Biomedical Engineering Reference
In-Depth Information
treated and bleached fiber, the decomposition temperature increases to 350°C in the
DTG curve of bleached fiber which corresponds to the thermal decomposition of cel-
lulose. The higher amount of residue in the raw kenaf fiber as compared to fiber after
alkali and bleaching treatment was due to the presence of ash as well as lignin (Ashori
et al., 2006).
The cellulose whiskers show significantly different degradation behavior. There
are two degradation stages in TGA curve starting from 198°C before the main peak
at 335°C. The lower temperature stage may corresponds to the degradation of more
accessible, and therefore more highly sulfated amorphous regions, whereas the higher
temperature stage is related to the breakdown of unsulfated crystal. In fact, the in-
troduction of sulfated groups into the crystals in the sulfuric acid hydrolysis process
could reduce the thermal stability of whiskers (Kim et al., 2001). On the other hand,
the increased weight residue of cellulose whiskers is because of the sulfate groups act-
ing as the flame retardants (Maren and William, 2004).
CoNClusioN
The study has been done to extract cellulose and to prepare cellulose nanowhiskers
from kenaf bast fiber. Results from morphological studies confirmed that the strong
effects of extraction method and a significant decrease in the size of fibers to na-
noscale. The FTIR results not only supported the results from FESEM analysis but
also revealed that the chemical structure of obtained cellulose nanowhiskers did not
change during hydrolysis process. Crystallinity was also increased by removal of the
amorphous part of fiber during cellulose extraction as well in cellulose nanowhiskers
by releasing individual cellulose crystals during hydrolysis process. Finally, thermo-
gravimetry analysis showed that thermal stability of fiber is also increased due to the
removal of lignin and hemicelluloses from raw fiber. However, the thermal stability
after hydrolysis is reduced due to the formation of sulfated group at surface of cellu-
lose which has low thermal degradation.
aCKNoWledGmeNt
Authors would like to acknowledge the financial support prepared by Ministry of
Higher Education (MOHE) under FRGS grant UKM-ST-07-FRGS0041-2009. We are
also like to thank Prof. Dr. Alain Dufresne and Gilberto Siqueiraat Grenoble Institute
of Technology, France for providing us with necessary equipment and for great discus-
sions in the research.
KeyWords
•
holocellulose
•
Kenaffiber
•
Nanowhiskers
•
Non-toxic
•
thermogravimetry
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