Analysis of the formation of bound poly(dimethylsiloxane) on silica

The kinetics of adsorption of poly(dimethylsiloxane) (PDMS) on silica particles was studied. A theoretical model was developed and fitted to different sets of experimental data to investigate the dependence of model parameters upon polymer and filler characteristics. In the model, the formation of bound polymer was pictured as a second-order reaction process with a rate proportional to both the number of available binding sites on the filler surface (silanol groups) and the number of free (unbound) polymer chains surrounding silica particles. The assumption was made that these two limiting factors had the same effect on the adsorption rate of bound rubber. This model proved to be well adapted to a wide range of material parameters for mixtures containing less than 30 wt% of silica. (C) 1998 Elsevier Science Ltd. All rights reserved.