Structure of aggregate and agglomerate

Reprinted with permission from A. I. Medalia, Rubber Chemistry and Technoiogy, 1974, 47, 2, 411. Copyright 1974, Rubber Division of the ACS. 

The application of fractal analysis enabled the characterisation of the aggregates, which by nature consisted of wide varieties of size and shape. 

For very practical reasons simple tests are needed to determine the surface area and structure of fillers. However, defining the test condition is not without problems. The surface area based on a monolayer adsorption of a small molecule depends upon the size of the adsorbent molecule, because the filler surface is made up of irregular topology. 

A practical definition of surface area must be related to the adsorption of rubber molecules. Upon consideration the current choice of adsorbent is cetyltrimethylammonium bromide (CTAB). However, nitrogen adsorption (BET) is also in common use. 

The structure determination utilises absorption of liquid into pores of agglomerate. Therefore, it depends not only upon the structure of the aggregate but also how tightly aggregates are packed in an agglomerate. The usual procedure is to compress the sample under a very high pressure prior to the absorption of DBF [30]. More detailed discussion on the surface area and structure are given by Donnet and Voet [1]. In addition to the 

---

Data presented in Table 1 show that depending on the kind of oxide matrices (polymer type (with polar or nonpolar groups), and deposition technique, we obtain carbon-silica materials of different porous structure and carbon content. 

---