Preparation and characterization of silica nanoparticles from sugarcane bagasse ash for using as a filler in natural rubber composites

Silica nanoparticles from sugarcane bagasse ash (SBA) were prepared from sol–gel process. Particle size, specific surface area, morphology, chemical composition and chemical structure of SBA and prepared silica nanoparticles were characterized. The effect of drying techniques such as freeze drying (FD) and heat drying (HD) on the properties of silica nanoparticles was investigated. High purity of silica nanoparticles in size range of 90 ± 10 nm were successfully prepared. FD provided silica nanoparticles with high specific surface area and high porosity compared to conventional HD. The effect of silica nanoparticle contents on cure characteristics, mechanical properties, and morphology of natural rubber (NR) composites was studied. Scorch time of NR composites was increased with an increase in silica nanoparticle content due to the disturbance of vulcanization process by silica surface. FD-silica/NR composites provided longer scorch time and cure time compared to HD-silica/NR composites due to higher active surface area of FD-silica. Modulus and hardness of NR composites were increased while elongation at break was decreased with an increase in silica nanoparticle content. Tensile strength of the composites increased with silica nanoparticle content and tended to reduce at high silica nanoparticle content. FD-silica/NR composites exhibited better mechanical properties than HD-silica/NR composites due to better filler-rubber interaction.