Dynamic mechanical properties of filled styrene butadiene rubber compounds:: comparison of tensile and shear data

Most rubber articles are prepared from filler-elastomer compounds and dynamic mechanical data can give valuable insight into behavior of such systems. The aim of this study was to compare complex tensile modulus E* and complex shear modulus G* using seven types of vulcanized filled rubbers and two testing devices. Carbon black and clay filled styrene butadiene rubber (SBR) compounds were tested. The E* value was measured using a dynamic mechanical analyzer (DMA DX04T from R.M.I.) and the G* value using a rubber process analyzer (RPA 2000 from Alpha Technologies) at 1 Hz, 30 degrees C and at small deformation amplitudes common to both devices. For characterization of tested materials absolute values of complex modulus \E*\ and \G*\ were used together with values of loss factor tan delta. The highest values of \E*\, \G*\ and tan delta in tested carbon blacks were obtained for type N330. The highest values of \E*\, \G*\ and tan delta in tested clay fillers were found for organoclay Cloisite 93A. Maximum at the dependence tan delta/amplitude, obtained in a broader shear amplitude range, was found to be smaller for carbon black filled compounds than expected and maximum at this dependence for clay filled compounds was not observed. The amplitude dependences of analogous dynamic mechanical characteristics from dynamic mechanical analysis (DMA) and rubber process analysis (RPA) measurements seem to be similar. Between the analogous dynamic mechanical characteristics from DMA and from RPA usually a linear relationship exists with high correlation coefficient. Conclusions derived from DMA and RPA testing on the same series of rubber compounds seem to be the same. Copyright (C) 2006 John Wiley & Sons, Ltd.