Microdispersion of Silica in Tire Tread Compounds Above the Percolation Threshold by Tem Image Measurements

Abstract

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.

The influence of kaolin and calcined kaolin on SBR composite properties

“…The minimum torque ( M L ) is related to the viscosity of composites, it is noticed that M L increased with increasing filler loading for all compositions of kaolin while for SBR/calcined kaolin composites M L increased up to 30 phr and then decreased. Also, M L for SBR/calcined kaolin seems to be greater than that of M L for SBR/kaolin, this increase is related to agglomeration between aggregates of kaolin occurred by means of direct contact through hydrogen bonding . The addition of smaller size filler particles tends to impose extra flow resistance due to higher molecular motion restriction of the macromolecules; hence higher viscosity can be detected .…”

Elucidation of filler-to-filler and filler-to-rubber interactions in silica-reinforced natural rubber by TEM Network Visualization

“…Transmission Electron Microscopy (TEM) was used by Julve et al [13] to evaluate the microdispersion of silica in a silica tire tread compound with a high filler content. Reuvekamp [14] found that a better silica microdispersion is obtained at high discharge temperature after mixing, as characterized by an increase in the amount of segregated silica particles.…”

Analytical method development to predict the in-rubber dispersibility of silica

“…It seems to be that for higher filler loadings, reliable and reproducible results cannot be obtained [108]. However, Julve et al [109] published a paper including a method to determine the dispersion quality of silica in a highly loaded vulcanized compound.…”