Hydrophobation of Silica Surface by Silylation With New Organo-Silanes Bearing a Polybutadiene Oligomer Tail

To enhance dispersion of silica into styrene-butadiene emulsion copolymer (e-SBR), used in tyres production, two new modifiers, characterized by 3-mercaptopro pyltrimethoxysilane grafted onto polybutadiene oligomers of <Mn> = 900 (sb1) and 5000 (sb3), were used. Silica was modified with several degrees of the two new silanes. Thermodynamic surface properties of the modified silicas were estimated by inverse gas chromatography as a function of the grafting degree of sb1 and sb3. e-SBR/silica compounds, with silica pre-modified and in situ modified during the mixing, were prepared and characterized using vulcanization tests, dynamic-mechanical analysis, and morphological observations by TEM. At degree of silylation lower than 10 wt%, the method of pre-modification allows a better dispersion of the silica within the elastomeric matrix and the best results were obtained using sb3. In particular, the lowest Payne effect, similar to that of a sample containing silica modified with bis-triethoxysilylpropyltetrasulfide, usually used in tyre production, was found for the sample containing silica grafted with about 10 wt% of sb3. (C) 2013 Society of Plastics Engineers