Influence of surface-modification for calcium carbonate on the interaction between the fillers and polydimethylsiloxane

The surface of calcium carbonate ( CaCO3) particles was modified with stearic acid ( SA) and the chemical structures of the product were characterized by FT-IR analysis. The interaction between polydimethylsiloxane ( PDMS) and CaCO3 fillers with different surface character was investigated by means of dynamic rheological and bound rubber tests for uncured compounds and mechanical properties measurements for the corresponding vulcanites. The results of dynamic tests indicate that with the increase of SA mass fraction, the span of the linear viscoelastic region broadens and the height of the modulus plateau decreases. The reasons for these are ascribed to that the SA decreases the surface energy of filler particles and weakens their tendency to agglomerate. Moreover, the results of mechanical measurements reveal that the vulcanized compound filled with modified filler has a relative high tensile strength induced by a reinforced interaction between filler and polymer matrix, which is confirmed by the bound rubber tests and transmission electron microscopy ( TEM) observations.