Selection of dispersants

In principle, the selection of dispersion equipment for a given purpose is very simple. The obvious choice is the one that will give the required degree of dispersion most economically. In practice it is not so easy. Availability of equipment, the nature of the raw materials, mill-base formulation, batch size, product type and the time available all influence the decision of which machine to use. 

Instead of the absorption of chiral modifiers on metal surfaces, a new method using a slightly different approach attaches chiral moieties directly to metal surfaces through chemical bonds. Chiral silyl ethers have been attached to Pd surface atoms these new catalysts have the form (Pd)s=Si-0-R(,< orS) 42 Their synthesis arose from studies of the effects of siliconation on the catalytic activities and selectivities of dispersed, supported Pd and Pt.43-47 The results from... 

U. Khan, A. O Neill, H. Porwal, P. May, K. Nawaz, J.N. Coleman, Size selection of dispersed, exfoliated graphene flakes by controlled centrifugation, Carbon, 50 (2011) 470-475. 

A discussion on the selection of dispersing agents and the optimum concentrations to be used has been published [92], For a fuller discussion of dispersion, readers are referred to Nelson [93] and Conley [94],... 

Studart, A.R. etal.. Selection of dispersants for high-alumina zero-cement refractory castables, 7. Eur. Ceram. Soc., 23, 997, 2003. 

Relative permeability (cont./dispersed phase) Fig. 7.9 Selectivity of a mixed-matrix membrane vs. permeability ratio of continuous phase to dispersed phase, selectivity of dispersed phase 35, selectivity of continuous phase 7. 

Traditional particulate fillers tend to agglomerate already during manufacture, and once agglomerated, it is difficult to subsequently disperse them. Dispersion requires addition of a dispersant additive (e.g., stearic acid or alkysilanes) and the input of energy to overcome the attractive forces between particles [6]. The correct selection of dispersant type and application method is crucial. In contrast, POSS as synthesized, already possesses its own intrinsic dispersant in the form of covalently bonded organic groups and dispersion is easy. 

An important criterion for the selection of dispersion instmments/machines is the energy consumption required for a certain change in size distribution. 

Because of the large amount of available data, only a selection of dispersion curves and surfaces has been given. For more detailed information, the reader is referred to [2.10,11]. 

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