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Preparation and Characterization on Cellulose Nanofiber Film

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Materials Science Forum
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Li Yuan Zhang
Li Yuan Zhang
Li Yuan Zhang
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T. Tsuzuki at Australian National University
T. Tsuzuki
Xun Gai Wang
Xun Gai Wang
Xun Gai Wang
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Abstract and Figures

In this study, cellulose nanofibers were obtained from wood pulp using a chemo-mechanical method and thin films were made of these cellulose nanofibers. The morphology of the films was studied by scanning electron microscopy (SEM). SEM image analysis revealed that the films were composed of cellulose nanofibers with an average diameter of around 32 nm. Other properties were also characterized, including the degree of crystallinity by X-ray diffraction, chemical bonding by infrared attenuated total reflectance analysis, and thermal properties by differential scanning calorimetry. The foldable, strong, and optically translucent cellulose nanofiber films thus obtained have many potential applications as micro/nano electronic devices, biosensors and filtration media, etc.
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Preparation and Characterization on Cellulose Nanofiber Film
Liyuan Zhang
1, a
, Takuya Tsuzuki
1, b
and Xungai Wang
1, c
1
Centre for Material and Fibre Innovation, Institute for Technology Research and Innovation,
Deakin University, Geelong, Victoria 3217, Australia
a
lzh@deakin.edu.au,
b
takuya.tsuzuki@deakin.edu.au,
c
xungai.wang@deakin.edu.au
Keywords: Cellulose, nanofiber, ball milling
Abstract. In this study, cellulose nanofibers were obtained from wood pulp using a
chemo-mechanical method and thin films were made of these cellulose nanofibers. The morphology
of the films was studied by scanning electron microscopy (SEM). SEM image analysis revealed that
the films were composed of cellulose nanofibers with an average diameter of around 32 nm. Other
properties were also characterized, including the degree of crystallinity by X-ray diffraction, chemical
bonding by infrared attenuated total reflectance analysis, and thermal properties by differential
scanning calorimetry. The foldable, strong, and optically translucent cellulose nanofiber films thus
obtained have many potential applications as micro/nano electronic devices, biosensors and filtration
media, etc.
Introduction
Sustainable development, reducing pressure on fossil fuel demand and waste reduction are
interrelated factors and are essential to the future of our society. Nanotechnology creates
“miniaturized” systems to achieve these goals though facilitating the manufacturing of novel
materials that are lighter, smaller and of higher performance. One of the examples is cellulose
nanofibers with diameters below 100 nm. Cellulose nanofibers have many outstanding properties
such as a very large surface-to-volume ratio, a high Young’s modulus, high strength, high
transparency and a very low coefficient of thermal expansion (CTE) [1, 2]. As such, cellulose
nanofibers find many applications in high-strength nanocomposite [3-5], optical nanocomposite [6],
optically transparent papers for electronic devices [2], biosensors and filtration media [7, 8].
Cellulose is one of the renewable raw materials and is the most abundant organic polymer on
earth. There are many methods to produce cellulose nanofibers from the woody raw materials.
Electrospinning [9] gives good quality output but low production efficiency. Electrospray [10]
normally results in poorer quality fibers. Biosynthesis [11] offers excellent quality fibers but suffers
from high costs and safety risks. Cryocrushing techniques [12] require costly multi-step processes. In
order to overcome the shortcomings of those methods, more economical and efficient techniques need
to be developed. Recently Yano’s group reported a very simple mechanical method that involves a
grinding process after solvent extraction and chemical treatment of wood powders [1]. Here we report
the production of thin films by using cellulose nanofibers which are prepared by another efficient
method from wood pulp by ball milling.
Experimental Procedures
Cellulose anofibers. Dried soft-wood pulp (NIST standard material RM 8495 Northern Softwood
Bleached Kraft Pulp) was used as a raw material. The dried pulp was first treated in water at room
temperature to loosen the strong hydrogen bonding between original fibers. The loosened fibers were
subjected to ball milling in water using a Spex 8000M shaker mill. The fibers were milled for various
durations. In a typical run, 25 g of 1 wt% pulp suspension in water was milled using cerium-doped
zirconia grinding balls with diameters between 0.1 and 1 mm for 2 hours. The weight ratio between
the grinding balls and original fibers was 50 : 1.
Materials Science Forum Vols. 654-656 (2010) pp 1760-1763
© (2010) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/MSF.654-656.1760
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of the
publisher: Trans Tech Publications Ltd, Switzerland, www.ttp.net. (ID: 128.184.132.38-28/06/10,06:42:44)
Cellulose anofiber Film. An aqueous suspension of cellulose nanofibers with the
concentration of 0.2 wt% was made and stirred overnight. 200 g of the suspension was filtered for 3
hours and poured into a container made of an aluminum film. The suspension was dried in the oven at
80 ºC for 6 hours. A translucent film was obtained after removing the film from the aluminum film
container.
Characterization. The morphology of original and milled cellulose fibers was studied by
scanning electron microscopy using a Zeiss Supra 55VP. The nature of chemical bonding was
analysed by Fourier-transform infrared (FT-IR) measurements in reflectance mode, using a Bruker
FTIR Spectrophotometer. The degree of crystallinity was assessed by X-ray diffractometry (XRD)
using a Philips PW1729 X-ray powder diffractometer. Thermo gravimetric (TG ) analysis was
conducted to determine the thermal decomposition temperature, using a Netzsce 409CCluxx
analyzer.
Results and Discussion
A typical SEM image of the loose raw cellulose fibers is shown in Fig. 1. The fibers appear to have
rather flat shapes. SEM images of the samples milled for 2 hours are shown in Figs. 2 and 3 at
different magnifications. It is evident that the fibers were milled into rather uniform morphology and
most of the nanofibers had diameters smaller than 100 nm. SEM image analysis using Image-Pro
Plus software revealed that the fiber diameter decreased rapidly from 38 µm to 32 nm within 2 hours
of milling (Table 1). The fiber diameter distribution showed a narrow log-normal model as shown in
Fig. 4.
Figure 1 SEM image of cellulose fibers before
milling.
Figure 2 SEM image of cellulose fibers after milling
(at low magnification).
Figure 3 SEM image of cellulose fibers after
milling (at high magnification).
Figure 4 Distribution of fiber diameter after milling.
Materials Science Forum Vols. 654-656 1761
Figure 5 shows the infrared absorbance spectra of cellulose nanofiber films calculated from the
attenuated total reflectance (ATR). The spectra of the 100% crystalline cellulose (purchased from
Sigma Aldrich) are also shown in Fig. 5 for comparison. The peak at 2853 cm
-1
indicates that the CH
2
asymmetric stretching vibration [13] has been strengthened in the cellulose nanofiber film.
XRD spectra of the cellulose nanofiber films were evaluated for
crystallinity
. As can be seen in
Fig. 6, the sample retained good crystallinity in the cellulose I structure, even after milling for 2 hours
[14].
TG curves in Fig. 7 showed that the cellulose nanofiber film decomposed at 304 °C which is
closed to the decomposition temperature of raw cellulose fibers. This indicates that the cellulose
nanofiber film has thermal stability similar to that of the raw cellulose fibers.
Summary
In this work, a simple method of producing cellulose nanofiber films was demonstrated. The average
diameter of the fibers was about 32 nm and most of the nanofibers had diameters smaller than 100 nm.
The fiber diameter showed a narrow log-normal distribution. This method enables the production of
cellulose nanofiber films from sustainable resources without hazardous organic solvent in a very
efficient manner, which may realize many environmentally friendly applications such as
biodegradable and biocompatible nanocomposites and biosensors.
Figure 7. TG curves of cellulose nanofiber films
Figure 6. XRD spectrum of cellulose nanofiber films
Table 1. Fiber diameter distribution, analysed on SEM images
Sample
Fiber Diameter
Mean
D(0.5)
D(0.9)
Fiber before milling, [µm]
38 35 43
Fiber after milling, [nm]
32 25 45
Figure 5.
ATR of cellulose nanofiber film
.
1762 PRICM7
Acknowledgment
Authors appreciate IDP Student Mobility Scholarship for the support from IDP Education Australia
Ltd.
References
[1] K.Abe, S. Iwamoto, and H. Yano, Biomacromolecules, 2007. 8(10), pp.3276-8.
[2] M.Nogi, S. Iwamoto, A.N.Nakagaito, and H. Yano, 2009. 21(16), pp.1595-1598.
[3] H.Yano , Research Journal of Food and Agriculture (Japan), 2005. 28(10), pp.20-24.
[4] A.Iwatake, M. Nogi, and H. Yano, Composites Science and Technology, 2008. 68(9),
pp.2103-2106.
[5] A.Bhatnagar, and M. Sain, Journal of Reinforced Plastics and Composites, 2005. 24(12),
pp.1259-1268.
[6] Y.Okahisa, A.Yoshida, S.Miyaguchi, H.Yano, Composites Science and Technology, 2009.
69(11-12), pp.1958-1961.
[7] M.A.Hubbe, O.J.Rojas, L.A.Lucia, and M.Sain, BioResources, 2008. 3(3), pp.929-980
[8] L.Zhang, T.J. Menkhaus, and H. Fong, Journal of Membrane Science, 2008. 319(1-2),
pp.176-184.
[9] P. Kulpinski, Journal of Applied Polymer Science, 2005. 98(4), pp.1855-1859.
[10] X.Sui, J.Yuan, W.Yuan, and M.Zhou, Chemistry Letters, 2008. 37(1), pp.114-115.
[11] S.Hesse, and T. Kondo, Carbohydrate Polymers, 2005. 60(4), pp.457-465.
[12] A.Alemdar, and M. Sain,. Bioresource Technology, 2008.99, pp.1664-1671.
[13] F.Carrillo, X. Colom, J.J. Suñol, and J.Saurina. European Polymer Journal, 2004.40(9),
pp.2229-2234.
[14] M.L.Nelson and R.T.O'Connor, Journal of Applied Polymer Science, 1964.8(3), pp.1325-1341.
Materials Science Forum Vols. 654-656 1763
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  • Jun 2005
  • CARBOHYD POLYM
Acetobacter xylinum NQ-5 (ATCC 53582) and AY-201 (ATCC 23769) cultivated in the Hestrin–Schramm medium containing d-glucose with a natural 13C-abundance of 1.1% were investigated regarding their cell division rates and the bacterial movements. Comparative studies were carried out in the presence of d-glucose-U-13C6 with a uniform 13C-labeling of 99% as the sole carbon source. The bacterial growth rates in numbers were found to increase in the 13C-enriched media by about 13% for NQ-5 and 26% for AY-201, respectively. The movements of single cells caused by the inverse force of the secretion and deposition of cellulose nanofibers on nematic ordered cellulose (NOC) templates were investigated by real-time video analyzes using light microscopy. As a result, d-glucose-U-13C6 reduced the speed of motion for both strains, which was an opposite trend to the above growth rates in the cell division. The deposited cellulose fibers were proved to be in a cellulose crystalline form by CP/MAS 13C NMR and NIR FT Raman spectroscopic measurements, although the biosynthesized and thereafter-deposited cellulose has a strong interaction with the surface of NOC.
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