Investigation on elastomer-silica interactions by inverse gas chromatography and image analysis aided transmission electron microscopy

A study on the interactions between silica and elastomers typically used in tire tread production has been carried out by inverse gas chromatography (IGC) and image analysis aided transmission electron microscopy (TEM/AIA). IGC at infinite dilution has been performed using precipitated silica as the stationary phase, to determine its surface properties and to calculate the adsorption free energy and enthalpy of low molecular weight analogues of elastomers, used as the eluates. Vulcanized samples based on different matrices employed in tire formulations, i.e. natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR) have been investigated by TEM/AIA to determine the dispersion of the filler within the matrix as well as to achieve quantitative information on aggregate size and shape distribution of silica and, consequently, on the polymer-filler interactions. A comparison between thermodynamic predictions deduced by IGC and the results from morphological analysis concerning filled compounds shows a very satisfactory agreement.