od% (rather than toc/p) and hence predict that the elutriation rate constant reduces to zero as the particle size reduces to zero. Thus, care must be taken when such empirical equations are applied to a fluid bed containing fine particles. 

The rate constant k is sensitive to temperature and, in principle, should be associated with the temperature of the catalyst particle. However, the high thermal conductivity of liquids (in comparison with that for gases) and the small particle size reduce the temperature difference between liquid and particle. Hence external temperature differences are not normally important in slurry reactors. 

Stability can be reached if the density of the dispersed phase exactly matches that of the continuous phase. This is difficult to achieve in practice as the volumic expansion coefficients are different for oil and water. Density matching accordingly holds only at one temperature. Decreasing the particle size reduces the separation rate but does not stop it. Moreover, particle size reduction commonly leads to a viscosity increase, and even to gelling. Increasing the viscosity contributes to separation reduction but it is not very easy to achieve in practice. 

Uses Gloss aid, color enhancer, pigment grind vise, improver, particle size reducer, antisettling agent, tint str. improver in cosmetic pigment disps., makeup moisturizer, color enhancer in lip prods. 

Arsenic trioxide Copper acetate (ic) particle size reducer, make up Castor oil benzoate... 

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