ArticlePDF Available

X-ray diffraction study of bamboo fibers treated with NaOH

Authors:
Yanping Liu at Donghua University
Yanping Liu
Hong Hu at The Hong Kong Polytechnic University
Hong Hu
Download full-text PDF
Read full-text
Download citation

Abstract

Bamboo fibers are a new kind of natural materials which have a big potential application in textile field due to some of their particular properties. However, high crystallinity and orientation structure can result in some undesirable properties and this will limit their further applications as textile materials. As a common used way, mercerization was adapted to treat bamboo fibers in this work in order to improve their undesirable properties. X-ray diffraction (XRD) was used to characterize their microstructure after treatment with NaOH. The amount of cellulose II and the crystallinity index based on the XRD results were calculated for the evaluation of the effectiveness of the different treatment conditions, such as alkali concentration, mercerization duration and temperature, as well as tension applied to the fibers during mercerization, on the transformation degree of cellulose I to cellulose II and decrystallization of the mercerized bamboo fibers. It has been found that each condition has different effects and that the greatest effectiveness of crystal lattice conversion and decrystallization could be achieved with such mercerization condition: 16 % alkali concentration, 10 minutes of mercerization at 20 °C without tension applied to the fibers.
Content uploaded by Hong Hu
Author content
All content in this area was uploaded by Hong Hu on Jul 04, 2014
Content may be subject to copyright.
Fibers and Polymers 2008, Vol.9, No.6, 735-739
735
X-ray Diffraction Study of Bamboo Fibers Treated with NaOH
Yanping Liu1 and Hong Hu*
Institute of Textile & Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
1College of Textiles, Donghua University, Shanghai 201620, P. R. China
(Received June 14, 2008; Revised September 19, 2008; Accepted October 9, 2008)
Abstract: Bamboo fibers are a new kind of natural materials which have a big potential application in textile field due to
some of their particular properties. However, high crystallinity and orientation structure can result in some undesirable prop-
erties and this will limit their further applications as textile materials. As a common used way, mercerization was adapted to
treat bamboo fibers in this work in order to improve their undesirable properties. X-ray diffraction (XRD) was used to charac-
terize their microstructure after treatment with NaOH. The amount of cellulose II and the crystallinity index based on the
XRD results were calculated for the evaluation of the effectiveness of the different treatment conditions, such as alkali con-
centration, mercerization duration and temperature, as well as tension applied to the fibers during mercerization, on the trans-
formation degree of cellulose I to cellulose II and decrystallization of the mercerized bamboo fibers. It has been found that
each condition has different effects and that the greatest effectiveness of crystal lattice conversion and decrystallization could
be achieved with such mercerization condition: 16 % alkali concentration, 10 minutes of mercerization at 20 oC without ten-
sion applied to the fibers.
Keywords: Mercerization, Bamboo fiber, Cellulose, Sodium hydroxide, X-ray diffraction, Crystallinity
Introduction
Bamboo fiber’s unique structure makes it superior over
other natural lignocellulosic fibers [1]. In recent years,
bamboo fibers have attracted great attention as the most
abundant renewable biomass materials which can be used in
textile [2] and composite reinforcement [3-7]. Bamboo
fibers possess many excellent properties when used as textile
materials such as high tenacity, excellent thermal conductivity,
resistant to bacteria, and high water and perspiration
adsorption. However, the special molecular structure of
bamboo fibers due to high crystallinity and orientation
results in some undesirable properties, such as bad elasticity,
poor wrinkle recovery, harsh handle, low dyeability and
itching when worn next to the skin for the fabrics made of
them [2]. Ameliorating these undesirable properties by
mercerization process has been considered as a common
used way [8-12]. The mercerization can produce the twisting
and shrinking effects on the fibers and make them softer due
to intra-crystalline swelling and crystallographic cell’s
modification from native cellulose I to cellulose II. The
effectiveness of the mercerization process depends on the
degree of crystal lattice conversion and decrystallization.
Over the past several years, considerable work has been
done for the lignocellulosic fibers such as ramie [9], jute
[10], flax [9,11] and wood [12] to ameliorate their undesirable
properties through mercerization process. However, very
little work has been done for the bamboos. While normal
bamboo strips only include 60 % of the cellulose [13],
bamboo fibers for textile utilization will content more than
90 % of the cellulose. Thus, the required treatment conditions
and effects would be different in these two cases. Although
Mahuya Das et al. [3-7] reported their investigations on the
treatment of bamboo strips with NaOH solutions at different
concentration (from 2 to 50 %) and found that during alkali
treatment, a lattice transformation from cellulose I to
cellulose II took place, there is very little literature that
focuses on the mercerization of bamboo fibers.
This paper will present a study on the mercerization of
bamboo fibers. Effective mercerization requires attention to
variable conditions such as alkali concentration, treatment
temperature and duration as well as tension applied to the
bamboo fibers during the treatment [14]. For this reason, the
effects of these conditions on the degree of transformation
from cellulose I to cellulose II and decrystallization of the
mercerized bamboo fibers will be analyzed. The amount of
cellulose II and the crystallinity index based on the X-ray
diffraction (XRD) method will be used to evaluate effects of
each treatment.
Experimental
Materials
Bamboo fibers with a fineness of 6.0 dtex and cellulose
content of about 97 % were used. They were directly
extracted from bamboo stem by mechanical method and
enzymatic degumming process. All the bamboo fiber
samples were provided by Xuesong Co. Ltd., Hunan, China.
Alkali Treatment
Alkali treatments were carried out under different
conditions in order to investigate their effects.
For investigating the effects of alkali concentration, the
fibers were treated with NaOH solutions at varied
concentrations by weight from 4 to 24 % for 20 min at 20 oC.
For investigating the effects of mercerization duration,
*Corresponding author: tchuhong@polyu.edu.hk
736 Fibers and Polymers 2008, Vol.9, No.6 Yanping Liu and Hong Hu
NaOH solutions of four different concentrations (10 %,
12 %, 16 %, and 25 %) were selected. For each concentration,
the fibers were treated for 1, 2, 3, 4, 5, 7.5, 10, 20, and 30
min at 20 oC.
For investigating the effects of mercerization temperature,
NaOH solutions of four different concentrations (10 %,
12 %, 16 %, and 25 %) were adapted as well. For each
concentration, the fibers were treated at 2, 10, 20, 30, 40, and
50 oC for 20 minutes.
For investigating the effects of tension applied to the fibers
during mercerization, a bamboo yarn of 18.2 Tex was used.
The yarn hanks were fixed on a steel frame with an
adjustable length in order to restrict yarn shrinkage and to
control tension. As the bamboo yarn had a shrinkage of
about 33 % when mercerized under zero tension, five
tension levels were selected, i.e., the yarn mercerized with
zero shrinkage denoted as 100 % tension mercerization
(100 % T-M), 10 % shrinkage as 90 % T-M, 20 % shrinkage
as 80 % T-M, 30 % shrinkage as 70 % T-M, and maximum
shrinkage as slack mercerization (S-M). The yarn fixed on
the frame was then dipped into a 16 % NaOH solution at
20 oC for 20 minutes.
The ratio of material/liquid by weight was 1: 50 for all the
treatments. After the alkali treatments, all the samples were
rinsed with distilled water, neutralized with 2 % acetic acid,
finally rinsed again with distilled water until neutral and
dried in the air (20±1 oC, 65±2 % RH).
Structural Investigations
X-ray diffraction (XRD) was used to investigate the
supermolecular structure of bamboo fiber cellulose after
different treatments. X-ray diffraction data were obtained
using a Rigaku Ultima3 X-ray instrument and the samples
were prepared by powder. Ni-filtered CuK
α
radiation
(
λ
=1.54060 Å) generated at a voltage of 40 kV and current
of 40 mA was utilized, and a scan speed of 5 o/min from 2
θ
5o to 45 o was used.
To calculate the amount of cellulose II and the crystallinity
index, MDI Jade Version 7.0 software was applied to
separate the background and the overlapped peaks. After the
separation of X-ray diffraction lines, the amount of cellulose
II was calculated on the basis of the separated area under the
peaks of cellulose I and cellulose II [11,12]. The crystallinity
index was determined by comparing the areas under
crystalline peaks and the amorphous curve [11,12].
Results and Discussion
The Effects of Alkali Concentration
The XRD patterns of the bamboo fibers treated with
various NaOH concentrations are shown in Figure 1. It can
be found that the pattern of the control bamboo fibers
exhibits a sharp high peak at 2
θ
22.7 o and two overlapped
weaker diffraction peaks respectively at 2
θ
15 o and 16.3 o,
which are assigned to cellulose I. Bamboo fibers treated with
4~11 % NaOH solutions display similar diffraction patterns
as that of the control. However, when the NaOH concen-
tration is changed to 12 %, two additional diffraction peaks
appear at 12.2 o and 20.1 o, which are assigned to cellulose
II. The bamboo fibers treated with 16 to 24 % NaOH
solutions show typical diffraction patterns of cellulose II.
The calculated crystallinity index and the amount of
cellulose II of the bamboo fibers after treatment are
presented in Figure 2. It can be found that the crystallinity
index slightly increases by about 2.5 % when the NaOH
concentration increases from 4 % to 10 %. However, from
11 % NaOH concentration, the crystallinity index starts to
fall down sharply and gets its minimum value (57.8 %) at
16 % NaOH concentration. After then, the crystallinity index
slightly increases again until 18 % NaOH concentration, and
then keeps constant. The variation of the amount of cellulose
II is just the inverse as that of the crystallinity index. The
calculated results show that the transformation of cellulose I
to cellulose II starts from 12 % NaOH concentration, and that
Figure 1. X-ray diffraction patterns of the bamboo fibers treate
d
with various concentrations of NaOH (20 oC, 20 min).
Figure 2. Amount of cellulose II and crystallinity index of bamboo
fibers vs. NaOH concentration (20 oC, 20 min).
X-ray Diffraction Study of Bamboo Fibers Treated with NaOH Fibers and Polymers 2008, Vol.9, No.6 737
the greatest efficiency of polymorphic transition of cellulose
is obtained at 16 % NaOH concentration. It is necessary to
point out that the transformation of cellulose I to cellulose II
can only be accomplished when the NaOH concentration is
at 16 % or above, but the transformation can not be complete.
This result agrees with that suggested by Warwicker [15].
These phenomena can be explained as follows. It is well
known that the cellulosic fibers have three distinct processes
during mercerization: fiber swelling, disruption of the
crystalline areas and formation of new crystalline lattice
after rinsing away mercerizing solution. At lower concentra-
tions, the hydroxide ions could be fully hydrated and they
may not be able to penetrate and disrupt the cellulose lattice
due to size restriction [16]. Only the amorphous regions and
crystal surfaces in the cellulose structure, that is, the
cementing materials, can react with alkali and be removed.
Thus, the interfibrillar regions are likely to be less dense and
less rigid and thereby make the fibrils more capable of
rearranging by themselves [17]. Consequently, the crystallinity
index of fibers increases at lower NaOH concentration.
However, as the NaOH concentration increases, the amount
of free water available for hydrating the hydroxide ions
would be diminished. In this case, the dehydrated hydroxide
ions get smaller and can more easily penetrate the lattice.
With continuous increase of the NaOH concentration, the
crystalline structure of the cellulose gets be swelled and
relaxed, and when the most swollen state reaches, the
hydrated hydroxide ions penetrate the inside of the crystal,
and undergo a thorough reaction with the cellulose. At the
same time, the viscosity of the NaOH solution increases with
increase of the concentration, so that the penetration of the
hydrated hydroxide ions is hindered. According to the above
calculated result, the NaOH concentration at 16 % is
appropriate for crystal lattice transformation and decrystalli-
zation of bamboo fibers.
The Effects of Mercerization Duration
The amount of cellulose II as a function of mercerization
duration for various NaOH concentrations is shown in
Figure 3. It can be found that the variations of the amount of
cellulose II for different mercerization duration depend on
the NaOH concentration. For the bamboo fibers treated with
10 % NaOH solution, the amount of cellulose II is not
changed. However, for the bamboo fibers treated with 12 %
and 16 % NaOH solutions, an obvious increase of the
amount of cellulose II at the beginning of treatment is
observed and their stabilized state reaches after about 5
minutes of treatment. It is necessary to notice that the
mercerization with 25 % NaOH solution causes a rapid
decrease of the amount of cellulose II after 3 minutes of
treatment. S. Borysiak et al. [11] also got the similar result in
mercerization of flax. The reason for this situation may be
the formation of Na-cellulose III which could not be
transformed into cellulose II. Okano et al. [18] suggested
that the stage of Na-cellulose I formation is an irreversible
step of mercerization. However, Hayashi et al. [19] demon-
strated that Na-cellulose I contains two coexisting phases
Na-cellulose II (which regenerates cellulose I) and Na-
cellulose III (which regenerates cellulose II). Later, Kim et al.
[20] observed the regeneration from Na-cellulose I into
cellulose I. The result of this study confirms this reconversion.
Figure 4 shows the variations of the crystallinity index in
function of mercerization duration. It can be observed that
the variation trends of the crystallinity index are just the
inverse of the amount of cellulose II and the same
explanation can be made as above.
The Effects of Mercerization Temperature
The calculated amount of cellulose II and crystallinity
index of the fibers mercerized at different temperature are
presented in Figures 5 and 6, respectively. It is found from
Figure 5 that the amount of cellulose II increases with
Figure 3. Amount of cellulose II of bamboo fibers vs. merceriza-
tion duration (20 oC).
Figure 4. Crystallinity index of bamboo fibers vs. mercerization
duration (20 oC).
738 Fibers and Polymers 2008, Vol.9, No.6 Yanping Liu and Hong Hu
decrease of mercerization temperature. For the fibers treated
with 12 % NaOH solution, the transformation accomplishes
when the temperature is reduced to 2 oC, and for the fibers
treated with 10 % NaOH solution, about 55 % cellulose II is
obtained at 2 oC. For the fibers treated with 16 % NaOH
solution, the polymorphic conversion of cellulose can not
accomplish at above 30 oC. For the bamboo fibers treated
with 25 % NaOH solution, no effect of temperature on the
transformation of cellulose I to cellulose II is observed.
Figure 6 just shows that the variations of the crystallinity
index of mercerized bamboo fibers are just the inverse as
those of the amount of cellulose II.
The above phenomena can be explained by the fact that
the size of hydrated hydroxide ions would increase as the
treatment temperature increases. Thus, the increase of the
treatment temperature reduces the absorption of the alkali,
so that the effectiveness of the mercerization reduces.
Furthermore, the increase of NaOH concentration to decrease
the size of hydrated hydroxide ions could counteract the
reduced absorption and achieve the same effect from the
mercerization. On the other hand, low treatment temperature
reduces the NaOH concentration which is needed for the
thorough transformation of cellulose lattice.
The Effects of Applied Tension During Mercerization
The results of the peak resolution of the bamboo fibers
mercerized at different tensions are shown in Figure 7,
which clearly shows the effect of tension on the
transformation of cellulose I to cellulose II. It can be found
that the ratio of conversion increases with decrease of the
tension as the crystallinity index of the mercerized bamboo
fibers also reduces with decrease of tension. This is due to
the fact that higher tension during mercerization could cause
a significant decrease of the fiber swelling degree.
Conclusion
According to the above analysis, the following results can
be obtained;
1. The NaOH concentration over 11 % has considerable
effects on the transformation of cellulose I to cellulose II
at room temperature. Inversely, the NaOH concentration
under 11 % results in a slight increase of the crystallinity
index. The greatest efficiency of polymorphic transition of
cellulose is obtained at 16 % NaOH concentration. The
NaOH concentration above 16 % no longer increases the
effects of transformation of cellulose I to II. For all the
NaOH concentrations used, the transformation can not be
complete even the bamboo fibers are deeply mercerized.
2. The effects of the treatment duration on the transformation of
cellulose I to cellulose II depend on the NaOH concen-
tration. For the 10 % NaOH concentration, no effect of
treatment duration is observed. However, for the NaOH
concentration respectively at 12 % and 16 %, the obvious
Figure 5. Amount of cellulose II of bamboo fibers vs. merceriza-
tion temperature (20 min).
Figure 6. Crystallinity index of bamboo fibers vs. mercerization
temperature (20 min).
Figure 7. Amount of cellulose II and crystallinity index of bamboo
fibers vs. applied tension during mercerization (16 % NaOH,
20 oC, 20 min).
X-ray Diffraction Study of Bamboo Fibers Treated with NaOH Fibers and Polymers 2008, Vol.9, No.6 739
effects are noticed at the beginning of 5 minutes. The
greatest effectiveness of crystal lattice conversion is
reached during the first 10 minutes of mercerization, and
then the increases of treatment duration no longer increase
the treatment effects. The treatment with 25 % NaOH
solution causes the reverse effect after 3 minutes.
3. The effects of the treatment temperature on the
transformation of cellulose I to cellulose II equally depend
on the NaOH concentration. The effects of the transformation
decrease with increase of the treatment temperature
except for the concentration of NaOH at 25 %, where no
effect is observed. The increase of the NaOH concentration
could counteract the reduced absorption and achieve the
same effect from the mercerization.
4. The effects of the tension applied to fibers during the
treatment are evident. The ratio of transformation of
cellulose I to cellulose II increases with decrease of the
tension. For getting better effect of the transformation,
low tension should be applied.
References
1. A. K. Ray, S. K. Das, S. Mondal, and P. Ramachandrarao,
J. Mater. Sci., 39, 1055 (2004).
2. X. Y. Xu, Y. P. Wang, X. D. Zhang, G. Y. Jing, D. P. Yu,
and S. G. Wang, Surf. Interface Anal., 38, 1211 (2006).
3. M. Das, A. Pal, and D. Chakraborty, J. Appl. Polym. Sci.,
100, 238 (2006).
4. M. Das and D. Chakraborty, J. Appl. Polym. Sci., 102,
5050 (2006).
5. M. Das and D. Chakraborty, Polym. Compos., 28, 57
(2007).
6. M. Das and D. Chakraborty, Ind. Eng. Chem. Res., 45,
6489 (2006).
7. M. Das and D. Chakraborty, J. Appl. Polym. Sci., 107, 522
(2008).
8. J. Mercer, Br. Patent, 13296 (1850).
9. L. Cheek and L. Roussel, Tex t . R es. J . , 59, 478 (1989).
10. R. R. Mukherjee and H. J. Woods, Nature, 165, 818 (1950).
11. S. Borysiak and J. Garbarczyk, Fibres & Textiles in East.
Eur., 11 , 104 (2003).
12. S. Borysiak and B. Doczekalska, Fibres & Textiles in East.
Eur., 13, 87 (2005).
13. K. Okubo, T. Fujii, and Y. Yamamoto, Composites Part A,
35, 377 (2004).
14. S. I. Kim, E. S. Lee, and H. S. Yoon, Fiber. Polym., 7, 186
(2006).
15. J. O. Warwicker, J. Polym. Sci., Polym. Chem., 5, 2579
(1967).
16. M. H. Lee, H. S. Park, K. J. Yoon, and P. J. Hauser, Text .
Res. J., 74, 146 (2004).
17. J. Gassan and A. K. Bledzki, Compos. Sci. Technol., 59,
1303 (1999).
18. T. Okano and A. Sarko, J. Appl. Polym. Sci., 30, 325
(1985).
19. J. Hayashi, T. Yamada, and K. Kimura, Appl. Polym. Symp.,
28, 713 (1976).
20. N. H. Kim, J. Sugiyama, and T. Okano, Mokuzai Gakkaishi,
36, 120 (1990).
... pattern revealed the appearance of two additional peaks, at 2h ¼ 12.1 � and 20.3 � , associated with typical cellulose II. [52] The crystallinity index, crystallite size, and D spacings for the samples are summarized in Table 2; it can be seen that the CrI for the natural fibers was 49.4%. Compared with other natural fibers, Spart has a higher CrI than that found in Date palm (38.5%) and Coconut (41.9%). ...
... [53] As a consequence, the samples treated with 8% and 10% NaOH contained more crystalline cellulose and the degree of crystallinity increased. [18,47,48,[50][51][52][53][54] These results were well supported by the FTIR analysis. For concentrations beyond 10% NaOH, CrI notably decreases until reaching 53.4% at higher concentrations and the size of the hydrate ions decreases due to the absence of water molecules for hydration of the hydroxide ions. ...
View
... With the continuous rise in NaOH concentration, the crystalline structure of the cellulose expands and relaxes. When the cellulose reaches its most swollen state, the hydrated hydroxide ions can permeate crystal's interior, engaging in an extensive reaction with the cellulose molecules (Liu and Hu, 2008), and then damage the H-bonds. In the reactive dyeing of cellulosic ramie fibre, the reactive dye molecules only existed in the amorphous region, and they were impossible to migrate inside the crystalline region. ...
... However, at room temperature, the high viscosity (Lee et al., 2004) of a strong caustic solution impedes NaOH transfer inside the crystallinity of cellulosic fibre, because the viscosity of the alkaline solution mainly depends on the intermolecular interactions between ions and the hydration of the ions. At high temperatures, the viscosity of the NaOH solution decreases (Liu and Hu, 2008), because when the temperature increases, the intermolecular spacing between liquid molecules increases, leading to a decrease in intermolecular attraction and thereby reducing the internal friction and the NaOH easily migrates inside the fibre, offering a different performance from normal mercerization, especially for yarn or fabric. Thus, for alkaline pre-treating of ramie fibre, the temperature of NaOH was varied from 25 to 80 • C, and the treating time of ramie fibre in NaOH solution (140 g/L) and in iso-butanol solvent was fixed at 1 hr, subsequent dyeings of AIBF@140 g/L were carried out. ...
Improving the dyeability of ramie fibre by sequential alkaline and alcohol pretreatments
Article
  • Jun 2024
  • IND CROP PROD
The high crystallinity of ramie fibre poses challenges in achieving optimal dyeing performance, such as reduced dye exhaustion. To enhance the dyeing capabilities of ramie fibre, several alterations were experimented with, such as caustic mercerization using a NaOH solution. However, because of the high NaOH concentration, removing the NaOH residue from inside the fibre becomes challenging. Herein, the present research aims to enhance the dyeing efficiency of ramie fibre by using sequential alkaline and alcohol pretreatment methods to reduce NaOH usage, accordingly relieving the wash process stress. The preliminary screening findings have revealed that iso-butanol is the most suitable alcohol solvent for modifying ramie fibres after treating it with NaOH solution since it leads to higher dye exhaustion (E%, 95.7%), dye fixation rate (F%, 88.2%), total dye fixation efficiency (T%, 84.4%), and K/S values (41.4). After that, the orthogonal array experimental scheme (L16) was applied to optimize dyeing performance. The NaOH usage was decreased to 160 g/L, the treating time was reduced to 3 min, and the dyeing performance of ramie fibre treated under the optimum conditions was better than that of a caustically mercerized one. It was determined that the NaOH concentration factor had the most contribution, accounting for 75.34% of the observed effects. The NaOH solution temperature factor followed closely behind, contributing 22.69%. Additionally, using analytical methods such as XRD, FTIR, TG, and SEM confirmed that the sequential treatment with the optimum conditions altered the structural behaviour of the original ramie fibre, which performances were similar to the mercerized ramie fibre. The barium value of sequentially iso butanol solvent treated fibre showed a greater level (213) compared to caustic mercerized fibre (179), indicating a significant advantage of mercerization performance was achieved. This advantage may be linked to improved colourfastness and handling qualities. Furthermore, the breaking force of both ramie fabrics was increased after the alkaline treatment and the sequential alkaline and iso-butanol treatment.
View
... In that sense, the dehydrated hydroxide ions decrease and diffuse easily into the crystalline structure of cellulose I, allowing the cellulose network to swell and relax until it becomes less rigid. As hydroxide ions are removed from the crystal lattice, the chains reorganize into cellulose II (Liu and Hu 2008;Jin et al. 2016). Table 3 presents the crystallinity index (CI) of CNF from the bolaina sawdust and other lignocellulosic materials. ...
... The differences in crystallinity between the two CNFs can be explained by the alkaline purification method to which the alpha-cellulose sample was subjected. According to Liu and Hu (2008), alkaline hydrolysis at high The holocellulose CNF displayed a typical cellulose I shape in the X-ray diffraction pattern, whereas the alpha-cellulose CNF exhibited cellulose II planes. The crystallinity index of alpha-cellulose CNF was higher than that of holocellulose CNF owing to a combination of factors, including the removal of hemicellulose during the sample preparation process. ...
Maximizing bolaina wood utilization: extraction of cellulose nanofibers from sawdust waste
Article
Full-text available
  • Mar 2024
  • EUR J WOOD WOOD PROD
This study focuses on the utilization of bolaina sawdust waste from the Peruvian Amazon for the production of cellulose nanofibers (CNFs). Bolaina is known for its rapid growth and extensive wood usage, which generate significant amounts of sawdust waste. The objective of this research was to physicochemically study this biomass source and the conversion of this waste into valuable nanocellulosic materials. The results showed that CNF yields from holocellulose (CNF-BH) and alpha-cellulose (CNF-Bα) gave high nanofibrillation yields of 80.6% and 74.7%, respectively. The CNFs were disintegrated into nanoscale fibers using microfluidizer treatment, resulting in CNF-BH displaying a thicker, gel-like aspect, while CNF-Bα showed a more liquid aspect. The FTIR spectra showed peaks associated with -CH2 groups, C = O stretching vibrations of carboxyl and acetyl groups in hemicelluloses, and cellulose I and II vibrations. TGA analysis demonstrated that both CNFs had two stages of degradation, with a maximum peak degradation temperature of 240 °C in the first stage and 310 to 350 °C in the second stage. The XRD patterns of CNF-BH and CNF-Bα showed differences in the crystallinity index, with values of 68.1% and 75.4%, respectively. The differences in crystallinity between the two CNFs can be explained by the alkaline purification method to which the alpha-cellulose sample was subjected. Overall, the CNFs exhibited a high crystallinity index and thermal stability, making them promising candidates for various applications in materials science and aiding in the development of sustainable materials.
View
... For BF, two apparent peaks with 2θ at 15.37°and 21.87°were observed corresponding to the (101) Fiber and (002) of natural cellulose fiber. [43] The XRD pattern of BF@TiO 2 was similar to that of BF, except for a new low-intensity diffraction peak at 2θ of 25.29°which was attributed to the (101) TiO2 plane. The diffraction peaks corresponding to (004) and (200) of the nano-TiO 2 were not detected due to the low concentration of nano-TiO 2 solution (0.035 mol/L) on the BF surface and the relatively weak intensity of these two lattice planes individually. ...
Origin and Nucleation Kinetics of Transcrystalline Layer in Bamboo fiber@nano‐TiO2/Polypropylene Composite
Article
Full-text available
  • May 2024
Herein origin and nucleation kinetics of transcrystalline layer (TCL) in bamboo fiber deposited with nano‐TiO2 (BF@TiO2)/polypropylene (PP) composite is studied. Firstly, the surface morphology, roughness, and energy, as well as crystalline structure (e. g., crystal face indices (hkl)) of BF@TiO2 are analyzed to clarify the origin of TCL in the composite. Subsequently, the nucleation kinetics of TCL in BF@TiO2/PP composite at different crystallization temperatures (Tc) are investigated through polarized optical microscopy. The results find that the surface roughness and energy of BF@TiO2 increase by 47.55 % and 2.41 % compared with untreated BF, respectively. Interestingly, the mismatch rates (MRs) of hkl(BF) vs. hkl(PP) are >320 %. In comparison, the MRs of (101)(BF@TiO2)TiO2 vs. (hkl)(PP) are dramatically decreased to <25 %, suggesting a similar crystal plane between BF@TiO2 and PP matrix. These results indicate that the TCL formation in the composite is more facile in BF@TiO2 than in the untreated BF. During isothermal crystallization, the nucleation and spherulite growth rates decrease as the Tc increases. The interface free energy difference (▵σ) between BF@TiO2 and PP is calculated based on the heterogeneous nucleation theory. The ▵σ is 1.54±0.11 J cm⁻², highlighting that the BF@TiO2 strongly induces the PP nucleation.
View
... Given their abundance in nature, natural fibers have increasingly replaced synthetic fibers as a primary raw resource. Natural fibers have a wide range of possible uses, including in textiles [8]. Numerous studies on the mechanical characteristics of natural fibers have been conducted, including those of wood (9). ...
Comparative Study of the Effects of Treatment Methods on the Tensile Performance of Bamboo
Article
Full-text available
  • May 2024
Bamboo, Effects, Tensile Performance, Treatment Methods. Bamboo is a rapidly replenishing resource that is used as a practical building material in many nations. However, it is not commonly used in the United States or other western nations, in part because building codes and safety standards have not yet included it. The mechanical characteristics of bamboo must be thoroughly comprehended and recorded in order to develop these. Major variables, including age, bamboo species, density, moisture content, post-harvest treatment, and the testing standards used, affects its properties greatly. This work presents a comparative study of the effects of treatment methods on the tensile performance of bamboo. In this research, bamboo samples of size 12x12mm, 14x12mm, 16x12mm and 20x12mm were prepared, some of the samples were treated with epoxy, bitumen emulsion, binding wire and some were treated by combining binding wire and either of epoxy or bitumen emulsion while few were untreated. Tensile strength test was carried out on both samples and the results shows that the tensile strength of bamboo samples was greatly increased in all the treatment methods used. Tensile strength of bamboo is also a function of size, from the research, it was observed that size 20mmx12mm possess higher strength. Hence, it is recommended for construction works, bamboo treated with epoxy has higher strength other treatment methods. However, a combination of binding wire and other treatment techniques give superior strength, epoxy was observed to have demonstrated higher strength than bitumen and binding wire alone.
View
... X-ray diffraction, often known as XRD, is a non-destructive and expeditious type of analytical technique that is frequently utilized for the determination of the chemical properties of natural fibers [107,124,125]. The spectrum obtained from the experiments, which correspond to a specific fiber, exhibits the diffraction peaks associated with both the amorphous and crystalline areas. ...
Recent advancement in nanocellulose synthesis, characterization and application: A review
Article
Full-text available
  • Apr 2024
Cellulose Nanocrystal, known as CNCs, is a form of material that can be produced by synthesizing carbon from naturally occurring substances, such as plants. Due to the unique properties it possesses, including a large surface area, impressive mechanical strength, and the ability to biodegrade, it draws significant attractions to the researchers nowadays. Several methods are available to prepare CNC, such as acid hydrolysis, enzymatic hydrolysis, and mechanical procedures. Characterization of CNC includes X-ray diffraction, transmission electron microscopy, and dynamic light scattering, etc. In this article, recent development of CNC preparation and their characterizations are thoroughly discussed. Significant breakthroughs are listed accordingly. Furthermore, a variety of CNC applications such as paper and packaging, biological applications, and energy storage, etc. are illustrated. This study demonstrates the insights of using of CNC as the potential environmentally friendly materials with remarkable properties.
View
... Consequently, the volume of hydrated hydroxide ions decreased and penetrated the cellulose lattice more easily, leading to a gradual expansion of the cellulose structure and subsequent dehydration and cleavage into smaller monomeric products. In addition, the size of hydrated hydroxide ions increased with increasing temperature (Liu and Hu 2008). Therefore, the removal of cellulose, hemicellulose, and lignin by NaOH decreased with increasing temperature (Table S2). ...
Enhanced adsorption of dye wastewater by low-temperature combined NaOH/urea pretreated hydrochar: Fabrication, performance, and mechanism
Article
Full-text available
  • Apr 2024
  • ENVIRON SCI POLLUT R
The highly stable biomass structure formed by cellulose, hemicellulose, and lignin results in incomplete conversion and carbonization under hydrothermal conditions. In this study, pretreated corn straw hydrochar (PCS-HC) was prepared using a low-temperature alkali/urea combination pretreatment method. The Mass loss rate of cellulose, hemicellulose, and lignin from pretreated biomass, as well as the effects of the pretreatment method on the physicochemical properties of PCS-HC and the adsorption performance of PCS-HC for alkaline dyes (rhodamine B and methylene blue), were investigated. The results showed that the low-temperature NaOH/urea pretreatment effectively disrupted the stable structure formed by cellulose, hemicellulose, and lignin. NaOH played a dominant role in solubilizing cellulose and the combination of low temperature and urea enhanced the ability of NaOH to remove cellulose, hemicellulose, and lignin. Compared to the untreated hydrochar, PCS-HC exhibited a rougher surface, a more abundant pore structure, and a larger specific surface area. The unpretreated hydrochar exhibited an adsorption capacity of 64.8% for rhodamine B and 66.32% for methylene blue. However, the removal of rhodamine B and methylene blue by PCS-BC increased to 89.12% and 90.71%, respectively, under the optimal pretreatment conditions. The PCS-HC exhibited a favorable adsorption capacity within the pH range of 6–9. However, the presence of co-existing anions such as Cl⁻, SO4²⁻, CO3²⁻, and NO3⁻ hindered the adsorption capacity of PCS-HC. Among these anions, CO3²⁻ exhibited the highest level of inhibition. Chemisorption, including complexation, electrostatic attraction, and hydrogen bonding, were the primary mechanism for dye adsorption by PCS-HC. This study provides an efficient method for utilizing agricultural waste and treating dye wastewater. Graphical Abstract
View
... The other condition is related to partial transition of the cellulose structure. Liu and Hu (2008) reported that the cellulose structure may swell and relax with higher NaOH concentrations, and hydroxide ions further penetrate inside cellulose and undergo transition of the cellulose structure, resulting in the transition of cellulose I into II. Previous studies indicated that this cellulose transition resulted in a decrease in crystallinity (Chen et al. 2016;Ouajai and Shanks 2005). ...
Drying Shrinkage and Mechanical Strength of Cementitious Composites with Alkali-Treated Makino Bamboo Fibers
Article
Full-text available
  • Mar 2024
Alkali-treated bamboo fibers (AFs) treated with different NaOH concentrations (5 and 10%) and treatment times (1, 12, and 24 h) were used as fillers to fabricate cementitious composites with AFs (CAFs) in the present study. The results demonstrated that alkali treatment caused the partial decomposition of hemicellulose and lignin and an increase in the surface roughness of bamboo fibers. Additionally, the amounts of calcium hydroxide in alkali-treated CAFs were higher than in untreated CAFs, and they increased with increasing NaOH concentration and treatment time. For drying shrinkage (DS) under 75% relative humidity (RH), the DS values of the CAFs significantly decreased after adding AFs compared to the DS values of untreated CAFs. Compared to untreated CAFs, the density of the 5% and 10% NaOH-treated CAFs with longer treatment times decreased by 2.9% and 5.1%, respectively. Furthermore, the tensile strength of all alkali-treated CAFs exhibited no significant differences when compared with that of untreated CAFs, while the modulus of rupture and compressive strength were significantly decreased by NaOH treatment. These results indicated that the AFs significantly improved the drying shrinkage of the CAFs and hydration retardation effect of cement pastes, while the density and mechanical strength of the CAFs decreased.
View
Journal of April
Article
Full-text available
  • Jan 2024
In the realm of civil engineering, bamboo reinforced concrete is being suggested as a substitute material alongside innovative approaches to find low-cost, sustainable alternatives to traditional reinforced concrete. In this study, the maximum load, the displacement, and the pattern of beam failures are examined by conducting a flexural test to investigate the flexural behavior of bamboo reinforced concrete beams. The experimental study on the flexural behavior of concrete beams reinforced with bamboo bars is presented in this paper. Based on load carrying capacity, deflection, failure pattern, and ductility, the flexural behavior is examined. The bamboo reinforced concrete beam with 1%, 2%, 3%, 4%, 5%, 6% and 7% longitudinal bamboo reinforcements specimens were prepared. The bamboo reinforced concrete beam has the maximum load, the displacement, and the beam failure pattern that are most similar to the reinforced concrete beam with that of steel reinforcement. According to a comparison of the various treatment methods, beams reinforced with bamboo possess higher flexural strength than the unreinforced concrete beams, Epoxy and binding wire treated bamboo reinforced concrete beams has higher strength than those treated with just epoxy or bitumen emulsion. This implies that the tensile strength of the bamboo as well as it bonds strength with concrete is improved with binding wire aside the chemical treatment. These research discovered that bamboo is an excellent longitudinal reinforcement alternative in reinforced concrete beams for small-scale structures. Introduction In the building industry, using non-renewable materials contributes to the excessive consumption of power and the waste of large amounts of fabric. For this reason, the building industry is in the midst of a renaissance in the use of alternative materials. With its physical and mechanical features that ensure overall performance as a building material and its cheap cost, quick growth, and perennial nature, bamboo presents an opportunity in response to the seemingly unending search for renewable materials (1). Due to its heterogeneity (1, 2), bamboo's lack of standards limits its application in the building industry. Despite the enormous variety of bamboo species, Brazil offers cheap costs, self-sufficiency, and an exceptionally smooth handling
View
View
Enhancing the Durability of Linen-Like Properties of Low Temperature Mercerized Cotton
Article
  • Feb 2004
In order to develop durable linen-like cotton yam with low temperature mercerization, pretreatment methods ensuring efficient and uniform penetration of the low temperature alkali solution into cotton yarn are studied. Pretreatments consisting of an alkaline scouring at higher NaOH concentrations and of a cellulase treatment and subsequent alkaline scouring are evaluated for their efficiency in removing wax and enhancing absorptive properties. The cellulase treatment/alkaline scouring is more efficient at re moving wax than alkaline scouring at higher NaOH concentrations. The cellulase treat ment and subsequent alkaline scouring result in wax contents lower than 0.1%. The cellulase treatment appears to degrade the cellulose on the surface of the cotton fibers, making it more accessible to the scouring agent and making wax removal easier. Swelling and wetting times are compared to identify a pretreatment sufficient for developing linen-like cotton. In low temperature mercerization, the pretreatment consisting of cellu lase treatment and alkaline scouring yields a linen-like cotton yarn whose stiffness is durable to knitting, wet processing, and even ten laundering cycles. The durability appears to be sufficient for practical applications of the process for producing linen-like cotton.
View
Mercerization of Ramie: Comparisons with Flax and Cotton: Part I: Effects on Physical, Mechanical, and Accessibility Characteristics
Article
  • Aug 1989
The effects of slack and tension mercerization on selected physical and accessibility characteristics of ramie were compared to the effects of the same treatments on flax and cotton. Slack mercerization of ramie and flax resulted in considerable losses in yam strength, while tension mercerization resulted in increased strength. Increased yarn strength was seen in both slack and tension mercerized cotton yarn. The effects of mercerization on ramie fiber cross-sectional parameters included increases in pe rimeter and area with no change in circularity. Little apparent change in fiber size or shape occurred in flax fibers, while the primary effect on cotton was increased circu larity. Increases in fiber accessibility were seen in all mercerized fibers, but the mag nitude of change in flax was approximately half of that in ramie and cotton. For all three fibers, the extent of swelling and modification in accessibility was greater under slack conditions.
View
Evaluation of improvement of physical and mechanical properties of bamboo fibers due to alkali treatment
Article
  • Jan 2008
  • J APPL POLYM SCI
Bamboo strips treated with caustic solutions of different concentrations, e.g., 5%, 10%, 15%, 20%, 25%, and 50%, were subjected to mechanical testing giving stresses on tensile strength, percent elongation at break, flexural strength, flexural modulus, and toughness. The change in average density was −15%, and the weight loss value shows a maximum of 21.94% at 50% alkali treatment. The mechanical properties of bamboo strips increase steadily with increasing concentration of caustic soda, showing a comparable increased value at 15 and 20%, and then exhibiting a gradual fall. The percent elongation at break corroborates these observations showing a continuous decreasing trend. The properties under investigation exhibit a clear transition in between 15 and 20% alkali concentration. The morphology of strips was studied by scanning electron microscope and polarizing light microscope. The crystal structure of both untreated and treated strips was compared by XRD analysis. In both cases, the breakdown of the crystal structures of the cellulose fibers and the recrystallization or reorientation of the degraded chains that are devoid of hemicellulose are quite apparent. However, at a very high concentration (to the extent of 25%) the breakdown of structure predominates much more over the reorientation or recrystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
View
Influence of Mercerization on the Dynamic Mechanical Properties of Bamboo, a Natural Lignocellulosic Composite
Article
  • Aug 2006
Bamboo fibers that have been treated in NaOH solutions of varying concentrations were subjected to differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) studies, respectively. The moisture desorption peak (and the enthalpy values associated with it) was moved to higher values as the alkali concentration increased up to 15% and shifted to lower values beyond that temperature. A broad exotherm was observed in all of the DSC curves for alkali treatments up to 15%. Beyond that concentration, two comparatively smaller exothermic peaks appeared for the 20% and 50% alkali-treated samples. DMTA study of bamboo strip samples reveals that the room-temperature value for the storage modulus (E‘) of the untreated bamboo strips is increased by 400% in the case of 15% alkali-treated samples, and the rate of decrease in the modulus over the temperature range of 140−180 °C is also maximum for those samples. The untreated bamboo samples show a primary loss modulus (E‘ ‘) peak at 111.8 °C, which is shifted to higher temperatures for alkali-treated samples. The damping parameter (tan δ) is also maximum for untreated samples.
View
Influence of alkali treatment on the fine structure and morphology of bamboo fibers
Article
  • Sep 2006
  • J APPL POLYM SCI
Bamboo fibers in the form of strips and dust were treated with NaOH solution of varying concentration (10, 15, and 20%). These treated and untreated samples were then subjected to FTIR and morphological studies. Again XRD study was carried out on those treated and untreated bamboo samples in both strip and dust form. It was found that during alkali treatment a lattice transformation from cellulose-I to cellulose-II took place. It is observed from IR index value that the conversion is maximum in between 15 and 20% of alkali treatment. Swelling in NaOH introduces considerable changes in crystallinity, orientation angle, etc. Degree of crystallinity and crystallinity index for bamboo strips increases with increasing treatment concentration of alkali and falls off after 15% alkali concentration. This is also supported by d-spacing value. Orientation factor fx was calculated from the FWHM and it was found that fx value has been increased from 0.9879 to 0.9915 for 15% alkali treated and again lowered to 0.8522 for 50% alkali treated samples. Same observation of X-ray study was obtained for dust samples but at an earlier concentration. Morphological study of bamboo dust with scanning electron microscope indicates fibrillation at higher alkali concentration. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5050–5056, 2006
View
Mercerization of cellulose. II. Alkali–cellulose intermediates and a possible mercerization mechanism
Article
  • Jan 1985
  • J APPL POLYM SCI
Continued study of the five crystalline Na–celluloses, previously shown to occur as intermediates during the mercerization of cellulose and exhibiting two types of crystallographic fiber repeats, further indicates that they fall into three classes based on their unit cells and NaOH contents. In one class are Na–celluloses I and III, both containing up to 34% NaOH; in the second class are Na–celluloses IIA and IIB, marked by ca.15 Å fiber repeat and containing up to 65% NaOH; and in the third class is Na–cellulose IV which is likely to be a hydrated form of cellulose II. Na–cellulose I was found to be the common first alkali–cellulose structure produced in the NaOH treatment of both cellulose I and cellulose II. Further study of this conversion step suggested a mercerization mechanism in which the alkali begins the conversion of cellulose to Na–cellulose I in the amorphous parts of the fiber. The conversion of the parallel-chain cellulose I structure to an antiparallel one is likely to occur already in this first step.
View
Role of mercerization of the bamboo strips on the impact properties and morphology of unidirectional bamboo strips–novolac composites
Article
  • Feb 2007
  • POLYM COMPOSITE
Bamboo strips were mercerized with varying concentrations of NaOH (10, 15, 20, and 25%). Impact test was made on composites made from the untreated as well as from the mercerized strips. Works of fracture for all the composites were evaluated and it was observed that the fracture energy undergoes an increase from composites made of untreated bamboo strips to those made from mercerized bamboo strips. Mercerization removed alkali sensitive material from the bamboo matrix and it leads to more cellulose fibril pull-out from the lignocellulosic composites, which plays a great role in improving the work of fracture value. POLYM. COMPOS., 28:57–60, 2007. © 2007 Society of Plastics Engineers
View
Effects on surface properties of natural bamboo fibers treated with atmospheric pressure argon plasma
Article
  • Aug 2006
  • SURF INTERFACE ANAL
Argon plasma at atmospheric pressure was used to improve the wettability and dyeability of natural bamboo fibers. Optical emission spectroscopy (OES) was employed to characterize the discharge. SEM and scanning probe microscopy (SPM) analyses show that the fiber surface becomes rougher after plasma treatment because of the effects of plasma bombardment and etching. The wettability and dyeability are significantly enhanced after plasma treatment. Longer treatment time, leading to rougher surface, results in better surface wettability and dyeability. These results reveal that atmospheric pressure argon plasma treatment is an effective method to improve the performance of bamboo fibers. Copyright © 2006 John Wiley & Sons, Ltd.
View
Effects of mercerization of bamboo strips on mechanical properties of unidirectional bamboo - Novolac composites
Article
  • Apr 2006
  • J APPL POLYM SCI
Bamboo strip reinforced novolac resin composites were fabricated using bamboo strips that were treated with varying concentrations of sodium hydroxide solution at a constant filler loading (25%). The mechanical properties of various composites (flexural modulus, toughness, tensile strength, and elastic modulus) were determined. The physical characteristics, such as the wetting ability of the alkali treated reinforcements, were increased because of alkali treatment. With increasing concentrations of alkali, a higher percent loss in weight occurred. The mechanical properties were increased with increasing mercerizing strength. Maximum improvement in properties was achieved with 16–20% of caustic treated reinforcements. An FTIR study indicated aryl alkyl ether formation with OH groups of cellulose and methylol groups of novolac resin. Beyond 20% there was degradation in all strength properties because of the failure in the mechanical properties of the reinforcements. A correlation was found to exist between the mechanical properties and the developed morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:238–244, 2006
View
Effect of chemical reagents on the fine structure of cellulose. Part IV. Action of caustic soda on the fine structure of cotton and ramie
Article
  • Aug 1966
  • J Polymer Sci 1 Polymer Chem
An x-ray study has been made of the changes in lateral order that take place on the treatment of cotton and ramie with different concentrations of caustic soda at 0 and 20°C. When mercerization conditions are reached it is found that there is an increase in lateral disorder in the fibrils. The x-ray diagrams from samples treated in the higher concentrations of caustic soda reveal a residual diffraction effect that can be interpreted in terms of a special type of cellulose sheet. This result implies one extreme of lateral disorder that is present in the fine structure of these materials. Indication is given how these lateral disorder phenomena can affect reactivity.
View