Abstract The temperature dependent flocculation behavior of hydrophilic precipitated silica filled styrene butadiene rubber(SBR) under different processing temperature, have been investigated by using rheology, morphological analysis, and mechanical measurements. Dynamic temperature sweeps consisting of a heating and cooling cycle were conducted. The results indicated that flocculation of silica in SBR lead to irreversible elevated elastic modulus(G′) with increasing fractal dimension (Df) of aggregates, and the flocculation amplitude of unmodified silica is apparently higher comparing with that of modified silica in composites specially. In this study, silane coupling agent (NXT) is used as modifier, which possesses bis functional groups. Morphologies of silica filled SBR composites investigated by SEM indicate that silica can disperse well in SBR matrix when silica is modified. Tensile stress, flex cracking, and scorch mobilities tests both indicate that modified composites, or lower processing temperature will obtain superior processing and mechanical properties. These results suggest that modification and processing temperature both are important variable, which can be regarded as simple way to regulate the microstructure of silica filled styrene butadiene rubber composites, and the optimized mechanical properties can be gained. These evolutions can be ascribed to the variable filler – polymer and filler –filler interactions. Keywords Styrene–butadiene rubber Silica Rheological behavior Flocculation