Silane-grafted silica-covered kaolinite as filler of styrene butadiene rubber

The use of silylated kaolinite/silica (SMKS) particles as reinforcing materials for styrene butadiene rubber (SBR) was studied. The transmission electron microscopy (TEM) revealed that a layer of ultrafine silica particles was deposited on the kaolinite surface. The Fourier transform infrared (FTIR) spectroscopy also indicated the grafting of the silane onto the silica coated kaolinite particles. To evaluate the improved properties of SMKS filled SBR composite, samples filled with unmodified kaolinite (ORK), silane modified kaolinite (SMK) and precipitated silica (PS) were also analyzed. The composites were characterized by scanning electron microscopy (SEM), thermal analysis and mechanical properties analysis. SMKS had a great effect on the thermal properties, and achieved high performance and pronounced mechanical properties. The stress at a strain of 300% and 500% and the tensile strength of the SMKS-rubber were much better than the rubber loaded with SMK and ORK. The tensile strength of the SMKS filled rubber reached to 15.5 MPa, much higher than that of SMK (11.6 MPa) and ORK (9.9 MPa). The mechanical analysis indicated that 50 phr PS can be replaced by 50 phr SMKS without affecting the properties of the final material.

► Silylated kaolinite particles were prepared via sol-gel technique.
► The elongation at break and stress at strain of 300% and 500% of SMKS filled SBR are almost the same with that of precipitated silica filled SBR.
► The thermal stability of SMKS filled SBR is greatly improved compared with that of PS filled SBR.