Particle Sizes of Fumed Silica

Abstract

Fumed silica is a synthetic amorphous silicon dioxide produced by burning silicon tetrachloride in an oxygen‐hydrogen flame. Surface areas range from 50–400 m2/g. Using particle sizing techniques, fumed silica shows micron sized particles leading to surface areas markedly lower than expected. Fumed silica appears as a fluffy solid with bulk densities down to 0.03 g/cm3, being invariant over the wide range of surface areas. Attempts to relate the variation of the surface area directly to the performance of fumed silica in technical applications, such as its thickening efficiency in fluids, mainly fail and remain ambiguous.

Application Relevant Characterization of Aqueous Silica Nanodispersions

“…As a reason for this difference we can discuss the nature of aerosil particles ( Figure 8) and as described. [17] Pyrogenic silica is produced from a high temperature hydrolysis of silicon tetrachloride in a hydrogen=oxygen flame. First, small primary particles (5-100 nm) are produced that collide and sinter to form fractal aggregates of 100-500 nm.…”

Effect of sub-micron silica fillers on the mechanical performances of epoxy-based composites

“…The silica N, exhibiting a specific surface area of 200 m 2 /g, was used as reference among unmodified silica for most experiments. For any SSA, the silanol content on silica surface is considered constant with a value of 1.8 SieOH per nm 2 [15]. At given silica content, the variation of the silica SSA implies a variation of the overall number of silanol groups able to develop interactions with the epoxy matrix.…”

Case Study – Characterization of Nanomaterials in Food Products

“…The appearance of the E551 food additive as aggregates is very typical for this substance, and is a result of the manufacturing process. 48,53 It can also be noticed that the majority of the particles, and even aggregates (as shown in Figure 1), were smaller than 100 nm. Thus the food additive used in this product would be classed as an NM.…”