Polymer–filler interaction of fumed silica filled polydimethylsiloxane investigated by bound rubber

In this work the polymer–filler interaction between polydimethylsiloxane (PDMS) and fumed silica was discussed and a double-layer interfacial structure was established. Then excess energy and bound rubber were adopted to characterize the polymer–filler interaction. Bound rubber (BR) was measured by thermogravimetric analysis (TGA) of a series of extracted solids containing fumed silica particles and unextractable PDMS chains. Experimental results showed that the amount of bound rubber was slightly affected by filler's dispersion but greatly affected by filler's concentration, specific surface area and surface chemistry. It was also found that, due to the formation of constrained chains, bridging chains and occluded rubber, the amount of bound rubber could only roughly weigh the total polymer–filler interaction.