Characterization of kaolinite/styrene butadiene rubber composite: Mechanical properties and thermal stability

• Rubber chains were confined within the interparticles space of kaolinite.
• Kaolinite could reduce scorch time and cure time of kaolinite/SBR composites.
• Kaolinite significantly improved mechanical property of kaolinite/SBR composites.
• Kaolinite/SBR composites exhibited significant improvement in thermal stability.

The processing, mechanical properties and thermal stability of kaolinite/styrene butadiene rubber (SBR) composite were investigated, and the influences of kaolinite particles size and filled contents on these properties were analyzed. The X-ray diffraction (XRD) patterns, Fourier-transform infrared (FT-IR) spectroscopy, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) showed that the rubber chains may be confined within the interparticles space and the kaolinite particles presented a physical dispersion in SBR matrix. The scorch time (ts2) and cure time (tc90) of the kaolinite/SBR composites decreased simultaneously relative to those of the pure SBR. The minimum torque of the kaolinite/SBR composite increased relative to that of pure SBR, and it decreased with decreasing filler particle size and increased with increasing filler content. The modified kaolinite gave a progressive reinforcement on mechanical properties of the kaolinite/SBR composite, even at high filler content (80 phr).The tensile strength and tear strength of the kaolinite/SBR composite at 80 phr filler loading were 19.62 MPa and 40.63 kN/m respectively. The prepared composite exhibited significantly improvement in thermal stability compared with that of pure SBR. The characteristic decomposition temperatures of kaolinite/SBR composite gradually increased with decreasing particle size and increasing content. The improvement of mechanical properties and thermal stability of kaolinite/SBR composite is attributed to the fine dispersion of kaolinite particles in the rubber matrix and the strong interactions between kaolinite particles and rubber chains.