THE EFFECT OF CARBON-BLACK CONCENTRATION ON THE DYNAMIC MECHANICAL-PROPERTIES OF BROMOBUTYL RUBBER

The effect of carbon black concentration on the dynamic mechanical properties of bromobutyl rubber vulcanizates has been studied over a wide range of temperature ( - 150 to + 250-degrees-C), frequency (3.5 to 110 Hz) and dynamic strain amplitude (0.07 to 5%). The influence of carbon black concentration on the glass-rubber transition has also been investigated with respect to the isochronal variation in dynamic properties. The influence of carbon black concentration consists mainly of the change in the levels of the moduli values in the glassy and rubbery state. In the glassy region; the increase in stiffness with carbon black loading may be fully explained by the hydrodynamic effect of the carbon black particles embedded in the polymer continuum. With increased carbon black concentration the glass-rubber transition temperature (tan delta peak temperature) does not show a shift in its location but peak shoulder broadening and decrease in peak height are observed. At a particular temperature, the effect of carbon black concentration on dynamic properties of bromobutyl rubber is dependent on the combined effects of applied strain amplitude and frequency. With increase in filler concentration the thermal stability of the vulcanizate increases.