Résumé
The structure of styrene-butadiene (SB) nanocomposites filled with industrial silica has been analyzed using electron microscopy and small-angle X-ray scattering. The grafting density per unit silica surface rho_D3 was varied by adding graftable SB-molecules. By comparing the filler structures at fixed rho_D3 (so-called 'twins'), a surprising match of the microstructures was evidenced. Mechanical measurements show that rho_D3 also sets the modulus: it is then possible to tune the terminal relaxation time of nanocomposites via the chain length while leaving modulus and structure unchanged.