Mechanical Properties and Thermal Stability of Kaolinite/Emulsion Polymerization Styrene Butadiene Rubber Composite Prepared by Latex Blending Method

Abstract

This study focused on the preparation method and evaluation of micro-nano composites based on emulsion polymerization styrene butadiene rubber (ESBR) and kaolinite. A novel method – latex blending was utilized to improve the dispersion of kaolinite in matrix and obtain a semi-exfoliation type clay/polymer composite. The results showed that the kaolinite particles presented a semi-exfoliation state and micro-nano scale dispersion in ESBR matrix. The micromorphology of layer-like particles in rubber matrix presented loose and blurry attributed to the interaction between kaolinite plate-like particles and rubber molecules in the latex mixing process, and thus resulted in the reduction of kaolinite crystal order degree. The maximum torque (MH), minimum torque (ML), and ΔM presented a gradually increase tendency with the increase of filler content and the reduction of kaolinite particle size. The mechanical properties of kaolinite/ESBR displayed a significant improvement, and the relative mechanical parameters increased as increasing filler content or reducing kaolinite particle size. The tensile strength and tear strength of the kaolinite/SBR composite reached at 15.1 MPa and 51.3 kN/m, respectively when the filler content at 80 phr. The thermal stability of kaolinite/ESBR composites presented a considerably improvement as decreasing kaolinite particle size or at a reasonable range of filler content. The characteristic decomposition parameters of kaolinite/SBR composite increased compared with those of pure ESBR. The above data indicating that the ESBR chains interacted with kaolinite particles by chemical interaction and the polymer molecules may be intercalated the surface group and interlayer of kaolinite, and thus resulted in the transformation of layer-like microstructure and the restriction on motion of rubber chains in the composite system.