Dispersion and dynamic response for in-flame and chemically modified fumed silica nanocomposites

Surface modified silica fillers in polymer matrixes can display enhanced dispersion due to improved filler/polymer interactions which in turn impacts its dynamic response. Surface modification is usually achieved by chemical grafting of elastomer compatible moieties and silane coupling agents. It is also possible to deposit carbon directly during pyrogenic synthesis. In this study, in-flame and chemically modified pyrogenic silica fillers were dispersed in styrene-butadiene (SBR) rubber to explore their differences in nanocomposites. The impact of the surface carbon content on the extent of dispersion and rheological properties were explored. X-ray scattering results indicated that the in-flame and chemically modified fillers were well dispersed on the nanoscale in the SBR polymer matrix as inferred from the pseudo-second viral coefficient A_2. In previous work, we have demonstrated that pyrogenic silica displays correlations in similar nanocomposites due to the presence of silanol groups on the surface. Some of the in-flame coated silica fillers had sufficient surface carbon to mitigate the charge repulsion due to the silanol moieties. The efficacy of these carbon coated silica nanocomposites at exhibiting a balance between rolling resistance and wet grip was evaluated