Heterogeneous preparation and properties of nano-SiO2/cellulose composites

The nano-SiO2/cellulose composites were successfully synthesized by a sol-gel method using tetraethylorthosilicate (TEOS) as the silica precursor and cellulose in heterogeneous ethanol solution. The morphology, structure and thermal stability of the composite materials were characterized by TEM, FTIR and TGA. The influence of SiO2 content on the mechanical properties of composites was discussed. The effect of basic catalyst ammonia on the content of silica in cellulose was studied. The results indicate that the elastic modulus of the composites increases with the increasing of SiO2 mass fraction until 3.1% and then decreases, and the same is true of tensile strength when SiO2 mass fraction is 10.6%. SiO2 is incorporated into cellulose most effectively when the dosage of ammonia is 3.70 × 10-4 mol/L. The hydrophobicity, thermal stability and mechanical properties of nano-SiO2/cellulose composites in the heterogeneous system are also higher than those of the cellulosic materials.