The relationships between state-of-mix, theologic properties, dynamic properties, and bound rubber content in N330 carbon black filled styrene butadiene rubber (SBR) were investigated. Shear viscosities measured from both Mooney viscometer and capillary rheometer decrease with increasing state-of-mix. By contrast, the stress relaxation determined from the Mooney relaxation viscometer (PR80) decreases with an increase in state-of-mix. In addition, glass transition temperature (TR) is not strongly affected by a change in state-of-mix, whereas the magnitude of damping peak (tan delta) increases with state-of-mix. Bound rubber content appears to decrease as the state-of-mix increases. The concept of a change in an amount of immobilized rubber can be used to explain the results obtained. (C) 2000 John Wiley & Sons, Inc.