Chemically extracted nanocellulose from sisal fibres by a simple and industrially relevant process
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A novel type of acetylated cellulose nanofibre (CNF) was extracted successfully from sisal fibres using chemical methods. Initially, a strong alkali treatment was used to swell the fibres, followed by a bleaching step to remove the residual lignin and finally an acetylation step to reduce the impact of the intermolecular hydrogen bonds in the nanocellulose. The result of this sequence of up-scalable chemical treatments was a pulp consisting mainly of micro-sized fibres, which allowed simpler handling through filtration and purification steps and permitted the isolation of an intermediate product with a high solids content. An aqueous dispersion of CNF could be obtained directly from this intermediate pulp by simple magnetic stirring. As a proof of concept, the dispersion was used directly for preparing a highly translucent CNF film, illustrating that there are no large aggregates in the prepared CNF dispersion. Finally, CNF films with alkali extracts were also prepared, resulting in flatter films with an increased mass yield and improved mechanical strength.
KeywordsSisal fibres Cellulose nanofibres (CNFs) Cellulose films Acetylation Nanofibers
The author would like to acknowledge the FP7 - People - 2011, ITN Marie Curie International Training Network (ITN), COST Action FP1003 and COST Action FP1105 for financial support. Lars Schulte is acknowledged for his assistance with the microscopy analyses, Richard Andersson for carrying out the transmission electron microscopy and Sebastien Raynaud for assisting with measuring the optical properties of the composites with the Hazemeter.
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