The above results show that the thermal conductivity of materials
increases when there are CB and CNT. At a temperature of 30oC, with 40pkl
CB, the thermal conductivity of the material increased slightly from 0.509 to
0.574 W/mK, while only 1 pkl of combined CNT replaced the thermal
conductivity CB of the material increased sharply (to 0.691 W/mK).
When raising the temperature, the thermal conductivity of rubber
blend samples increased. For blends that do not contain reinforcement fillers,
the thermal conductivity does not increase significantly. Meanwhile, blends
contained 39CB/1CNT with the highest thermal conductivity. It is the ability
to increase high thermal conductivity when increasing the temperature so
blended rubber products based on NBR/PVC with CB and CNT can reduce
endogenous heat during operation.
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hapter 3: RESULTS AND DISCUSSION
3.1.1. Modified carbon nanotubes additive
3.1.1.1. CNT denaturation by polyvinylcloride
Dispersion results in organic solvents:
Figure 3.2: Dispersion of CNT (a) and CNT-g-PVC (b) in THF
After alkylation, on the infrared spectrum (IR) of CNT-g-PVC (figure
3.3b) compare to the IR spectrum of CNT (figure 3.3a), the absorption peaks
appear at 3048cm-1, 2914cm-1 corresponding to the valence oscillation of the -
CH, -CH2 group and absorption peak at 1437cm-1 corresponding to the strain
variation of the -CH2 group in the -CH-CH2- group. In addition, an absorption
peak at 618cm-1 is found with the valence oscillation of the C-Cl bond.
Figure morphological structure of materials: The morphological
figure structure of CNT not denatured and CNT-g-PVC is studied by FE-
SEM method, results are shown in figure 3.5 below:
7
Figure 3.5: FE-SEM image of the surface of CNT (a) and CNT-g-PVC (b)
After oxidation, the structure is quite uniform with less shrinkage,
diameter of CNT-g-PVC increase significantly up to 23.6 - 29.1nm (CNT
diameter before joining PVC chain only 9.26 to 15.1nm).
3.1.1.2. Modifying CNT surface with PEG
CNT surface modification diagram by PEG is described in Figure 3.9:
Figure 3.9: Diagram of denatured CNT surface by Fischer esterification reaction
On the spectrum of CNT-(CO)-PEG (Figure 3.10), there is a peak of
3264cm-1 characteristic for oscillation of OH group at the end of circuit CNT-
COO-(CH2-CH2)n-OH, pic 3624cm-1 and 1668cm-1 denotes the signal of the
NH group, the peak 1716cm-1 is the strong signal of the group (C = O) ester.
The IR spectrum of CNT-(CO)-PEG also appears 1038cm-1 pic assigned to the
CO group in PEG, the two peaks 2836 cm-1 and 3019cm-1 characterize the
symmetric oscillation and antisymmetry of the joint C-H link in PEG.
+ Content group -(CO)-PEG and group -(CO)-TESPT paired on CNT:
Content group -(CO)-PEG and group -(CO)-TESPT grafted onto CNT
surface is also determined by the method of distribution Heat buildup (TGA).
Results analysis is obtained, shown in Table 3.4.
Table 3.4: Results of TGA analysis of CNT-(CO)-PEG and CNT-(CO)-TESPT
Sample
Starting
decomposition
temperature
Strong
decomposition
temperature
most 1, oC
Strong
decomposition
temperature
most 2, oC
Mass loss
to 750oC,
(%)
CNT 4900C 629.77 0C - 13.50%
CNT-(CO)-PEG 4050C 449.150C 619.110C 36.63%
The thermal decomposition of CNT-(CO)-PEG starts at about 4050C
and reaches a peak at 449.150C, extending until 619.110C, then the speed
decreases until it reaches 7500C no longer losing weight, at this level of mass
loss is about 36.63%, it is possible to roughly calculate the content of CO-
PEG functional group attached to the surface of CNT corresponding to
8
23.13%. From the results of thermal analysis of the weight of CNT-(CO)-
TESPT sample, this material began to decompose at about 3990C and
occurred strongly at 446.63oC lasting until 684.26oC. Starting decomposition
temperature low as well as maximum first decomposition is low of organic
groups attached to the surface of CNT as well as the poorly structured
components of CNT begin to decay. The corresponding decomposition of the
amino group and separation of sulfur atoms according to the reaction [8]:
(CNT-COO)3Si(CH2)3S4(CH2)3Si(OH)3 Ct
0
(CNT-COO)3Si(CH2)3S-H
Next is the decomposition process of CNT and its heat-stable
components. The process lasts until about 750oC, the volume does not
change anymore, at this temperature the volume loss of the whole sample is
23.31%, so that can calculate the content of the preliminary group -(CO)-
TESPT grafting on CNT surface is 9.81%.
Comment: From the research results obtained shows that:
- By alkyl reaction Fridel Craft has assembled PVC on the surface CNT with
content PVC composite is about 23.0%.
- By the surface reaction of Fischer esterification CNT (oxidized) by TESPT or
PEG, 23.13% of group (-CO)-PEG and 9.81% -(CO)-TESPT on CNT surface.
3.1.2. Denatured nano additivesilica
3.1.2.1. Determine the optimal concentration of silane
The infrared spectrum of Bis- (3-trietoxysilylpropyl) tetrasulphite
(TESPT) is shown in figure 3.2.
Figure 3.11: FT-IR of Bis-(3-trietoxysilylpropyl) tetrasulphite (TESPT)
From figure 3.11, it was found that, in the range of 4000 - 400cm-1,
TESPT has a number of characteristic absorption bands, namely: in the wave
number of 3000 - 2800cm-1, there is a fluctuation of the etoxy group, the
number of waves from 1200-1000cm-1 asymmetrical stretching oscillations
of C-O-Si, 1000 - 600cm-1 with stretching oscillation of C - C and oscillating
symmetry of C - O - Si, under 500cm-1 with knives Dynamic deformation of
C - O - Si. The oscillations of TESPT at 2990cm-1 and 1395cm-1 are
asymmetric and symmetrical strain fluctuations of the methyl group (-CH3)
in ethoxy. Pic 2883cm-1 is the asymmetric oscillation of C-H in CH3. Pic
1445 and 1395cm-1 are respectively asymmetric deformations of C - H in
methylene (CH2) and methyl groups.
9
Figure 3.12: FT-IR spectrum of
nanosilica
Figure 3.13: FT-IR spectrum of
nanosilica denatured TESPT at
different concentrations
- In the survey concentration range, the optimal concentration of silane in
order to denatured nanosilica is 2%.
- Continuing to rely on infrared spectra, comparing the intensity of peaks at
2930cm-1 and 2860cm-1, specific for C-H, the reaction time is 4 hours;
reaction temperature 300C;
- Size of silica particles after denatured:
Table 3.5: Particle size distribution of nanosilica has been denatured
% < 5 25 50 75 95
Size ( m) 0,05 0,11 0,15 0,28 0,88
Figure 3.21: Particle size distribution of nanosilica after denatured
The surface morphology of nanosilica particles before and after
denatured is described in figure 3.22.
a) Nanosilica b) Nanosilica denatured TESPT
Figure 3.22: TEM images of nanosilica particles and denatured by TESPT
10
The TEM image in Figure 3.22 can be seen, after denaturing the
nanosilica particles less agglomeration, leading to the reduction of particle
aggregation size. The results are consistent with the results of particle size
analysis in the above section.
3.1.3. Denatured nanoclay
The Nanoclay modified with HH1 (DTAB:BTAB:CTAB molar ratio of
30:5:65) is the most effective. There are basic distance characteristics d=18.6nm,
highest organic matter content (21.3%), high degree of solids in solvents.
3.2. Research and manufacture rubber nanocomposite materials
based on rubber, reinforced rubber blend with nano additives
3.2.1. Effect of nano content on the mechanical properties of materials
3.2.1.1. Effect of unmodified nano content on the tensile strength of the
material
Nano (nanosilica (NS); carbon nanotubes (CNT); nanoclay (NC) are
reinforced for the NR and rubber blend in different survey content from 1 to 10 pkl.
Figure 3.24: Tensile strength of
materials using non-denatured nano
Figure 3.25: Length of elongation of
nanomaterials not yet denatured
From the results in the table and the figures above, the content of
nano additives is suitable for each specific material background as follows:
- For NR substrate, the suitable reinforcement nanosilica content (NS) is
3pkl, resulting in maximum tensile strength and elongation when breaking.
- For rubber base blend NR/NBR nanosilica content reinforced at 7pkl,
resulting in tensile strength and elongation at maximum breaking.
- For rubber base blend NR/CR content of nanosilica with appropriate
reinforcement at 5pkl, resulting in tensile strength and elongation at
maximum breaking.
- For rubber base blend NR/NBR content of CNT reinforced at 4pkl,
resulting in tensile strength and elongation at maximum breaking.
- For rubber base blending NR/CR with appropriate reinforcement nanoclay
content at 5pkl, resulting in maximum tensile strength and elongation when
breaking
3.2.1.2. The effect of nano additive denatured on the mechanical properties of materials
Samples of materials are compared accordingly on the charts below:
11
Figure 3.26: Comparison of tensile
strength of materials using denatured
and non-denatured nano
Figure 3.27: Comparison of elongation
at breakage of materials using
denatured and non-denatured nano
From figure 3.26 and figure 3.27 charts, the drag properties of superior
denatured nano-materials compare to when not denatured
3.2.2. The influence of content nano on the figure structure of material
3.2.2.1. Figure structure of Thai NR material using nanosilica denatured and
not denatured:
The NR of 3 pkl and 7 pkl nanosilica has not been and has been
denatured by TESPT as shown in figure 3.30 and figure 3.31.
a. NR/3pkl nanosilica b. NR/3pkl nanosilica modified TESPT
Figure 3.30: Cutting surface FESEM image NR / NS 3pkl nanosilica
a. NR/7pkl nanosilica b. NR/7pkl nanosilica modified TESPT
Figure 3.31: Cutting surface FESEM image NR / 7 pkl nanosilica
From figure 3.30 and figure 3.31, it was found that, in all samples,
nanosilica particles dispersed in the NR substrate were mostly in sizes larger
than 100nm. In materials reinforced with non-denatured nanosilica (Figure
3.30a) nanosilica particles are dispersed more steadily, even with particles up
b a
a b
12
to 1 m in diameter. Meanwhile, in reinforced materials 3pkl nanosilica
denatured by TESPT, nanosilica particles are more evenly dispersed and
have particles below 100nm (Figure 3.30b). In denatured material samples of
7pkl of non-denatured and denatured nanosilica, nanosilica particles are
poorly dispersed and there appear to be quite a large set of particles in both
cases (m-Figure 3.31).
3.2.2.5. Structure of figure thai model rubber blend materials NR/CR to
strengthen organic nanoclay:
On Figure 3.35 is a snapshot of the cut surface of some material
samples from them. From the FESEM image, when the low content nanoclay
(5pkl) dispersed nanoclay particles in rubber blend are quite uniform, the
particle size is quite small only from a few hundred nanometers.
Figure 3.35: FESEM photo cut surface of rubber materials NR/CR/nanoclay
(a) 5 pkl nanoclay; (b) 10 pkl nanoclay
The figures below are X-ray diffraction diagram of nanoclay and
denatured HH1 nanoclay material HH1.
Figure 3.37: X-ray diffraction scheme of
NR/CR containing 5pkl nanoclay HH1
Figure 3.38: Sample TEM image of NR /
CR containing 5pkl nanoclay
From the X-ray diffraction scheme in Figure 3.37, the reflection peak
(d001) of nanoclay after being dispersed into rubber blend NR/CR, the
distance of nanoclay increased strongly, approximately 4.08 nm (initial base
distance d001 = 1.86nm) with 2 angle = 2,2o. This result shows that the
structure of nanoclay layers has been changed and transformed into an
interlayer structure in rubber blends. This is also evidenced by TEM image in
Figure 3.38.
a b
13
3.2.3. Effect of nano additive on thermal properties of materials
3.2.3.1. Effect of nanosilica on the thermal properties of NR material
50 100 150 200 250 300 350 400 450 500 550 600 650 700
0
20
40
60
80
100
Nhieät ñoä(
o
C)
TG/% DTG/(%/phuùt)
Toån hao khoái löôïng:93,80%
358.18
0
C, -11,15%/phuùt
-12
-10
-8
-6
-4
-2
0
100 200 300 400 500 600 700
0
20
40
60
80
100
Nhieät ñoä (
o
C)
TG/%
363.45
0
C , -11.23%/phuùt
Toån hao khoái löôïng: -92.84%
-12
-10
-8
-6
-4
-2
0
DTG(%/phuùt)
Figure 3.40.a: TGA schema of
NR/3pkl nanosilica samples
Figure 3.40b: TGA schema of NR / 3 pkl
nanosilica denatured sample by TESPT
The mechanism of linking between nanosilica denatured by TESPT
and rubber substrate can be described as follows (figure 3.42):
Figure 3.41: Illustration of the reaction between NR and nanosilica denatured TESPT
This bonding makes the material structure more rigid than the
temperature and the highest decomposition temperature is higher than the
larger compare model using non-denatured nanosilica (up to 2,850C and
5,270C respectively). This is also the reason for the mechanical properties of
materials increasecao.
3.2.3.2. Effect of nanosilica on the thermal properties of rubber blend
materials
* Thermal properties of rubber blend NR/NBR reinforced nanosilica
* Thermal properties of rubber blend NR/CR system to strengthen nanosilica
* Thermal properties of rubber blend NR/CR system for nanoclay
reinforcement:
* Thermal properties of rubber blend NR/NBR reinforced CNT.
In general, when using nano additive denatured for natural rubber and
rubber blend substrates, the thermal properties of the fabric are positively
affected. When there is a nano additive surface in the rubber base material
that shields the impact of heat for rubber elements, it has increased the
stability and thermal durability for materials.
3.3 Research, manufacturing nanocomposite rubber materials based on
rubber blend carbon black reinforcement combined with nano additive
Silica
Silica
14
3.3.1. Combine nano silica and carbon black to reinforce natural rubber
3.3.1.1. The effect of content on black carbon on the mechanical properties of materials
When the carbon black content increases: tensile strength of the
material increase fast, the abrasion resistance resistance increases such as
only a certain limit of 25pkl and then begins to decrease again. The choice of
content carbon black is 25pkl used in order to conduct further surveys.
3.3.1.2. Effect of nanosilica on the physical properties of materials
The results of examining the effect of content nanosilica on the
mechanical properties of 25pkl carbon black NR materials are presented in
Table 3.16 below:
Table 3.16: Effect of content nanosilica on the mechanical properties of NR material
containing 25pkl carbon black
Property
Content
nanosilica (pkl)
Tensile
strength
(MPa)
Elongation
tensile at break
(%)
Abrasion level
(cm3/1,61 km)
Stiffness
(Shore A)
0 21.40 643 0.985 56.0
3 22.94 663 0.948 57.1
5 23.72 655 0.944 58.3
7 19.81 632 0.973 58.8
Notice that the tensile strength, abrasion resistance, elongation and
elongation of the material peaked at optimal nanosilica content when
combined with carbon black for NR material is 5pkl.
3.3.1.3. Figure structure of the material
In order to evaluate the morphological structure of materials, we use
scanning electron microscopy (SEM) in order to capture fracture surfaces of
some typical material samples. Results are presented in figures 3.44, and
figure 3.45 below:
Figure 3.44: Surface SEM image
fracturing NR/25pkl carbon black
material sample
Figure 3.45: Surface SEM image of
fractured material NR/25pkl carbon
black/5pkl nanosilica
Realizing that, in the natural rubber model, there are 25pkl carbon
black, carbon black filler is distributed relatively evenly on the surface of the
NR platform, but there is a convex surface. When 5pkl nanosilica is added to
the sample, the sample surface retains the regular distribution of such NR
15
fillers as 25pkl carbon black reinforcement, but the surface is less convex.
This proves that with small content nanosilica still maintains the uniform
distribution of the components in the material block, the components in the
combination are better connected. Thus, the fractured surface of the material
is less convex, concave, indicating the figure structure of the tight material.
3.3.1.4. Effect of denatured process on thermal stability of materials
Table 3.17: Starting decomposition temperature and mass loss of quantitative materials
Sample
Starting
decomposition
temperature [oC]
The strongest
decomposition
temperature 1 [oC]
Weight loss
to 440 0C [%]
NR/25pkl carbon black 302.2 374.05 66,359
NR/25pkl carbon
black/5pkl nanosilica
303.6 374.07 65.829
NR/25pkl carbon
black/10pkl nanosilica
299.0 375.06 62.625
Realizing that the material's durability is a little bit higher when the
content of nanosilica denatured is 5pkl (starting decomposition temperature
increase of 1.4oC). When the nanosilica content is too high (10pkl) starting
decomposition temperature of the material falls sharply (4oC reduction). This
can be explained by the fact that the nanosilica content in the rubber
component is too large, which leads to the formation of separate phases
(such as the figure state structure indicated), reducing the tight structure of
the material leading to The thermal stability of the material decreases.
3.3.1.5. Environmental stability of materials
The aging coefficient of the material is determined according to TCVN 2229-77
after testing in the air and salt water 10% at 70oC after 96h is shown in Table 3.18.
Table 3.18: Aging coefficient of the material after testing at 70oC after 96
hours of testing in air and 10% saline
Aging factor
Samples
In the air
(%)
10% salt water
(%)
NR/25pkl carbon black 0.80 0.80
NR/25pkl carbon black/5pkl nanosilica 0.86 0.85
Realizing that, when denatured with the NR reinforcement of 25pkl
carbon black with content nanosilica is appropriate (5pkl compare to NR) has
made the increase of environment for materials (aging coefficient in air and
salt water 10% both increases significantly). This can be explained by the
presence of nanosilica which makes the material more structured, preventing
the effect of oxygen in the air as well as other aggressive elements, making
the increase environmental durability for the material.
3.3.2. Combine nano additive silica, nanoclay and carbon black to enhance
the blend of natural rubber and rubber cloropren
16
In rubber processing technology, people use many types of
reinforcing fillers such as black carbon, silica, clay, dolomite, ... However, in
each specific rubber and additive system, the fillers have influence and
content Different optimizations. In this study, the nano additive used
includes: nanosilica (NS), carbon black (CB) and nanoclay (NC) as
reinforcement for the rubber blend system NR/CR (70/30).
3.3.2.1. The effect of content on black carbon on the mechanical properties of materials
Results of the survey are presented in figures 3.47 and 3.48 below.
Figure 3.47: Effect of CB content on
breaking strength and elongation at
breaking of materials
Figure 3.48: Effect of content of CB
on hardness and abrasion of
materials
Notice that, when content carbon black (CB) increasen, tensile strength of increaseand
material reaches maximum value at content carbon black is 30pkl. Own stiffness of
increasing material gradually with the increasecontent carbon black
The change of these values is because when the CB content is within the
optimal limit of CB particles forming its network, it also separates the large rubber
molecules in all directions to form a hydrocarbon network. Two interwoven networks,
hooked together to form a rubber structure - the filler continuously enhances the
mechanical properties of the material. From the above results, the combined carbon
black content is 30pkl selected to order in order to continue research.
3.3.2.2. The effect of nanoclay content replaces nanosilica to the mechanical
properties of the material
Table 3.19: The effect of nanoclay content replaces nanosilica to the
mechanical properties of the material
Sample
(silica/clay)
Tensile strength
(MPa)
Elongation tensile
at break (%)
Stiffness
(Shore A)
Residual
extension (%)
SC0 (5/0) 22.79 608 61.4 14.0
SC1 (4/1) 23.14 632 61.8 13.8
SC2 (3/2) 24.56 653 62.0 13.2
SC5 (0/5) 22.85 607 63.2 12.0
Symbols of samples:
SC0: NR/CR/5NS-30CB; SC1: NR/CR/4NS-30CB-1NC;
SC2: NR/CR/3NS-30CB-2NC; SC5: NR/CR/30CB-5NC
17
Results on table 3.19 show that tensile strength and elongation when the
material's breakage reaches the maximum value when nanosilica content is replaced
with 2% nanoclay. Then, further increasecontent nanoclay replacement, these
properties of the material again reduced. Particularly stiffness of materials increases
and the residual extension is slow when the replacement content nanoclay increases.
This change in properties can be explained: on the one hand, nanoclay has better
reinforcement effect than compare to nanosilica. On the other hand, with content 2%
nanoclay in the material block can create nano additive resonance effects and thus,
tensile strength and elongation when breaking of the material is improved.
3.3.2.3. Effect of denatured process on thermal stability of materials
Thermal durability of materials is evaluated by thermal thermal analysis (TGA)
method. Results thermal analysis of models based on rubber blend NR/CR are shown
in figures and tables below:
Figure 3.50: TGA chart of material
sample NR/CR/5NS-30CB
Figure 3.51: TGA sample material chart
NR/CR/3NS-30CB-2NC
Realizing that the thermal stability of rubber blend material was significantly
improved when there was 30pkl of black coal through the decomposition start
temperature of the material increased sharply, from 280oC to 300oC.
When combining 2% nanosilica replacement with nanoclay, the thermal
stability of the material is also improved (the decomposition start temperature increases
by 6oC, the highest decomposition temperature increases by more than 3oC, percentage
of mass loss to 600oC of materials also decreased from 92.34% to 90.41%) Table 3.20.
Table 3.20: Analysis results of TGA sample rubber blend NR/CR with nano additives
Samples
Starting
decomposition
temperature [oC]
The strongest
decomposition
temperature 1 [oC]
The strongest
decomposition
temperature 2 [oC]
Weight
loss to
6000C [%]
NR/CR/5NS 280.0 347.3 443.1 91.92
NR/CR/5NS-30CB 300.0 347.4 447.8 92.34
NR/CR/3NS-30CB-2NC 306.0 350.7 446.5 90.41
3.3.2.5. Research Morphological structure of materials
Morphological structure of rubber blend material NR/CR/3NS-CB-2NC
nanocomposite is determined by methods such as emission field scanning
18
electron microscope (FESEM) and X-ray diffraction. Figure 3.53 below is a cut
surface FESEM image of the material sample.
Figure 3.52 Material cut surface FESEM image NR/CR/3NS-30CB-2NC nanocompozit
From FESEM images, nano-additives were dispersed in the rubber
substrate quite evenly with a relatively small particle size below 100nm.
Results of X-ray diffraction analysis of modified nanoclay samples
by mixture and sample NR/CR/3NS-30CB-2NC:
VNU-HN-SIEMENS D5005 - Mau Clay Na+ 38
File: Huynh-Toan-Giap-DHBK-Clay Na+ 38.raw - Type: 2Th/Th locked - Start: 0.400 ° - End: 10.000 ° - Step: 0.020 ° - Step time: 1.5 s - Temp.: 25.0 °C (Room) - Anode: Cu - Creation: 04/22/08 20:32:28
L
i n
(
C
p
s
)
0
1000
2000
3000
4000
5000
2-Theta - Scale
0.5 1 2 3 4 5 6 7 8 9 10
d
=
1
8
.
6
3
1
Figure 3.53: X-ray diffraction diagram of
nanoclay HH1
Figure 3.54: X-ray diffraction diagram of
NR / CR / 3NS-30CB-2NC
From the X-ray diffraction diagrams, the reflection peak (001) of
nanoclay appears at angle 2 = 5.2o with the base distance d = 1.86 nm
(Figure 3.53). With this base distance, the layers of the original nanoclay
remain in order. After being dispersed into rubber blend NR/CR, the base
distance of nanoclay increased to approximately 4.14 nm with the angle of
2 = 2.1o (Figure 3.54). This result shows that the structure the layers of
nanoclay have been changed and changed into interlayer structures in the
rubber base. Therefore, the physical and mechanical properties of the
material improved markedly.
3.3.3. Combined study of enhanced nano silica and black coal for blends
of natural rubber and nitrile butadiene rubber (NR/NBR)
3.3.3.1. Effect of black coal content on the mechanical properties of materials
The used black coal content surveyed in the range of 20pkl-35pkl
according to the result of the rubber content at 25pkl ratio is more
advantageous in terms of elongation when breaking and abrasion resistance.
19
Based on these results, the content of black coal of 25pkl is used to carry out
the next survey.
3.3.3.2. Effect of nanosilica on the physical properties of materials
The survey results of the effect of nanosilica content on the
mechanical properties of materials from NR with 25pkl of black coal are
presented in Table 3.23 below.
Table 3.23: Effect of nanosilica content on mechanical properties of NR material
containing 25pkl of black coal
Property
Content
nanosilica (pkl)
Tensile
strength
(MPa)
Elongation
tensile at
break (%)
Abrasion level
(cm3/1,61 km)
Stiffness
(Shore A)
3 23,12 670 0,925 60,2
5 24,82 668
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