2006 Volume 79 Issue 11 Pages 516-520
Styrene-butadiene rubber (SBR) was mixed with carbon black (CB), zinc oxide, etc. using 10L and 75L conventional kneaders equipped with conventional rotor, and 7L and 55L novel kneaders with new type rotor. The new type rotor used in this study has a large rotating shaft in comparison with the conventional type rotor. These rotors were installed in the same vessels, respectively. Under various rotating speeds and shear rates in the tip, Mooney viscosities and volume resistivities of SBR compounds were measured at arbitrary rotor revolutions. By using the new type rotor, it is thought that mixing will proceed not only in the tip region called the high shear region, but also in the annulus called the low shear region.
Mooney viscosities of compounds obtained by 55L kneader were lower than that by 75L kneader. Volume resistivities of compounds obtained by novel kneaders were higher than those by conventional kneaders.
At the initial stage of mixing in the novel kneader, it is supposed that most of CB was incorporated into SBR in the annulus to form the loose agglomerates of CB in rubber. This may be due to the low shear rate. Then the agglomerates will be collapsed to the fine aggregates of CB in rubber through subsequent mixing.
