Optimization of the isolation of nanocrystals from microcrystalline cellulose
by acid hydrolysis |
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Authors: | Daniel Bondeson Aji Mathew Kristiina Oksman |
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Institution: | (1) Department of Engineering Design and Materials, NTNU, Richard Birkelands vei 2b, Trondheim, N-7491, Norway |
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Abstract: | The objective of this work was to find a rapid, high-yield process to obtain an aqueous stable colloid suspension of cellulose
nanocrystals/whiskers. Large quantities are required since these whiskers are designed to be extruded into polymers in the
production of nano-biocomposites. Microcrystalline cellulose (MCC), derived from Norway spruce (Picea abies), was used as
the starting material. The processing parameters have been optimized by using response surface methodology. The factors that
varied during the process were the concentration of MCC and sulfuric acid, the hydrolysis time and temperature, and the ultrasonic
treatment time. Responses measured were the median size of the cellulose particles/whiskers and yield. The surface charge
as calculated from conductometric titration, microscopic examinations (optical and transmission electron microscopy), and
observation of birefringence were also investigated in order to determine the outcome (efficiency) of the process. With a
sulfuric acid concentration of 63.5% (w/w), it was possible to obtain cellulose nanocrystals/whiskers with a length between
200 and 400 nm and a width less than 10 nm in approximately 2 h with a yield of 30% (of initial weight). |
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Keywords: | Acid hydrolysis Cellulose nanocrystals Cellulose whiskers Optimization Response surface methodology |
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