Tensile properties of fumed silica filled polydimethylsiloxane networks

Tensile properties of fumed silica filled hydroxylated polydimethylsiloxane (PDMS) networks were investigated in the current work. Similar to unfilled bimodal networks, unimodal networks filled with concentrated fumed silica exhibit non-Gaussian effect and improved ultimate tensile properties. The concept of “hierarchical network” was proposed to depict the networks exhibiting non-Gaussian effect at sufficiently high strains. It was found that the reinforcing effect originates from both the effective volume effect from filler volume and polymer-filler interaction and the synergistic effect between network chains within the “hierarchical network”. Experimental results showed that filler's dispersion, concentration, specific surface area and surface chemistry have a great influence on the tensile properties, which could be interpreted by analyzing the variation of both effective volume effect and synergistic effect.