Effect of Filler-Elastomer Interactions on the Mechanical and Non-Linear Viscoelastic Behaviors of Chemically Modified Silica Reinforced Solution-Polymerized Styrene Butadiene Rubber

Since the introduction of the so-called ‘Green tire’ by Michelin, precipitated silica has been proved to be the filler of choice for the manufacture of high performance pneumatic passenger car tires. Silica as a reinforcement agent provides a combination of good mechanical properties, high resilience, excellent rolling resistance and low heat build-up. The significant reinforcing effect exhibited by silica contrasts with the difficulty on the processability of the silica-filled rubber compounds because of the poor dispersity of silica particles in the rubber matrix. In the present paper, we explore the effects of surface modification of silica on mechanical and non-linear viscoelastic behaviors of solution-polymerized styrene butadiene rubber (SSBR) filled by modified silica (M-Silica). Compared with pristine silica filled SSBR, SSBR reinforced by M-Silica presents not only better filler dispersity and mechanical properties but also lower internal friction in the certain temperature range. The cure kinetics was investigated in term of curemeter, and the kinetics parameters of SSBR/M-Silica were found to vary from those of SSBR with pristine silica, indicating that SCA molecules grafted on the silica surface provoked an enhanced mobility of rubber chain adsorbed onto filler surface and then decreased the barrier of crosslink reaction. Analysis using tube model theory provided more evidence for the reinforcement effect of M-Silica. SSBR containing M-Silica exhibited a combination of increments in topological tube-like constraints and crosslink density in comparison with SSBR filled with pristine silica. Strain dependence of dynamic modulus revealed that the secondary network formed by silica particles was destroyed to some extent with the increase of the hydrophobic character of silica surface. Loss factor of SSBR/M-Silica was dominated by different mechanism in different temperature range, i.e. secondary filler network at glass transition temperature and rubber-filler interaction and entangled structure above room temperature.