Reinforcement of Elastomers by Carbon BlackGerard Kraus* (Received 27 Februar 1976) SUMMARY:The reinforcement of elastomers by carbon black is governed by the morphology of the black and its physical and chemical interactions with the polymer. The latter are strongly affected by graphitization and surface oxidation. In modern rubber-grade carbon blacks strong bonding of the polymer to the carbon black surface is effected by several mechanisms, but surface chemical differences between blacks are relatively small, so that the dominant characteristic becomes the morphology. This is determined by the average size and size distribution of the particles which are fused together to form primary aggregates resembling branched random coils, the spatial arrangement of the particles in these aggregates, and the number of particles per aggregate and its distribution. This highly complex morphology can, to a first approximation, be represented by the specific surface area accessible to rubber and some, usually indirect, measure of the volume pervaded by the primary aggregates ("structure"). Important mechanical properties of reinforced rubbers depend to different degrees on these two characteristics, often in rather complex manner. Their effects on viscoelastic and failure properties are described. Additionally, some very recent observations on the effects of carbon black on network structure and the influence of the breadth of the aggregate size distribution on viscoelastic behavior are discussed.
ZUSAMMENFASSUNG:Die Verstarkung von Elastomeren durch RUB wird durch die Morphologie des Ruljes und seine physikalischen und chemischen Wechselwirkungen mit dem Polymeren gepragt. Letztere werden stark durch Graphitierung und Oberflachenoxidation beeinflufit. In modernen Gummi-Ruljen werden feste Bindungen zwischen Polymeren und der Kohlenoberflache nach verschiedenen Mechanismen gebildet ; da die Oberflachen der RuDe chemisch nur wenig unterschiedlich sind, wird die Morphologie zum dominierenden Charakteristikum. Sie wird bestimmt durch die mittlere GroDe und die Groljenverteilung der Teilchen, die sich zu Primaraggregaten, ahnlich verzweigten statistischen Knaueln, zusam-
