THE INFLUENCE OF STATE-OF-MIX ON THE EXTRUDATE SWELL OF A CARBON BLACK-FILLED STYRENE-BUTADIENE RUBBER COMPOUND

The factors which govern the extrudate swell of a styrene-butadiene ru bber compound filled with 30 phr of N330 carbon black at various state s-of-mix were investigated. The state-of-mix is quantified by an effec tive filler volume fraction, based on an estimate of the amount of rub ber immobilized in the carbon black agglomerates. The swell has been f ound to be dominated by recoverable strain and relaxation time, which are both controlled by the effective filler volume fraction. In contra st, shear rate, wall slip, and the rubber-carbon black network have no t been found to have a significant effect on the extrudate swell. (C) 1997 John Wiley & Sons, Inc.