It is considered that, in the mixing process of carbon black filled rubber systems, the degree of polymer-carbon black interactions and the degree of carbon black dispersion in polymer proceed at the same time. If these structural changes are evaluated respectively, it is considered possible to quantify the kneading state of the rubber compound more precisely. Attention is paid here to the dynamic viscoelastic properties with the rubber compound.
It was found that an apparent activation energy (E_a) calculated from the temperature dependence of dynamic viscosity modulus is an effective index for measuring the degree of polymer-carbon black interaction. And carbon black dispersion was quantified by dynamic elasticity modulus change ratio (G_r) at dynamic elastic modulus (19.98%) versus that (0.98%), taking notice of Payne effect. These indices can be calculated simply and easily from dynamic viscoelastic property measurements. This testing method can be applied to estimate the kneading state of the rubber compound.

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Haigoshi, or alchemistic compounding specialists are described. Their extinctions are reviewed in relation to the transition of compounding design, especially the popularization of accelerators at Taisho and Showa periods.

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Ultra-fine precipitated calcium carbonate (UFPCC) can be used not only as “Filler” but also as “Functional additive”. A small dosage of UFPCC together with reinforcing fillers (such as precipitated silica, carbon black which are difficult to mix or disperse) can act like a dispersing agent or processing aid, and to shorten the mixing time/to improve the dispersibility of reinforcing fillers can be expected.
In addition, UFPCC can improve the tackiness and elongation of unvulcanized rubber and it is supposed that these advantages may accelerate the mixing of fillers/rubber and extension of rubber together with filler which results to shorten the mixing time and to improve the dispersibility of reinforcing fillers.

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