Particle surface coatings

Heat and mass transfer between particle/ particle or particle/surface Coating of pharmaceutical tablets Granulation Mixing of solids Plastic coating of surfaces... 

VanBerkel, J. and Beckett, R., Estimating the effect of particle surface coatings on the adsorption of orthophosphate using sedimentation field-flow fractionation, J. Liq. Chrom. Rel. Technol., 20, 2647, 1997. 

Nano-milled drug substance particles surface coated with polymer(s) for stabilization. 

Fossil bone chemistry as a paleoredox indicator. Uniquely among the REE, cerium has the capability to adopt a tetravalent ion under the appropriate oxidizing conditions. The oxidized form of Ce (Ce" ) is relatively insoluble compared to Ce (de Baar et al. 1985), so that cerium takes part in active redox cycling. Under oxic conditions, Ce exists in the tetravalent state, and is readily removed from solution either onto particle surface coatings, or into authigenic minerals (Sholkovitz et al. 1993, Koeppenkastrop and... 

Droplet Size Droplet size was determined on a Van tan Coulter counter (Model 4000, Zymo Instruments, India) after diluting the multiple emulsion 100 times with an external phase. The droplet size ranged from < 1.0 to 1.93 pm. Table 9.1 shows the droplet size and the polydispersity of the multiple emulsion formulations. The particle sizes of 6-MP loaded, coated, and uncoated multiple emulsions was nearly the same. The mean diameter of PEG-coated multiple emulsions was found to decrease with time, and it reached its minimum size after 6 to 8 hours. The size was reduced by nearly 15%, and the polydispersity was decreased from 0.18 to 0.09. Kim et al. (1995) found the separation of the aggregated multiple emulsion droplets to occur over several days of equilibration. In our case, it was few hours because of steric stabilization of individual particles surface coated (Vanderhoff and El Asser, 1988). 

Acetic acid digestions of suspended particles demonstrate that removal and fractionation of lanthanides in seawater are caused by processes which result in particle surface coatings. In contrast, the detrital phases have dust and crust-like lanthanide compositions indicative of a continental source. 

Atlantic Ocean and the western North Pacific Ocean (as described in fig. 14). In both cases it is clear that Ce in upper water column is being removed from the dissolved phase. The study of particle surface coatings by Sholkovitz et al. (1994), (discussed in sect. 6.2), demonstrates in-situ oxidation of dissolved Ce to particulate Ce. As shown in fig. 20 with a Sargasso Sea profile, there is a large continuous increase in Ce associated with the surface coatings of suspended particles between surface and 500 m water. The in-growth of Ce in the upper 500 m of the water column corresponds with the subsurface maximum in particulate Mn oxyhydroxide (fig. 19), suggesting that the oxidation of Ce(lll) is directly coupled to the redox chemistry of Mn. 

Lubricants are added to lower interfacial frictional forces between individual particles and/or between particles and fonning die surfaces to improve compaction and ejection (i.e. extraction of the pressed compact from the fonning die). Individual particle surfaces can be lubricated by an adsorbed film that produces a smoother surface and/or decreases interiDarticle attraction. Fonning (die) surfaces can be lubricated by coating with a film of low-viscosity liquid such as water or oil. 

Insoluble Ammonium Polyphosphate. When ammonium phosphates are heated ia the presence of urea (qv), or by themselves under ammonia pressure, relatively water-iasoluble ammonium polyphosphate [68333-79-9] is produced (49). There are several crystal forms and the commercial products, avaUable from Monsanto, Albright WUson, or Hoechst-Celanese, differ ia molecular weight, particle size, solubUity, and surface coating. Insoluble ammonium polyphosphate consists of long chains of repeating 0P(0)(0NH units. 

Surface Coating. A dense surface coating (encapsulation) that contains no occluded solvent decreases interparticle attraction provided that the coating has a Hamaker constant intermediate between the particle and the Hquid. This is called semisteric stabilization (ST). The energy of interaction between coated spheres is as follows (26) ... 

Reaction spraying is also being widely explored. In this case new compositions or particle surface reactions providing enhanced coating properties, eg, nitrides for wear resistance, are achieved while the particle is in transit. 

After the wood particles are coated with resia, the particles are uniformly distributed iato a board by an air laid process. The art of the process is ia controlling and getting a uniform distribution of the wood particles by blowiag them out onto a collection chain. After forming the board shape it is moved to hot presses where the wood particles are consoHdated and the resia cured. From the hot presses the boards move to trim saws where the boards are cut square to their fiaal size. Ia some cases, the boards are sanded to final thickness and surface smoothness. 

In these cases, the polymer remains processible in the gelled state, because it is in the form of discrete PSA particles dispersed in the reaction medium. However, once the particles are dried, redispersion may be difficult if strong interactions develop between the particle surfaces. Polymerization of the acrylic PSA directly on the substrate, as in the case of UV polymerization, can also yield a covalently crosslinked polymer that does not require any further coating steps [71]. 

The physical properties of the base pigments produced from both processes are further improved by sluirying in water and selectively precipitating on the finely divided particles a surface coating of Si02, AI2O3. or TiOi itself. 

A chemical treatment designed to prevent the coagulation of colloids by the provision of a surface coating onto the colloidal particles. 

---