REINFORCEMENT OF STYRENE-BUTADIENE RUBBER VULCANIZATE BY IN-SITU SILICA PREPARED BY THE SOL-GEL REACTION OF TETRAETHOXYSILANE

In situ silica reinforcement of styrene-butadiene rubber (SBR) has bee n achieved by a sol-gel process using tetraethoxysilane (TEOS). SBR wa s sulfur-cured and the sol-gel reaction of TEOS was carried out in TEO S or in a TEOS-tetrahydrofuran (THF) mixture. The in situ silica was f illed homogeneously in the rubber matrix and the size of the in situ s ilica was influenced by the cross-linking density of the SBR vulcaniza te, n-Butylamine was effective for the method using TEOS only, whereas both hydrochloric acid and n-butylamine worked as catalysts under the experimental conditions using THF for the in situ polymerization of T EOS in the SBR vulcanizate. From the viewpoint of the reinforcement of in situ silica and the size stability of the SBR vulcanizate, the met hod using only TEOS was found to be better than the mixture system. Th is conclusion was based on the results of tensile tests, dynamic mecha nical measurements, optical and transmission electron microscopies.