MICRODISPERSION OF SILICA IN TIRE TREAD COMPOUNDS ABOVE THE PERCOLATION THRESHOLD BY TEM IMAGE MEASUREMENTS

摘要

Dispersion values in rubber are usually subjective values or the result of a comparison against empirical standards. we present a method to measure the filler dispersion in rubber compounds reinforced beyond the percolation threshold. Applying this method to an actual technical formulation with high filler loading, the dispersability of different silica grades, as well as the effect of coupling agent concentration in the dispersion has been showed. To carry out the measurements, the finished rubber is sliced in very thin films and then examined with transmission electron microscopy (TEM). Those images are processed to obtain information on the filler aggregation properties. As expected, the highly dispersible silica presents a smaller aggregate size and more contact surface with the rubber than the conventional and easily dispersible grades. In addition, increasing the amount of silane does diminish the aggregate size but with a lesser effect than that of the silica grade.