INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Production of nanocellulose from natural fibres
Autor/es:
V. ALVAREZ; J. MORÁN; V. P. CYRAS; A. VÁZQUEZ
Lugar:
Montreal. Canada
Reunión:
Congreso; International Symposium on Bioplastics and Natural Fiber Composites.; 2006
Resumen:
The major fibres constituents of natural fibres are: a-cellulose, hemicellulose and lignin.  One possibility of the use of this kind of fibres is to produce products of higher values like nanocellulose fibres. There are two critical steps: the first one is to obtain the cellulose from natural fibres and the second one is to transform it on nanofibres. In this work (Brascorda, Brazil), sisal fibres were used. For the first step, two different procedures were used:  a) The holocellulose (a-cellulose + hemicellulose) was obtained by the gradual removal of lignin by treating dewaxed fibres with 0.7% sodium chlorite at pH 4 at the boil for 2 h using a fibre to liquor ratio of 1:50. It was then treated with sodium bisulphite solution, followed by filtering, washing and drying at 100ºC till constant weight was reached; a-cellulose was obtained by treating holocellulose with 17.5% NaOH solution b) A pre-treatment with 0.1 M NaOH in 50 % ethanol at 45 ºC for 3 h. under continuous agitation. This stage was followed by several treatments with H2O2 at pH=11.5 (buffer solution) and 45 ºC: 0.5 % H2O2; 1.0 % H2O2; 2.0 % H2O2 and 3.0 % H2O2 for 3 h. with continuous agitation. After filtration fibres were treated with 10 % NaOH – 1 % Na2B4O7·10 H2O at 28 ºC for 15 h., continuous agitation. Several washing with ethanol were carried out in order to wash the obtained cellulose. Although the second treatment is larger, it is also more environmental friendly.                 The nanofibres were prepared by the acid hydrolysis (sulphuric acid at 45ºC, 30 min under continuous stirring) of obtained celluloses.   Composition was determined by FTIR (for chemical characterization) and TGA (for determining the cellulose, hemicelluloses and lignin content) in each step. SEM and AFM were used in order to determine the dimensions of the fibres. The nanofibres will be used as reinforcement on biodegradable matrices (PCL – MaterBi) in order to produce bionanocomposites. Mechanical properties will be studied.