Dynamic mechanical properties of bacterial cellulose nanofibres

In this work, dynamic mechanical properties of the grown bacterial cellulose (BC) nanofibers were investigated. BC pellicles were fabricated using bacterial fermentation (Gluconacetobacter xylinus). The morphology results confirmed that the dried BC at ambient conditions could be categorized as a xerogel. The thermal dynamic mechanical analysis results indicated that the bound water in bacterial cellulose structure had a very significant effect on thermal and dynamic mechanical properties of BC pellicles. The results of dehydration kinetics study showed that the main mechanism governing water loss of BC was Fickian diffusion. The glass transition temperatures (Tg) of the BC dried at 25 °C (ambient temperature) and 105 °C were estimated − 33 and − 18 °C, respectively. This discrepancy can be attributed to the plasticizing effect of the bound water of BC dried at ambient temperature. Furthermore, the results indicated that its modulus drop smaller than one order of magnitude can be attributed to its high crystalline nature. The storage modulus versus frequency increased due to the limitation of the relaxation process of the polymer chains. Moreover, the relaxation time distribution was achieved from the slope of the modulus master curve versus logarithmic frequency. As a result, BC exhibited a solid-like behavior.