World Journal Of Engineering
Increased thermal stability of multi-walled carbon nanotube structure by attaching CTAB capped
zinc oxide nanoparticles
Manish Kumara, Mandeep Singhb, Dushyant Kushavaha, M.L Singlaa
a
Material Research Division, Central Scientific Instruments Organization (CSIO), Chandigarh (India)
b
Department of Chemical Engineering, Institute of Chemical Technology, Prague (Czech Republic). Email:mandeep.singh@vscht.cz
Introduction
Results and Discussion
In the XRD patterns were recorded by means of a
Rigaku D max III C diffractometer in fig 1(a) shows all
the major peaks of the ZnO nanoparticles at 31.7°,
34.34°, 36.18°, 47.47°, 56.53°, 62.79° and 67.89°
were assigned to (100), (002), (101), (102), (110),
(103) and (112) planes of hexagonal wurtzite
structured of ZnO (JCPDS Card File No. 36-1451)
accept one peak at 26.56° corresponding to MWCNT
at (002) plane indicating that the composite is a
contribution of CNT and ZnO nanoparticles and fig
1(b inset) is the TEM image (using JEOL – 1200EX)
of the composite clearly shows the attachment of
CTAB capped ZnO nanoparticle onto MWCNT
scaffolds. Thus, TEM and XRD structural study
reveals the formation of the composite powder.
The properties of multi-wall carbon nanotubes
(MWCNT’s) such as high mechanical strength or high
thermal and electrical conductivity can be further
enhanced by the addition of both organic and
inorganic substances to form composite structures. In
particular, CNT’s loaded with various types of
nanoparticles like Au [1], Ag [2], metal oxides TiO2 [3],
and ZnO [4] by using approaches including
electrostatic coordination [5], thermal decomposition
[1], seed-mediated growth [6] etc. In the present work,
we report a new and relatively facile approach to
prepare MWCNT’s composites using CTAB coated
ZnO nanoparticles. Here, CTAB (cationic surfactant)
capped ZnO nanoparticles attached the nanotube
surface due to hydrophobic and electrostatic
interactions. Further, a detailed microscopic and
thermal study of the prepared composite material is
presented and the key structural and functional
aspects of the composite are discussed.
Material and Methods
Zinc acetate dihydrate, Sodium hydroxide (NaOH),
Cetyl trimethylammonium bromide (CTAB), Nitric acid
(HNO3), Hydrochloric acid (HCl), and Isopropanol
were used as received. MWCNT’s were purchased
from Nanostrurtured & Amporphous materials Inc.
(US). For the synthesis of composite, as-received
MWNTs were first treated by refluxing in HNO3 (40%)
at 110 °C for 2 hours to improve their dispersibility in
aqueous solution by forming oxygen containing
functional groups on their side walls. Acid treated
MWNTs (10 mg) were added into 40 mL distilled H2O
and ultrasonicated for 15 min. HCl (38%, 0.7 ml) was
added during the ultrasonication (solution A). CTAB
coated ZnO nanoparticles have been synthesized
according to our previously reported method [7].
Nanoparticles were then added to acid-treated
MWNT’s from solution A under vigorous stirring and
the stirring continued for 2 h. The mixture was then
transferred to a 40 mL Teflon-lined stainless steel
autoclave and heated at 150 °C for 20 hours. The
final product was washed repeatedly with distilled
water and absolute alcohol and dried at 60 °C in
vacuum.
Fig.1 (a-b) XRD pattern and TEM image of the composite
The TGA-DSC measurements were carried out on dry
powder samples heated at a ramping rate of 5 °C/min
in the presence of an inert atmosphere using SDT-Q600 TA instrument to study their thermal structural
stability. Figure 2(a) shows the TGA-DSC curve of the
as received MWCNT’s, where 65% reduction in
weight from 450 °C to 700 °C (DSC maximum 600°C),
most likely due to the decomposition of the CNT’s.
Figure 2(b) of CTAB coated ZnO nanoparticles shows
first decrease of 2.5 % below 150 °C due to the
release of residual solvent and adsorbed water, the
second decrease of 5.7 % till 500 °C is due to
desorption and decomposition of the surfactant and
further decrease is due to the de-hydroxylation of the
surface and the removal of the residual surfactant
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World Journal Of Engineering
Conclusions
(DSC maximum 460°C). Figure 2(c) of their
composite the initial weight loss of 5.5 % up to 400 °C
is due to the release of the residual solvents and
adsorbed water, the desorption and decomposition of
the surfactant and also the decomposition of the –
COOH group of the acid treated MWCNT’s. Further
decrease of 19.8 % up to 700 °C attributed to the dehydroxylation of the ZnO nanoparticle surface plus the
removal of the any residual surfactant and also the
decomposition of the nanotubes (DSC maximum
580°C). The thermal stability of the MWCNT is
remarkably improved upto 40% by nanoparticles
incorporation.
CTAB capped ZnO nanoparticles with MWCNT
composite powder was synthesized in facile manner.
XRD and TEM analysis reveals the formation of the
composite powder. The thermal stability of the
MWCNT structure increased by 40% after the
incorporation of CTAB capped ZnO nanoparticles. As
the basic thermal properties of ZnO nanoparticles
remain preserved in the composite, the present
composite is a suitable candidate for low- to medium
temperature applications while retaining the thermal
properties of the individual components – in particular
the carbon nanotube network in the composite
material and for biomedical application-oriented
studies as Protein resistant CNT–polymer composites
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Fig.2 (a-c) TGA-DSC of (a) MWCNT, (b) CTAB/ZnO nanoparticles
and (c) their composite
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