Changes in Eucalyptus cellulose structure after different alkalization conditions

Abstract

Holocellulose samples isolated from Eucalyptus benthamii, E. nitens and E. smithii were treated with NaOH at different concentrations (up to 35%) and temperatures (25ºC and 80ºC), with the aim to determine their structural variations. X-ray diffraction analysis was used to determine crystallinity index (CrI), cellulose II (Cell-II) conversion, and crystallite size. Results showed an increase of CrI after 0.5% NaOH treatments and it was observed that Cell-II conversion started after 10% NaOH treatments at both temperatures, being lower the Cell-II content in E. benthamii and higher in E. nitens. Depending on the NaOH concentration, crystallite size varied, being observed an increase for cellulose I (Cell-I) crystal size from 3.5 to 5.0 nm, while Cell-II crystals were more homogeneous (4.7-5.1 nm). Significant cellulose structural differences were observed, which depended of the reaction conditions and cellulose source. This may be relevant in the processing and quality of cellulose derivatives. Acknowledgements: FONDECYT 1160306, CONICYT 21180299