Abstract:

The aim of this work was to analyze functionalized bacterial cellulose nanocrystals (BCNC) by XRD and other techniques, and to quantify the crystallinity index (CI) of the same. BCNC were obtained by H2SO4 (50% w/w) and HCl 36.5% (w/w) (1:1, v/v) hydrolysis (40 ºC, 2 hours, 1:100 w/v fibre:solution ratio). The nanostructures were carboxymethylated with NaOH and ClCH2COOH under two different reactional media: ethanol and isopropanol. The functionalized nanocrystals (FBCNC) were analyzed by XRD (Segal et al., 1959), as well as substitution degree (SD) and FTIR. The SD was higher for the samples from isopropanol (1.6) than for the samples from ethanol (1.1). The appearance of a new peak at 1600-1610 cm-1 in the FTIR spectra confirmed the carboxylation of BCNC. The CI of the FBCNC was 54.2% in ethanol and 26.9% in isopropanol, showing a reduction in comparison to the BCNC (89.3%), because of the substitution of cellulose hydroxyl for carboxymethyl groups. Thus, XRD was efficient for analyze the FBCNC.