The structural, rheological, and electrical characteristics of carbon black (CB) suspensions with different oxidation degrees of particles have been studied in polar and apolar media. The structural charac teristics have been determined for individual particles and particle aggregates of CB in a powdered form and in dispersion media. The yield stresses of CB suspensions in Vaseline oil (VO) and castor oil (CO) increase with the oxidation degree of particle surface; however, at the same oxidation degree of particles, the yield stress of suspensions in VO is, as a rule, lower than that in CO. In all suspensions, the calculated sizes of sec ondary aggregates decrease with a rise in the CB oxidation degree; however, at the same oxidation degree, the secondary aggregates in suspensions in VO are, as a rule, larger than those in suspensions in CO. Possible mechanisms of the electrical conductivity of the suspensions have been considered both at rest and under dif ferent regimes of dynamic actions. An interpretation has been proposed for the appearance and shifts of dila tantcy peaks for CB suspensions as depending on the oxidation degree of CB particle surface and the nature of a dispersion medium.
SOBOLEVAccording to [4,5,20,21], stable surfactant free suspensions with structures of different strengths may be produced based on nongraphitic CBs with different ODs.EXPERIMENTAL CB samples with different ODs were obtained as follows. Initial sample (CB1) with an oxygen content of 0.5 wt % was thermally oxidized in air using a fluid ized bed process until the oxygen content reached 4.2 and 19.7 wt % (CB2 and CB4 samples, respectively). In addition, the CB5 sample with an oxygen content of 0.06 wt % was obtained by thermal treatment of CB1 at 900°C in a hydrogen flow.The physicochemical properties of these CB sam ples were analyzed in detail elsewhere [21]; the results obtained are presented in Table 1. The sizes (D a ) of CB particles forming primary aggregates were determined by transmission electron microscopy (TEM)