Abstract: Tensile strength distributions of multi-walled carbon nanotubes (MWNTs), single-walled
carbon nanotube (SWNT) ropes and sub-bundles are studied by statistical approach based on the
experimental data sets. It shows that the distributions can be adequately described by a two-parameter
Weibull model. Considering further their nonlinear stress-strain behavior, the force-strain relation
and tensile strength of SWNT bundles are studied. The Weibull modulus of the sub-bundles in a
SWNT bundle can be estimated in terms of the maximum sustained force and the failure strain of the
bundle. A SWNT bundle was subjected to tensile testing using a nano-mechanical testing device. The
result suggests that the nonlinear behavior of SWNTs does affect the force-strain relation of SWNT
bundles, mainly at large strain.
Abstract: This paper presents a method for chemical functionalization of CNTs through the
combined process of UV/O3 treatment and silanization process. FT-IR and TEM were employed to
characterize the changes in surface functionalities and morphology. The results indicate improved
dispersion and attachment of silane molecules on the surface of CNTs. Epoxy matrix nanocomposites
containing functionalized CNTs showed much better dispersion with associated higher mechanical
properties than those without functionalization. These findings confirmed the improved interfacial
interactions due to covalent bonding between the functionalized CNTs and epoxy resin.
Abstract: This paper reports a study based on a novel concept of ‘self-healing’ coatings applied onto
the brittle fibre surface to reduce the stress concentrations and thus to improve the reinforcing
efficiency in a composite. The individual E-glass fibres as well as rovings were coated with a carbon
nanotube (CNT) reinforced epoxy composite. The tensile strengths were measured for the individual
and bundle fibres, which were treated statistically to determine the Weibull parameters and thus to
evaluate the notch sensitivity of the fibres with and without coating. The results indicate that the
tensile strength of the individual fibre increased by 10% after coating with neat epoxy. Coating
with epoxy nanocomposite containing 0.3wt% MWNT further improved the tensile strength.
However, increasing the nanotube content was not necessarily beneficial due to the formation of
nanotube agglomerates within the matrix. The tensile tests on fibre roving also showed a clear trend
of beneficial effect of nanocomposite impregnation on tensile strength. The rovings impregnated
with nanocomposite exhibited a more uniform strength distribution and higher strengths than those
impregnated with neat epoxy. Changes in prevailing failure mechanisms influenced by the epoxy
and nanocomposite coatings are identified.
Abstract: Thin films of poly(methyl methacrylate) (PMMA)，poly(vinyl acetate) (PVAc) and
carbon nanotube composites were produced by different coating methods. The best way to produce
the carbon nanotube / PMMA / PVAc composite film with conductive network is dispersing carbon
nanotubes in PMMA and PVAc by ultrasonic and by solution casting. Electrical resistance
responses of carbon nanotube / PMMA / PVAc composite sensors against various organic vapors at
low concentrations are investigated. The experimental results indicate that the composites have high
selectivity to various organic vapors at the same concentration. In addition, the electric resistance
response of the composites against organic vapors takes place in step with their vapor adsorption
procedure. Compatible blends of poly(methyl methacrylate) and poly(vinyl acetate) would be a
good candidate to produce a series of electrically conducting carbon nanotubes composite film
whose resistance is sensitive to the nature and concentration of an analyte in the vapor phase. The
results indicate that the carbon nanotube / PMMA / PAVc composite film can be used as a novel
organic vapor sensor to detect, quantify and discriminate various organic vapors.
Abstract: A simple method is described for preparing silver nanoparticles via photoreduction in
layered laponite suspensions without any additional reduction agent or heat treatment. The
properties of silver nanoparticles were studied as a function of the UV irradiation time.
Transmission electron microscopy (TEM) was employed to study the variation of particle shape,
size and size distribution. The crystal structure of silver nanoparticles was characterized powder Xray
diffractometry (XRD). The optical absorption spectra of silver nanoparticles were obtained by
ultraviolet-visible (UV-Vis) spectroscopy.
Abstract: Mono-dispersed silver nanoparticles with various morphologies were synthesized in large
quantities by reducing silver nitrate with ethylene glycol in the presence of poly(vinylpyrrolidone)
(PVP). The effects of the concentration of AgNO3, temperature, adding rates of PVP and AgNO3
injected into ethylene glycol as well as molar ratio between the repeating unit of PVP and AgNO3
were discussed. By varying the temperature and reaction time, silver nanocubes, nnoprisms and
nanospheres were obtained. It is indicated that at elevated temperatures, the ethylene glycol can
reduce Ag+ ion into Ag atoms, and thereby inducing the nucleation and growth of silver
nanostructures in the solution phase. In the polymer-mediated polyol process, PVP plays a critical
role in producing silver nanostructures with good stability and size/shape uniformity. As a result,
both the crystallinity of a seed and extent of PVP coverage on the seed were instrumental in
controlling the morphology of Ag nanoparticles.
Abstract: In order to obtain thin film dielectric layers with very low dielectric constants for use in
microelectronic devices, polyimide nanofoamed films has been prepared from the polyimide
precursors (PMDA-ODA) and poly(ethylene oxide) (PEO) in N,N-dimethylacetamide. The
synthesization process included blending polyimide as the major phase with a minor phase of the
thermally labile PEO blocks. The foamed films were characterized by a variety of experiments
including TG and SEM, and the experimental results indicated that the labile PEO would undergo
oxidative thermolysis to release small moleculars from the matrix so as to leave voids into the
polyimide matrix. The dielectric properties of the films were studied over broad frequency ranges.
The dependences of dielectric constant on the PEO content in the films and frequency were
discussed. The films with a proper amount of PEO displayed relatively low dielectric constant
compared to the pure polyimide film. Thin film foams with high thermal stability and low dielectric
constants can be prepared using the approach.
Abstract: It was shown that chitosan and hydroxy-aluminum pillared montmorillonites were
excellent materials for the removal of dyes and metal ions from effluent of dying and finishing.
Chitosan/ hydroxy-aluminum pillared montmorillonite nanocomposites are expected to play a
multiplex role in the treating process. In this study, the nanocomposite was prepared by incorporating
hydroxy-aluminum pillared montmorillonite into chitosan solution that diluted acetic acid was used
as solvent for dissolving the chitosan. The ratio of chitosan to the cationic exchange capacity of the
montmorillonite was about 1:1, 2:1, 3:1, 4:1 and 6:1, respectively. The nanocomposites were
characterized by XRD (X-ray diffraction), SEM (Scanning Electron Microscopy). The experimental
results indicated that the presence of hydroxy-aluminum cation was in favor of the chitosan
intercalation and the interlayers of MMT was intercalated with the bilayers of chitosan sheets. and
they can be used in absorption of organic and metal ions for dying and finishing effluent.
Abstract: This study describes a method of good dispersion and alignment of VGCFs, and examines
the effect of nanofiber content on the mechanical properties of nanocomposites. The dispersion of
nanofibers was carried out by solution blending, mechanical mixing, and sonication. Levels of 4% –
31% volume content of VGCFs were mixed with polypropylene (PP) powder, and then were
melt-mixed using a twin-screw extruder. For the further alignment of fibers, extruded rods were
stacked in the mold cavity for the compression molding. In the case of 31% volume content, tensile
modulus and strength improved by 100% and 40%, and the flexural modulus and strength increased
by 120% and 25%, respectively. The shear modulus showed 65% increase, but the strength dropped
sharply by 40%. In the transverse direction, the tensile, flexural, and shear strength decreased as more
fibers were added. The matrix modification by maleic anhydride (MAPP) increased the tensile and
flexural properties of VGCF/PP by 20% - 30% in the longitudinal direction, and 40% - 250% increase
in the transverse direction. The fiber surface treatment by plasma improved tensile and flexural
properties of untreated VGCF/PP (18 % vol) composites by 10% - 30% in the longitudinal direction,
but strength in the transverse direction decreased by 30% - 40%.