Aggregate primary

Pigglomerates are undispersed clusters of aggregates held together by van der Waals forces or by biaders. The term stmcture is used to describe both the extent and the complexity with which the particles are iatercoimected ia aggregates. Primary measures of stmcture focus on the internal space within the aggregate. 

Precursors Temperature [K (°C)] Aggregate/ Primary Particle Diameter ( tm) Specific Surface area (m /g) Purity/Phase Composition... 

The cellulose fibrils of secondary cell-walls have a considerably greater cross-sectional area than those of primary walls,4,223 It is possible that primary microfibrils aggregate to form secondary-wall fibrils. Hemicelluloses trapped between aggregating primary, cellulose microfibrils may constitute the origin of a major proportion of the non-D-glu-cosyl residues of cellulose obtained from secondary walls. 

Fig. 34. Top Schematic view of a Ban ry Offo/n Evolution of the agglomerate size distribution with time predicted by the two-zone model with parameter values corresponding to the dispersion of carbon black in rubber in a Banbury muter. The size of an agglomerate after j ruptures is given by Dj — DQl2 i, where Do is the initial size of the agglomerates. The size of the aggregate (primary particle) corresponds to j = 28 (Manas-Zloczower, Nir, and Tadmor, 1982).

Ceramic powder Py aggregates Py primary particles aggregates primary particles m in equation 13.78... 

The experiments were carried out at pH 3 with the two smallest colloids (see Appendix 3 for preparation and characterisation). This extreme pH was required in order to obtain stable (non-aggregating) primary colloids, rather than their aggregates in the absence of organics (see Chapter 4 for characterisation of colloidal systems). Results are shown in Figure 7.42. At pH 3 the colloids have a high positive charge. This should lead to a significant repulsion between the colloids, increased backdiffusion, and therefore lower concentration polarisation of colloids (Bhattacharjee et al. (1999)). 

Figure 9.10 Surface area distribution based on spherical particles compared with the surface area distribution for silver aggregates using the theory of Lall et al. [138] for idealized aggregates. Primary particle size 18.5 3.5 nm. Reproduced with permission of Elsevier.

Figure 3. (a) Logaritmic scaling of an aggregate, part of an aggregate, primary particle and part of a primary particle. 

Diesel soot particles are almost entirely of respirable size, and consist of an elemental carbon core formed of aggregated primary particles and a variable amount of adsorbed organic sulfur, and metal compounds condensed onto the... 

---