Aggregation, silica

The monodisperse non aggregated silica sphere slabs undergo only intrusion during mercury porosimetry experiments. Due to the very compact arrangement of the spheres, the pore volume Kng is very small (table 2). Ing increases when the size of the spheres increases from 8 to 206 nm. 

The results with the slabs of monodisperse non aggregated silica spheres (of the same size range than the xerogels and aerogels) which undergo only intrusion during mercury porosimetry implies that the particles need to be aggregated so that the compaction mechanism takes place... 

Mixing into cement mortar as filler material replacing aggregate (silica)... 

This shows that FRP mortar is lightened and strengthened by heating. As it was considered that compactification of FRP mortar is necessary for its strengthening, compactifications by pressurization and by the use of fine aggregate (silica fume) were examined. 

It is particularly good for colloids, emulsions and particles. Samples separated thus far include lattices, latex aggregates, silica sols, alkyd resins, perfluorocarbon emulsions, milk, carbon particles, hematite, clay, water-borne particles, liposomes, subcellular particles, viruses, and polymerized proteins. 

Another relevant system involves oleic acid (OA) adsorption at the silica-water interface. This method was first demonstrated by Ding et al. [45] and was next used by Mahdavian and coworkers to encapsulate very small silica nanoparticles [46]. In the latter case, a core-shell structure with a core composed of aggregated silica particles and a shell made of MMA, styrene and acrylic acid (AA), was formed. The authors suggest that the polymerization proceeds through oligoradical entry into the OA admicelles. 

The acid-catalyzed polycondensation of tetraethoxysilane, a silicic acid precursor, results in the formation of an aggregated silica gel (Figure 1). Con aratively, the three-dimensional structure of die aggregated silica gel was similar to the natural morphologies of the silica particles catalyzed by proteins (9) and polypeptides (12J3J7). Furthermore, e use of external force was demonstrated (21) to control the morphology (e.g. arched, fibrillar) of a silica material catalyzed by a biomimetic silaffin peptide (i.e. a non-modified Sil Ip R5... 

Figure L Acid-catalyzed formation of an aggregated silica gel...

A. Vital., U. Klotz, T. Graule, R. MueUer, H. K. Kammler, andS. E. Pratsinis, Synthesis of spherical, non-aggregated silica nanoparticles , NATO Advanced Research Workshop Nanostructured Materials and Coatings for Biomedical and Sensor Applications, Kiev, Ukraine, August 4—8 (2002) in Nato Science Series, II Mathematics, Physics and Chemistry, 102,203-210 (2003)... 

FIGURE 9.17 Schematic diagram representing the ion condnction channel in (a) Nafion and blockage of the ion conduction channel in the hybrid membranes due to the presence of (b) aggregated silica and (c) nanoclays. (From Mishra, A.K. et al.. Prog. Potyrn. ScL, 37, 842, 2012.)... 

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