Influence of dyestuffs on the crystallinity of a bacterial cellulose and a regenerated cellulose

Abstract

The crystal structures of bacterial cellulose (BC) obtained by cultivation of an Enterobacter species CJF 002 stock under the presence of direct, acid, and basic dyestuffs were examined. Optical microscopic observation showed that direct and basic dyestuffs stained BC samples but acid dyestuff did not. This suggests that direct and basic dyestuffs are contained within the resulting BC samples. Analysis of wide angle x-ray diffraction (WAXD) data indicates that direct dyestuffs inhibited crystallization of BC at dyestuff concentration in culture media (C_dye) of more than 0.05 wt% with lower angle shift of the diffraction peak for the (200) plane of BC, but almost no influence on BC crystallization in the case of basic dyestuff was observed. In addition, we investigated the crystallinity of regenerated cellulose (RC) from a cuprammonium solution and the reaction of RC with the dyestuffs. The dyestuffs had almost no impact on the crystallinity of RC even in cases where the samples showed staining. It was found that the apparent crystallite size of (110) and (020) in the RC samples with dyestuffs were slightly lower than that in the RC blank sample, while the apparent crystallite size of ( $1\overline{1}0$ ) in the RC samples with dyestuffs retain the values at the same level as the RC blank sample. These results suggest that the cellulose molecular sheets held together by van der Waals interactions were the basic structure formed from RC and they probably retain their structure in the cuprammonium solution at relatively high concentrations of cellulose.