Effect of post-synthetic processing conditions on structural variations and applications of bacterial cellulose

Physicochemical properties of materials can be amended by altering their physical structure through different processing conditions. The present study was conducted to investigate the post-synthesis structural variations and physico-mechanical properties of bacterial cellulose (BC) sheets prepared using different drying methods. Wet BC sheets of the same origin were freeze dried (BC-FD), dried at room temperature (25 °C) (BC-DRT), and dried at elevated temperature (50 °C) (BC-DHT). FE-SEM micrographs revealed that BC-DRT and BC-DHT had a more tightly packed and compact structure than the loosely held fibrils of BC-FD. XRD analysis revealed the relative crystallinity of the BC sample to be 64.60, 59.16, and 47.20 % for BC-DHT, BC-DRT and BC-FD, respectively. The water holding capacity (WHC) of the BC-FD was higher than that of the other two samples. Four consecutive drying and rewetting cycles demonstrated that the WHC of all samples decreased with each cycle. The WHC of BC-DRT and BC-DHT was reduced to almost 0 after the first drying cycle, but the BC-FD samples were able to regain some of their WHC. The tensile strength and elongation modulus were in the order of BC-DHT > BC-DRT > BC-FD. Overall, the results of this study revealed that the post-synthetic processing conditions had a strong effect on the structure and physico-mechanical properties of BC.