Sheykhnazari, S., Tabarsa, T., Ashori, A.*, Ghanbari, A.

International Journal of Biological Macromolecules 93: 672–677.

2016

The aim of this paper was to prepare composites of bacterial cellulose (BC) filled with silica (SiO2)nanoparticles to evaluate the influence of the SiO2contents (3, 5 and 7wt %) on the thermo-mechanicalproperties of the composites. BC hydro-gel was immersed in an aqueous solution of silanol derivedfrom tetraethoxysilane (TEOS), the silanol was then converted into SiO2in the BC matrix by pressingat 120◦C and 2 MPa. The BC/SiO2translucent sheets were examined by dynamic-mechanical analysis(DMA), thermo gravimetric analysis (TGA), and scanning electron microscopy (SEM). The temperaturedependence of the storage modulus, loss modulus and tan delta was determined by DMA. In general, theresults revealed that the increment of storage modulus and thermal stability increased concomitantlywith the augmentation of SiO2content. Therefore, it could be concluded that the mechanical propertiesof the composites were improved by using high amounts of nano silica. This would be a high aspectratio of BC capable of connecting the BC matrix and SiO2, thereby enhancing a large contact surface andresulting in excellent coherence. A decrease of the storage modulus was consistent with increasing tem-perature, resulting from softening of the composites. The storage modulus of the composites increasedin the order: BC/S7> BC/S5 > BC/S3, while the loss modulus and tan delta decreased. On the other hand,the thermal stabilities of all BC/SiO2composites were remarkably enhanced as compared to the pristineBC. TGA curves showed that the temperature of decomposition of the pure BC gradually shifted fromabout 260◦C to about 370◦C as silica content increased. SEM observations illustrated that the nano-scaleSiO2was embedded between the voids and nano-fibrils of the BC matrix. Overall, the results indicatedthat the successful synthesis and superior properties of BC/SiO2advocate its effectiveness for variousapplications.