Microstructural studies of the interactions in SB rubber and mesoporous silica mixtures

Precipitated silicas have been utilized successfully as rubber reinforcing fillers instead of carbon black. The development of new mesoporous silicas with properties different than the precipitated silicas, specially their high BET surface areas and their organized pore structures with pore sizes between 1.5–10 nm, make them potential materials in rubber reinforcing. The knowledge of the interactions between rubber and its filler at a fundamental level is important to understand the physical and mechanical properties of a filled rubber system. This paper presents a comparative microstructural analysis of the interactions of the styrene butadiene rubber (SBR) with mesoporous silica and with Ultrasil VN3 silica, made on mixtures prepared in a rheometer at 150 °C and their toluene extracted residues. Solid state nuclear magnetic resonance, Fourier transform infrared (FTIR), thermogravimetry (TGA), scanning electron microscopy (SEM) and nitrogen adsorption isotherms, show a relation between the strength of the interaction and the particle size and pore structure characteristics of the mesoporous materials. Such a material prepared under certain specific conditions shows better interaction with the rubber than Ultrasil VN3 silica.