Nanocomposite of SBR/Hydroxy-terminated Polybutadiene Grafted- Fumed Silica

Modified fumed silica, grafted by hydroxyl-terminated polybutadiene
(HTPB) via toluene diisocyanate (TDI) bridging, was incorporated in
styrene butadiene rubber (SBR) as reinforcing filler. The main objective
of this work was to study the effect of the modification method on final properties of the rubber compounds. As compared to unmodified nanosilica, scanning electron microscopy (SEM) represented nano dispersion of modified fumed silica particles in SBR compound. The results of mechanical uniaxial tensile test revealed the significant reinforcement property of HTPB-surface grafted nanosilica. This strong effect is attributed not only to nanodispersion of silica particles but also due to participation of HTPB double ligands in sulfur curing system of SBR and chemical linkage between rubber matrix and silica particles. The study of dynamic mechanical properties under temperature scan (linear viscoelasticity) displayed strong interaction between the rubber matrix and modified silica particles and it again reaffirmed the efficient reinforcement effect of this filler. Also, dynamic mechanical properties under strain scan (non-linear viscoelasticity) exhibited filler network formation at low filler content for this modified nanosilica. Surface modification of nanosilica by HTPB grafting intensified the mechanical reinforcement of the filler; meanwhile, it reduced the intensity of non-linear behavior by weakening the effect of filler network break down (Payne effect) relative to that of unmodified silica. Therefore, this method of silica surface modification could be a novel method in improvement of the final properties of filled SBR by nanosilica.