DBP absorption

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). 

DBP absorption mL/100 g ASTM D 2414 ISO 4656 DIN 53601 determination of the wetting point with dibutyl phthalate in a special kneeder as a measure of the carbon black structure... 

ASTM No. Iodine adsorption mg/g DBP absorption ml/100 g Use in natural and synthetic rubber... 

Another important property is the structure (see Section 4.1) which characterizes the coalescence of primary particles into aggregates resembling chains or bunches of grapes. The dibutyl phthalate (DBP) absorption is commonly accepted as a measure for the carbon black structure. Due to absorption phenomena the DBP number increases with increasing specific surface area. Oil absorption (or, in general, the vehicle demand) is as well an indicator for the structure, but it also depends on the wettability of the black surface. Since linseed oil is a polar system, oil absorption declines as the concentration of surface oxides rises. 

Figure 26. Relationship of Iodine Number, DBP Absorption, ASTM Modulus and Running Temperature...

The method is based on the premise that all interstices, known as void volumes, in the carbon black aggregates are filled with DBP. The surface of the carbon black is considered to be wetted and this new surface state is translated into a change in the torque required for the kneading machine. The DBP requirement thus allows conclusions on the degree of aggregation of individual carbon blacks. The rule the greater the DBP absorption, measured in ml g , the higher the carbon black structure. 

Fig. 23. Representation of rupture energy data by Eq. (32) for carbon blades varying in structure. Various symbols represent different levels of DBP absorption...

Carbon black type Typical specific surface area m2/g Typical DBP absorption cc/lOOg... 

Very frequently, DBP adsorption is made with carbon black previously submitted to very high pressure into a cylinder for example, 24,000 psi four times (Creeden, 1997). Crushed DBP absorption or CDBPA is equal to DBP (for low structure carbon blacks) or significantly lower than DBP (for high structure carbon blacks). 

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