Black incorporation time

Black incorporation time is less in case of masterbatch. 

Figure 18.16 shows that carbon black incorporation time, BIT, is affected by the addition of ZnO and by the properties of carbon black. If no ZnO is added, the incorporation time decreases as the carbon black structure increases. The opposite is true when ZnO is present during carbon black dispersion. The overall quality of the dispersion improves when ZnO is present and when mixing is carried out at elevated temperature Dispersion quality was assessed by optical measurements. 

Figure 18.16. Carbon black incorporation time vs. DBPA adsorption. [Adapted, by permission, from Urabe N, Takatsugi H, Ito M, Toko II. Fukui M, Int. Polym. Sci. Technol., 22, No.5, 1995, T/68-72.]...

The rotor speed also influences carbon black incorporation time (Figure 18.18). The characteristics of both relationships are similar but longer times are required to disperse rubber with no ZnO added. 5... 

Changes in conductivity dming mixing of a compound have been examined as an on-line device for measming black dispersion (197), and it would appear from work carried out in a Brabender mixer that there is a correlation between compoimd conductivity and mixing torque. The value appears to be in measuring black incorporation time, but whether this could be developed into a suitable on-line test for use industrially remains to be seen. 

Using the mixing method described in the previous paper in this series, which produces reproducible data, the authors investigated each factor that affects the black incorporation time. Various carbon blacks, oil-extended rubber and oil were used as the materials in the tests. The mixing conditions used were the rotational speed, rotational ratio of the rotor, fill factor and ram pressure. The authors studied the effect of these factors on the black incorporation time by the new theory based on static electricity phenomena and rabber viscoelasticity. 7 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. 

A smdy is described of the mixing of SBR-caibon black system in an internal mixer. The effects of addition of zinc oxide and increase in tempeiatnrc on the black incorporation time are compared. 8 refs. Articles from this journal ean be requested for translation by subscribers to the Rapra produced Intemational Polymer Science and Teehnology. 

Fig. 1. Bra bender Plastograph mixing curve for 137-5 parts SBR 1712 plus 69 parts N-339, mixed at 50rpm, 138°C, upside down (black added first). Curve area (area below top trace) = 3-9mkgmin, = 2120MJ/m. (a) Ram lowered, (b) black incorporation time or second power peak, (c) / point, (d) dump. Reproduced with permission from Rubber Chem. Technol ...

Using the Brabender Plasti-corder the black incorporation times for natural and synthetic polyisoprenes may be measured (Fig. 4). It can be seen that absorption and dispersion of filler is, as expected, much faster with the synthetic polymers. 

Fig. 4. Brabender Plasti-corder black incorporation times (BIT) for SMR L and Natsyn 2200 (polymer, 100 N-330 black, 50 speed, 100 rpm starting temperature,...

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