Carbon black structural parameters

The distance between aggregates is a value which correlates with many properties of filled rubber. Figure 7.35 gives an example of the correlation with tanb. " Other applications were made with these properties ball rebound, effect of graphitization on properties of carbon black and parameters of carbon black which characterize structure. 

Eq. (32) contains no parameters characteristic of the filler. If it successfully represents data on one carbon black, then it should also do so for other blacks, irrespective of particle size or structure. The author s fragmentary data (212) on large particle furnace blacks indicates that this is true. The effects of carbon black structure at constant particle size are shown in Fig. 23 with data on the four carbons of Fig. 11. Although there is some scatter in the experimental points there is no systematic deviation by black structure. The line drawn through the data agrees nearly quantitatively with that of Harwood and Payne. 

In simplistic terms, the particles can be thought of as being similar to carbon blacks, and to consist of very small primary particles that are aggregated into larger structures and which are the effective particles. The primary particle size is in the range 5-100 nm and the aggregates can contain several hundred primary particles. The way in which the primary particles are combined in the aggregates can vary from open, chain-like structures, to denser, spherical structures and this will very much affect both their physical properties and performance. As with the carbon blacks, structure is a very important parameter and is usually measured by an oil absorption method. 

Some of the above-mentioned parameters are tabulated for a few carbon blacks of very different morphology (Table 4). It appears that, in spite of its complex morphology, the structure of a black can generally be fairly well evaluated knowing its specific surface area and its DBP absorption capacity (DBP number)16). 

The three parameters, mean primary particle size (or specific surface area), structure (or aggregate size), and surface chemistry (e.g. surface oxides), largely determine the application characteristics of carbon blacks. A summary of how these parameters affect color and performance appears in Table 31. 

Only then a correlation of the LII results with the iodine number is to be expected if different specific surfaces are caused by variations in the primary particle size and not in porosity. The assumption that LII determines a measure for the enveloping surface without consideration of small porosities has been examined in further measurements at a test reactor of the Degussa AG with finer parameter variations. The aim was to manufacture carbon blacks of same primary particle size, but different surface structure. 

Using medium sized commercial reactors 100 different "grades" of carbon black were produced. Of course, these were not all commercial grades of black. Our objectives were two-fold. One, to establish the operating parameters to insure we fully understood the ranges of particle size, structure, and surface area which could be produced as independent variables and, two, to establish grades of... 

In order to produce a carbon black to any specification, the relationships between particle size, structure, and surface area allow the predetermination of performance parameters desired in a rubber compound, before and after vulcanization. 

On the basis of the results of investigations on a large number of commercial carbon blacks synthesized under various conditions it was established [60] that the microtexture of all the materials could be described in terms of the characteristics represented in Fig. 1. Depending on the production method of a material its parameters L, Li, and y may vary. A decrease in y and an increase in L give evidence for the ordering of the particle structure. Figure 2(a) displays a schematic view of a section of a carbon black particle, where individual crystallites are visible [60]. The surface of each of the crystallites visible in this figure has a turbostratic structure. 

Let us now examine practical examples of carbon blacks chosen from the range of products of the Cabot Corporation, which were selected to show a variety of carbon blacks in respect to their structure and particle size (Table 2.3). Table 2.3 shows that because each carbon black differs in particle size, particle porosity, and aggregate structure, the relationship between parameters caimot have a high correlation. 

Research on carbon black continues and the most important topic remain its structure, the effect of functional groups on carbon black properties, the effect of the measured parameters of carbon black on its performance in various systems, and the influence of processing parameters on the product. These and other influences are discussed throughout the book. 

Void volume is one of the main parameters used to characterize the structure of carbon black. " Void volume enters into the equation used to characterize interaggregate distance, lAD, as follows ... 

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