The document discusses a study investigating the effect of carbon nanotube (CNT) geometry on the quality of CNT dispersion in solvent media. The study found that CNT diameter has a significant effect, with larger diameter CNTs dispersing better due to less interaction energy between bundled tubes. CNT length was found to not have a significant influence. Experiments examined CNT dispersion through UV-Vis spectroscopy and investigated dispersion methods like high shear mixing and ultrasonication. The results provide insight into understanding CNT dispersion in different media.

1. Error! Unknown document property name.
Author:
Samuel
Chuah
21642303
CIV
4210:
Final
Year
Project
Fabrication
and
Characterization
of
Carbon
Nanotube
Epoxy
Nanocomposites:
Effect
of
the
Geometry
of
Carbon
Nanotubes

2. ii
|
P a g e
Executive
Summary
The
final
year
project
encompasses
two
fundamental
components
in
research.
Literature
review
and
experiments
were
conducted
to
study
the
properties,
problems
and
potential
of
carbon
nanotubes
(CNT).
A
lot
of
interest
is
generated
in
this
material
because
it
displays
exceptional
mechanical,
thermal
and
electrical
properties.
However,
agglomeration
is
the
biggest
problem
that
limits
the
mechanical
properties
of
CNT.
To
overcome
the
string
intermolecular
forces,
dispersion
during
fabrication
is
necessary
to
enhance
the
mechanical
properties.
Chemical
and
physical
dispersion
can
be
performed
to
achieve
this
goal.
The
conference
paper
was
produced
to
investigate
the
effect
of
carbon
nanotube
(CNT)
geometry
on
quality
of
CNT
dispersion
in
solvent
media.
Results
show
that
the
CNT
diameter
has
a
significant
effect
on
quality
of
its
dispersion
in
matrix.
It
demonstrates
that,
Bigger
the
CNT
diameter,
better
the
CNT
dispersion
in
media.
It
is
because,
the
bigger
diameter
leads
to
less
interaction
energy
in
CNT
bundle
and
make
it
easier
to
exfoliate
CNT
from
bundle.
In
contrast,
CNT
length
has
not
significant
influence
on
quality
of
CNT
dispersion
in
matrix.
It
is
because,
although
long
CNTs
entangle
each
other
more
than
short
CNTs,
entanglement
is
not
dominant
reason
and
with
constant
diameter
and
weight
quantity,
short
or
long
CNT
bundle
have
the
same
interaction
energy
in
bundle.
Accordingly,
with
constant
dispersion
energy
both
of
them
have
almost
equal
dispersion
quality
in
matrix.
We
hope
that
this
study
will
provide
insight
into
further
understanding
of
the
intricacies
of
dispersing
CNTs
in
media.
Acknowledgements
I
would
like
to
thank
my
supervisor,
Asghar
who
taught
me
a
lot
on
CNTs
as
well
as
my
lecturer,
Dr.
Wen
Hui
Duan
who
patiently
guided
me
throughout
the
year.
I
would
also
like
to
take
this
opportunity
to
thank
my
family
for
their
unending
support.

3. iii
|
P a g e
Table
of
Contents
Executive
Summary
......................................................................................................................................
ii
Acknowledgements
......................................................................................................................................
ii
Introduction
.................................................................................................................................................
1
Problem
Statement
.................................................................................................................................
1
Aim
...........................................................................................................................................................
2
Outline
.....................................................................................................................................................
2
Literature
review
..........................................................................................................................................
3
General
....................................................................................................................................................
3
a.
Synthesis
of
carbon
nanotube
......................................................................................................
3
b.
Properties
of
carbon
nanotube
....................................................................................................
3
c.
Mechanics
of
carbon
nanotube
...................................................................................................
4
d.
Characteristics
of
epoxy
...............................................................................................................
5
e.
Epoxy-­‐Carbon
Nanotube
Composite
Characteristics
...................................................................
5
f.
Mechanical
Properties
.................................................................................................................
5
g.
Themo
mechanical
Properties
.....................................................................................................
8
Specific
Topic:
Dispersion
........................................................................................................................
9
a.
Fabrication
methods
....................................................................................................................
9
b.
Polymers
to
disperse
CNT
..........................................................................................................
10
c.
Uv-­‐Vis
to
monitor
dispersion
of
CNT
..........................................................................................
10
Experimental
..............................................................................................................................................
11
Experiment
1:
Procedure
.......................................................................................................................
11
Experiment
1:
Results
and
discussion
....................................................................................................
12
a.
UV–vis
spectra
of
MWCNTs–BYK9076
solutions
........................................................................
12
a.
Effect
of
CNT
diameter
on
dispersion
........................................................................................
14
b.
Effect
of
CNT
length
on
CNT
dispersion
.....................................................................................
15
Experiment
2:
Procedure
.......................................................................................................................
16
Experiment
2:
Results
and
discussion
....................................................................................................
17
a.
High
speed
shear
mixing
................................................................................................................
17
b.
Ultrasonication:
..............................................................................................................................
18
c.
Amount
of
CNT
...............................................................................................................................
19

4. 1
|
P a g e
Introduction
Carbon
nanotube,
which
is
also
known
as
CNT
is
referred
to
the
small,
nano-­‐sized
cylindrical
tubes
composed
of
sheets
of
carbon
atoms
which
was
discovered
by
Iijima
in
1991
(S.
Iijima
1991).
At
present,
CNTs
are
hailed
as
the
building
blocks
of
nanotechnology
with
possible
applications
in
the
near
future.
This
bold
statement
arises
from
the
exceptional
mechanical,
thermal
and
electrical
properties
which
generate
interest
among
researchers
and
the
society
alike
(Montazeri,
Montazeri
et
al.
2011).
CNT
holds
the
promise
of
delivering
superior
composite
materials(Sun,
Warren
et
al.
2008),
electronic
appliances(Zhu,
Peng
et
al.
2004),
lightweight
products
in
the
sports
and
transportation
industries(Yuanxin,
Pervin
et
al.
2007).
In
relation
to
the
potential
application
in
the
construction
industry,
CNT
mechanical
properties
such
as
the
high
elastic
modulus,
tensile
strength,
flexural
strength
and
hardness
are
the
focus
of
attention
because
of
its
immense
potential
as
a
reinforcement
(Young
Seok
and
Jae
Ryoun
2005;
Zheng,
Zhang
et
al.
2006).
Problem
Statement
These
rolled
graphite
sheets
face
a
major
obstacle,
namely
the
tendency
to
agglomerate
and
entangle.
Factors
contributing
to
this
agglomeration
phenomenon
include
the
atomically
smooth
surfaces,
flexible
CNT
and
the
high
aspect
ratio
(Fukui,
Taninaka
et
al.
2007).
Moreover,
CNTs
have
small
diameters
that
tend
to
form
bundle
structures
due
to
their
substantial
van
der
Waals
interaction.
There
is
significant
dependence
of
the
thermal,
rheological,
and
mechanical
properties
of
the
CNT
nanocomposites
on
the
concentration
and
dispersion
state
of
CNT.
Literature
shows
CNT-­‐epoxy
nanocomposites
have
either
weaker
or
just
a
little
bit
higher
mechanical
properties
compare
to
that
of
pure
epoxy
(Wladyka-­‐Przybylak,
Wesolek
et
al.
2011;
Loos,
Yang
et
al.
2012).
CNT
poor
dispersion
and
weak
CNT-­‐matrix
interaction
are
being
generally
described
as
the
cause
for
this
lack
of
enhancement.
Therefore,
good
dispersion
is
necessary
to
realize
the
full
potential
of
the
CNT
mechanical
properties.
Different
methods
have
been
investigated
to
efficiently
disperse
the
CNT
such
as
high
speed
shear
mixing,
calendaring,
ultrasonication,
use
of
solvent
and
surfactant
(Rana,
Alagirusamy
et
al.
2009).
If
CNT
well
dispersed,
the
potential
filler-­‐matrix
interface
area
is
huge,
and
a
perfect
control
of
the
interfacial
interaction
is
crucial
for
obtaining
optimal
properties
(Vaisman,
Wagner
et
al.
2006).

5. 2
|
P a g e
Aim
The
goals
of
the
final
year
project
are
listed
as
follows:
1. Study
the
characteristics
of
CNT
to
realize
its
full
potential
2. Understand
the
role
of
carbon
nanotube
geometry
on
efficient
dispersion
3. Harnessing
the
superior
properties
of
nanocarbon
in
the
construction
industry
The
experiment
was
performed
to
investigate
the
effects
of
CNT
diameter
and
length
on
CNT
dispersion
and
understand
the
role
of
carbon
nanotube
geometry
on
efficient
dispersion.
Outline
This
report
provides
a
holistic
literature
review
concerning
the
synthesis,
fabrication
and
properties
of
carbon
nanotube
to
gain
in-­‐depth
background
knowledge
on
the
research
topic.
The
specific
topic
for
the
conference
paper
is
titled
“Carbon
nanotube
dispersion
in
solvent
media:
Effect
of
carbon
nanotube
geometry”.
The
next
section
describes
the
experiment
conducted
during
this
semester
with
corresponding
results
and
discussion.
The
findings
are
then
compiled
into
a
conference
paper.

6. 3
|
P a g e
Literature
review
The
literature
review
covers
two
aspects,
namely
a
general
knowledge
on
CNT
followed
by
a
literature
review
on
the
specific
topic
of
CNT
dispersion.
General
a. Synthesis
of
carbon
nanotube
During
the
early
90s,
carbon
nanotubes
were
first
synthesised
by
arc-­‐evaporation.
Similar
to
electrolysis,
the
process
requires
two
pure
graphite
electrodes
and
a
power
supply
but
there
is
no
electrolyte.
Instead,
the
chamber
is
filled
with
inert
gas
such
as
argon
or
helium
as
the
graphite
anode
is
vapourised
and
deposited
on
the
cathode.
The
carbon
vapour
condenses
on
the
cathode
to
form
deposits
of
nanotubes
(Jones,
et.
al.,
1996).
The
set-­‐up
is
in
Figure
1.
Figure
1
Schematic
diagram
of
the
modified
arc
evaporation
apparatus
(Coll,
et.
al.,
1992)
Nevertheless,
other
methods
can
be
employed
to
obtain
carbon
nanotubes.
Those
methods
include
laser
ablation,
gas
phase
catalytic
growth
from
carbon
monoxide
and
chemical
vapour
deposition
form
hydrocarbons
(Nikolaev
et.
al.,
1999).
b. Properties
of
carbon
nanotube
Carbon
nanotube
is
touted
as
the
construction
material
of
the
future
because
of
their
high
strength-­‐to-­‐weight
ratio.
Pipes
et.
al
investigated
the
relationship
between
chiral
integers
and
density,
while
establishing
the
density
of
carbon
nanotube
at
1.4g/cm3
for
single-­‐walled
carbon
nanotube
and
a
maximum
of
2.1
g/cm3
(2003).
As
a
comparison,
steel
has
a
density
of
7.84g/cm3
,
making
carbon
nanotube
an
interesting
proposition
especially
in
terms
of
material
mobility
at
site.

7. 4
|
P a g e
The
strength
and
stiffness
of
carbon
nanotube
are
best
described
by
their
high
tensile
strength
and
elastic
modulus
respectively.
A
background
in
quantum
chemistry
is
required
to
explain
the
unique
mechanical
property
of
carbon
nanotube.
The
chemical
bonding
within
nanotubes
consists
of
sp2
bonds,
similar
to
those
of
graphite.
These
bonds
or
rehybridisations,
which
are
stronger
than
the
sp3
bonds
found
in
alkanes
enable
nanotubes
to
possess
superior
strength
(Ebbesen,
1997).
In
addition,
carbon
nanotubes
are
good
thermal
conductors.
Kim,
et.
al.
demonstrated
that
the
room-­‐temperature
thermal
conductivity
over
200
W/m
K
for
bulk
samples
of
single-­‐walled
nanotubes
whereas
3000
W/m
K
for
individual
multiwalled
nanotubes
(2001).
Additions
of
nanotubes
to
epoxy
resin
can
double
the
thermal
conductivity
for
a
loading
of
only
1%,
showing
that
nanotube
composite
materials
may
be
useful
for
thermal
management
applications
(Hone,
2004).
c. Mechanics
of
carbon
nanotube
The
behaviour
of
carbon
nanotube
in
response
to
loading
is
the
next
focus
of
this
study.
This
section
also
demonstrates
the
two
varieties
of
atomic
structure
which
differ
in
vector
notation
as
shown
in
Figure
2.
Chirality
is
a
vector
that
describes
the
non-­‐identical
plane.
This
characteristic
dictates
the
electrical
conductivity
and
torsional
resistance
of
the
specific
shell
of
the
carbon
nanotube.
Figure
2
Illustrations
of
the
atomic
structure
of
(a)
an
arm
chair,
(b)
a
ziz-­‐zag
nanotube
and
(c)
Chiral
vector.
(Makar
&
Beaudoin,
2003)
Generally,
carbon
nanotubes
can
be
synthesised
as
single
walled
(SWNT)
or
multi
walled
nanotubes
(MWNT).
The
defects
in
SWNTs
can
be
a
point
of
weakness
while
MWNTs
contains
many
layers
that
can
compensate
defects
present
at
any
given
layer
(Harris,
2009).
Moreover,

8. 5
|
P a g e
SWNTs
are
susceptible
to
elastic
bucking
under
high
pressure
whereas
MWNTs
have
weak
van
der
Waals
forces
but
negligible
contribution
to
both
the
tensile
and
shear
stiffness
(Thostenson
et.
al.,
2001).
d. Characteristics
of
epoxy
Epoxy
is
a
thermosetting
polymer
resulting
from
the
chemical
reaction
when
the
resin
and
hardener
are
mixed
in
equal
proportions.
Unlike
thermoplastic
materials,
epoxy
is
hard,
rigid
but
brittle.
In
the
epoxy-­‐carbon
nanotube
composite
specifically,
the
epoxy
plays
a
dual
role
of
being
an
adhesive
resin
and
a
structural
matrix.
The
physical
appearance
is
always
best
described
in
terms
of
the
chemistry
and
molecular
interactions.
An
epoxide
group
is
mixed
with
bisphenol
to
produce
an
epoxy
resin.
The
amine
groups
react
with
the
epoxide
group
to
form
a
covalent
bond
reinforced
with
dense
cross-­‐links
arising
from
the
reaction
of
the
NH
group
and
epoxide
group.
Subsequently,
the
resulting
polymer
is
a
thermoset
exhibiting
high
rigidity
and
strength
(Jin,
Qipeng
et
al.
2010).
e. Epoxy-­‐Carbon
Nanotube
Composite
Characteristics
Nanocomposites
are
engineering
materials
made
up
of
carbon
nanotube
core
embedded
in
an
epoxy
resin.
Composites
are
vital
engineering
materials
because
the
composite
utilises
the
high
strength
of
the
carbon
fibre
while
the
epoxy
matrix
serves
to
protect
the
reinforcement
in
order
to
produce
a
composite
with
better
properties
better
than
its
individual
materials
(Philip
&
Bolton,
2002).
However,
the
strength
of
the
new
material
depends
on
the
direction
of
the
load
due
to
material
anisotropy.
The
application
of
epoxy
matrix
reinforced
with
carbon
nanotube
into
the
construction
industry
is
still
premature
at
this
stage
due
to
several
shortcomings.
These
challenges
include
poorly
dispersed
multiwalled
carbon
nanotube,
aligment
problems
and
weak
interfacial
bonding
in
the
epoxy
matrix
(Kathi
et.
al.,
2009).
These
problems
are
a
direct
result
of
the
chemically
inert
nature
of
the
carbon
nanotube.
Inevitably,
carbon
nanotubes
are
supplied
as
heavily
entangled
bundles
which
results
in
agglomeration
issues.
Therefore,
several
techniques
are
available
to
produce
a
successful
composite.
The
experiments
performed
involve
manipulating
the
temperature
by
pre-­‐heating
and
the
application
of
sonication
whereby
the
samples
are
prepared
during
the
fabrication
phase.
f. Mechanical
Properties
Firstly,
the
density
and
hardness
of
the
nanocomposite
can
be
measured
easily
to
obtain
a
general
idea
of
the
mechanical
properties.
According
to
Le,
et.
al.,
the
Vickers
hardness
is
8.5
at
an
optimum
CNT
content
of
1.5-­‐2%
weight
(undated).
Zheng
et.al.
measured
the
density
of
the
MWNT
which
lies
around
1.26kg/m3
.
The
bending
strength
is
recorded
within
a
range
of
30
to
70
MPa
depending
on
the
method
of
treatment.
Meanwhile,
the
flexural
modulus
is

9. 6
|
P a g e
significantly
higher
at
1500
to
2400
MPa.
Figures
1
to
3
provides
a
graphical
representation
of
the
mechanical
properties
based
on
Zheng
et.
al.’s
experiments
(2005).
Figure
3
Correlation
between
MWNT
content
with
density
Figure
4
Correlation
between
MWNT
content
with
bending
strength

10. 7
|
P a g e
Figure
5
Correlation
between
MWNT
content
with
bending
modulus
The
Young’s
modulus
is
the
main
mechanical
characteristic
of
interest
since
it
is
related
to
stiffness
as
well
as
describing
the
correlation
between
stress
and
strain
of
the
nanocomposite.
Experimental
results
suggest
the
elastic
modulus
is
1
GPa
and
capable
of
reaching
up
to
1.29
GPa
as
the
carbon
nanotibe
fibre
is
added
to
2%
by
weight
(Sun,
et.
al.,
2011).
Certainly,
carbon
nanotubes
embedded
in
an
epoxy
matrix
displays
superior
properties
provided
several
problems
are
mitiated.
Composite
structural
properties
rely
on
the
characteristics
of
the
individual
components.
Besides
the
compatibility
of
its
component
materials,
the
interfacial
adhesion
between
the
carbon
nanotube
and
the
matrix
dictates
the
mechanical
properties
of
the
composite.
Effective
load
transfer
between
the
carbon
nanotube
reinforcement
and
the
epoxy
matrix
is
crucial
in
producing
a
strong
and
superior
composite.
Otherwise,
the
composite
mechanical
properties
will
only
be
slightly
stronger
than
an
ordinary
weak
pure
epoxy.
Research
by
Lau
et.
al.
suggested
that
the
mechanical
properties
of
the
composite
is
inferior
to
pure
epoxy
when
excessive
di-­‐methylformamide
is
used
in
treating
the
carbon
nanotube
(2005).
In
addition,
the
pull
out
of
carbon
nanotube
reinforcement
phenomenon
is
associated
to
the
weak
interface
between
the
two
materials.
Another
major
problem
is
the
dispersion
of
carbon
nanotube
in
the
matrix.
The
weak
Van
der
Waals
forces
of
attraction
between
the
carbon
nanotube
graphene
layers
will
deteriorate
the
properties
and
ductility
of
the
matrix
(Bai,
2003).
The
carbon
nanotube
reinforcement
has
a
small
diameter
which
promotes
adhesion
with
the
epoxy
matrix
and
desirable
as
an
interface
for
stress
transfer.
However,
the
downside
of
this
large
total
surface
area
is
strong
attractive
forces
between
the
carbon
nanotube
fibres
are
induced
(Gojny,
et.
al.,
2005).

11. 8
|
P a g e
g. Themo
mechanical
Properties
Temperature
plays
a
significant
role
in
influencing
the
mechanical
properties
of
the
nanocomposite.
The
inclusion
of
carbon
nanotube
fibres
will
enhance
the
glass
transition,
melting
and
thermal
decomposition
temperatures
of
the
composite.
For
instance,
the
addition
of
1%
by
weight
of
carbon
nanotube
raises
the
glass
transition
temperature
from
63
to
88⁰C.
On
top
of
that,
the
thermal
conductivity
is
improved
by
70%
(Xiao-­‐Lin,
Yiu-­‐Wing
et
al.
2005).
The
storage
modulus
G’
and
tanδ
curves
of
the
CNT/epoxy
nanocomposite
are
plotted
based
on
the
results
of
the
DMA
analysis
carried
out
by
Yan,
Ming
et.al.
in
figure
4
(2008).
Tanδ
behaves
as
an
indicator
if
the
relative
importance
of
both
viscous
and
elastic
behaviours
of
materials
such
that
tanδ
<
1
tends
to
possess
elastic
behaviour
and
acts
like
a
solid
whereas
tanδ
>
1
shows
viscosity
and
liquid-­‐like
(Jeefferie,
et.al.,
undated).
In
simpler
terms,
the
glass
transition
temperatures
can
be
estimated
from
the
peaks
of
the
tanδ
curve
versus
CNT
content.
Figure
6
Storage
Modulus
and
tanδ
as
a
function
of
temperature.
The
epoxy
based
nanocomposites
are
popular
and
attractive
research
topic
but
the
dilemma
lies
in
the
dispersion
of
CNTs
and
interfacial
bond
between
CNTs
and
epoxy.
There
are
multiple
ways
to
counteract
those
problems.
The
solution
is
to
add
functionalised
group
to
the
surface
of
CNTS.
The
use
of
a
nonionic
surfactant
is
proposed
to
treat
CNT
surface
for
nanocomposite
fabrication,
which
can
act
as
a
bridge
between
CNTs
and
epoxy
matrix
without
disturbing
CNT
structure
or
introducing
defects.
Another
method
to
improve
interfacial
adhesion
is
by
mechanical
means
such
as
using
vibratory
methods
such
as
sonication.
Once
the
CNTs
are
will
dispersed,
those
epoxy
based
composites
will
fulfill
its
potential
of
exhibiting
excellent
mechanical,
electrical
and
thermal
properties.

12. 9
|
P a g e
Specific
Topic:
Dispersion
a. Fabrication
methods
Regarding
the
original
prediction,
the
carbon
nanotube
and
epoxy
composite
should
possess
excellent
mechanical
properties
and
thermal
resistance
to
apply
as
an
effective
structural
member.
The
application
of
epoxy
matrix
reinforced
with
carbon
nanotube
into
the
construction
industry
is
still
premature
at
this
stage
due
to
several
shortcomings.
These
challenges
that
are
well
documented
laments
the
unexpected
result
of
an
ineffective
composite
as
a
result
of
poorly
dispersed
multiwalled
carbon
nanotube
and
weak
interfacial
bonding
in
the
epoxy
matrix
(Amal
and
Mahmoud
2007).
Despite
the
aforementioned
shortcomings,
there
are
several
available
techniques
to
amend
the
properties
of
epoxy
resin.
The
rule
of
thumb
centres
on
a
homogenous
distribution
of
epoxy
resin
and
increase
the
interfacial
friction
with
epoxy
matrix.
The
first
method
is
the
direct
dispersion,
commonly
known
as
mechanical
method.
Since
the
composite
is
in
nano
scale,
devices
like
the
ultrasonicator
in
a
bath
or
probe
sonicator,
high
shear
mixing
in
a
solvent,
calendaring
and
ball
milling
can
be
used
as
a
combination
in
series
or
parallel.
These
tools
are
able
to
disentangle
CNTs
from
each
other
by
means
of
vibratory
energy
or
shear
force.
Although
this
technique
successfully
separate
the
fibres
from
each
other,
a
substantial
amount
of
energy
input
is
required
besides
resulting
in
damage
and
breakage
of
CNTs
into
smaller
lengths
(Sohel
and
Mangala,
2009).
Chemical
methods
create
surface
functionalities
in
CNTs
to
promote
the
intermolecular
dispersion
by
improving
the
chemical
compatibility
or
interactions
with
a
polymer
or
solvent.
Functionalities
refer
to
the
creation
of
functional
group
on
the
CNT
surface
to
encourage
interfacial
interactions
(Young
Seok
and
Jae
Ryoun
2005).
Two
pertinent
issues
to
worry
about
when
chemical
methods
are
used
is
the
aggressive
nature
of
treatment
and
unexpected
interfacial
bonding
results.
The
most
effective
chemical
method
requires
concentrated
acids
in
the
oxidation
process.
Then
again,
the
corrosiveness
of
acids
generates
structural
defects
by
deteriorating
the
intrinsic
properties
of
CNTs,
creating
defects
and
reduces
the
aspect
ratios
of
CNT
which
result
in
degraded
mechanical
properties.
Replacing
acids
with
milder
functionalisation
processes
such
as
UV/ozone
treatment
or
plasmas
followed
by
amine,
silane
or
fluorine
treatments
limits
the
active
sites
on
the
CNT
surface,
leading
to
a
low
efficiency
of
functionalisation.
Milder
treatment
also
means
the
dispersibility
of
CNTs
in
the
composite
is
marginally
altered.
Recently,
amino
functionalisation
is
devised
to
improve
the
dispersion
and
interfacial
adhesion
of
CNTs
with
polymer
resins.
Demonstrations
suggest
strong
correlations
between
amino-­‐
functionalisation,
dispersion,
wettability,
interfacial
interaction
and
re-­‐agglomeration
behaviour
of
CNTs
and
the
corresponding
mechanical
and
thermo-­‐mechanical
properties
of

13. 10
|
P a g e
nanocomposites
(Peng-­‐Cheng,
Shan-­‐Yin
et
al.
2010).
To
sum
up,
several
targets
can
be
met
by
the
synthesis
of
amino
functionalisation.
The
uniform
dispersion
of
agglomerated
CNTs
in
the
epoxy
resin
are
stabilised
and
dispersed
CNTs
under
high
temperature
applied
for
curing
can
be
achieved
to
prevent
re-­‐agglomeration.
Application
of
surfactants
and
polymer
coatings
provides
an
interesting
prospect
to
disperse
the
CNT
fibres.
Surfactant
treatment
is
widely
considered
as
the
best
choice
of
CNT
dispersion
because
the
physical
adsorption
seldom
damages
the
CNT
structure,
nor
disrupts
the
π-­‐bond
of
CNTs
and
thus,
the
electrical
properties
are
not
perturbed
(Sun,
Nicolosi
et
al.
2008).
Other
novel
method
in
progress
worth
mentioning
to
cure
the
epoxy
is
by
exposing
the
epoxy
to
gamma
radiation
and
electron
beam
in
order
to
improve
the
thermal
stability
and
yield
strength
(Nho,
Kang
et
al.
2004).
In
essence,
continuous
efforts
are
required
to
explore
various
treatment
methods
besides
improving
the
current
treatment
practices
to
make
the
CNT
and
epoxy
a
successful
composite.
b. Polymers
to
disperse
CNT
The
literature
review
was
conducted
during
the
mid-­‐semester
break.
The
findings
of
the
literature
review
were
presented
in
point
form
in
a
presentable
manner.
Refer
to
Appendix
A
for
the
information
obtained.
c. Uv-­‐Vis
to
monitor
dispersion
of
CNT
The
literature
review
was
conducted
during
the
beginning
of
semester
2.
The
findings
of
the
literature
review
were
presented
in
point
form
in
a
presentable
manner.
Refer
to
Appendix
B
for
the
information
obtained.

14. 11
|
P a g e
Experimental
Several
experiments
were
performed
throughout
the
year.
However,
out
of
the
four
experiments
performed,
only
one
is
selected
to
be
presented
in
a
conference
paper.
The
first
experiment,
Experiment
1
describes
the
effect
of
carbon
nanotube
geometry
on
dispersion.
Meanwhile,
Experiment
2
explains
the
effect
of
ultrasonication
and
amount
of
CNT
on
the
composite
mechanical
properties.
Experiment
1:
Procedure
Experiment
1
investigates
the
effect
of
CNT
geometry
on
dispersion.
In
this
study,
the
multi
walled
carbon
nanotubes
(MWCNT)
used
was
supplied
by
NTP
Company.
Properties
of
used
CNTs
are
tabulated
in
Table
1
and
SEM
images
of
CNTs
are
illustrated
in
Figure
7.
Dispersing
agent
was
BYK9076,
an
Alkylammonium
salt
of
a
high
molecular
weight
copolymer
which
was
kindly
offered
by
Nuplex
Resins
Company.
The
solvent
was
ethanol
with
99%
purity
from
Grale
Scientific.
Table
1:
CNTs
data
provided
by
manufacturer
S-1020 L-1020 L-2040 L-4060
Main rang of
diameter (nm)
10-20 10-20 20-40 40-60
Length (μm) 1-2 5-15 5-15 5-15
Purity (%) ≥ 95 ≥ 95 ≥ 95 ≥ 95
Ash (wt %) ≤ 0.2 ≤ 0.2 ≤ 0.2 ≤ 0.2
Special surface
area (m2
/g)
40-300 40-300 40-300 40-300
Amorphous
carbon (%)
< 3 < 3 < 3 < 3
Figure
7:
SEM
image
of
used
MWCNT
in
this
research
A:
S1020,
B:
L1020,
C:
L2040,
D:
L4060

15. 12
|
P a g e
All
solutions
were
prepared
by
mixing
315.8
mg
CNT
with
40
ml
ethanol
and
79
mg
surfactant
in
a
beaker.
Thereafter
the
resulting
solution
was
sonicated
about
1
hour
by
100
KJs
dispersion
energy.
All
sonication
processes
were
carried
out
with
a
horn
sonicator
(VCX 500W)
with
a
cylindrical
tip
(19
mm
end
cap
diameter).
The
output
power
was
fixed
at
around
25W.
To
prevent
rising
the
mixture
temperature
the
beaker
of
solution
was
placed
in
a
water-­‐ice
bath
during
sonication.
UV–vis
measurements
were
carried
out
on
a
DR
5000
Spectrophotometer
with
a
wavelength
range
of
190
to
1100
nm
and
Wavelength
accuracy
of
±
1
nm
in
Wavelength
Range
200–900
nm.
Samples
were
taken
after
the
sonication
process,
diluted
by
a
factor
of
35,
resulting
in
a
CNT
content
of
0.15
mg,
and
measured
in
the
UV–Vis
spectrometer.
All
absorbance
intensities
are
used
after
baseline
subtraction.
The
ethanol-­‐surfactant
solution
was
used
to
get
the
baseline
in
corresponding
measurements.
For
each
test
3
samples
were
tested
and
the
average
of
results
was
represented.
Scanning
electron
microscopy
(SEM)
morphology
was
studied
by
using
a
JEOL
7001F
field
emission
SEM
operating
at
5
kV.
To
prepare
SEM
sample
a
drop
of
CNT
dispersed
in
solution
was
deposited
on
a
silicon
substrate,
dried,
and
coated
with
1
nm
thickness
Pt.
Experiment
1:
Results
and
discussion
a. UV–vis
spectra
of
MWCNTs–BYK9076
solutions
UV-­‐vis
spectroscopy
correlates
intensity
of
absorption
of
UV-­‐visible
radiation
to
the
amount
of
substance
present
in
a
solution.
Individualized
CNTs
are
active
and
show
characteristics
bands
in
the
UV
region.
Therefore
measured
absorbance
at
specific
wavelength
can
be
related
to
their
degree
of
exfoliation(Grossiord,
Loos
et
al.
2007).
Bundled
CNTs
are
hardly
active
in
the
wavelength
region
between
200
and
900
nm
which
is
most
probably
because
of
carrier
are
tunnelling
between
the
nanotubes(Grossiord,
Loos
et
al.
2007).
Thus,
UV-­‐vis
is
an
ideal
method
to
monitor
the
dispersion
of
CNT
in
the
organic
and
inorganic
solvent.
However,
this
relationship
is
only
true
in
a
dilute
sample.
Dilution
decreases
the
concentration
of
CNT
so
that
the
light
will
not
be
completely
blocked
off
by
the
suspension.
The
spectrophotometer
has
a
light
source
emitting
light
covering
the
entire
visible
spectrum
and
the
near
ultraviolet,
covering
a
range
of
200nm
to
800nm.
Monochromatic
light
is
passed
through
the
sample.
The
incident
light
is
reduced
in
intensity
due
to
absorption,
reflection,
transmittance,
interference
and
scattering
of
light.

16. 13
|
P a g e
Figure
8:
Normalized
UV-­‐vis
adsorption
spectrum
of
L-­‐4060
CNT
in
ethanol
(43
µg
ml-­‐1
)
at
power
of
25
W.
Figure
8
illustrates
a
normalized
UV-­‐vis
spectrum
of
L-­‐4060
CNT
in
ethanol
(43
µg
ml-­‐1)
at
continuous
power
of
25
W.
As
can
be
seen,
the
evaluation
of
the
degree
of
dispersion
of
CNTs
in
ethanol
can
be
achieved
by
recording
the
UV-­‐vis
spectra
of
the
solution.
It
can
be
clearly
seen
that
the
sample
shows
a
peak
at
about
260nm,
confirming
the
presence
of
successfully
dispersed
CNTs.
At
this
point,
it
demonstrates
the
strong
absorption
by
dispersed
CNT.
Experiments
conducted
by
(Yu,
Grossiord
et
al.
2007)
also
reported
that
the
maximum
absorbance
occurs
at
the
same
wavelength
of
260nm.
Absorbance
decreases
steadily
due
to
scattering
in
the
lower
wavelength
range
after
peak
absorbance
at
about
260
nm.
In
this
case,
Rayleigh
scattering
occurs
because
the
size
of
CNTs
is
small
compared
to
the
radiation
wavelength.
It
is
worth
pointing
out
that
CNTs
can
be
effectively
dispersed
in
ethanol
solution
by
π-­‐stacking
interaction.
The
ethanol
is
selected
over
many
other
solvents
to
homogeneously
disperse
the
CNT
due
to
some
factors.
Mainly,
the
ethanol
solvent
does
not
interfere
with
the
absorption
during
the
UV-­‐vis
test.
Moreover,
dispersion
can
be
attained
without
degrading
or
destroying
the
CNTs,
unlike
acid
treatment.
It
was
reported
in
the
literature
(Grossiord,
Loos
et
al.
2007;
Yu,
Grossiord
et
al.
2007)
that,
during
the
sonication
process
the
relative
evolution
of
the
spectrum
underneath
area
is
proportional
to
the
relative
value
of
absorbance
at
a
specific
wavelength;
Therefore,
it
was
decided
to
specify
the
absorbance
maximum
about
260
nm
and
to
plot
this
value
as
a
function
of
the
total
sonication
energy
provided
to
disperse
CNT
in
solution.

17. 14
|
P a g e
a. Effect
of
CNT
diameter
on
dispersion
To
investigate
the
effect
of
CNT
diameter
on
quality
of
CNT
dispersion
in
media
three
CNTs
with
different
diameter
were
tested.
CNTs
diameter
ranges
were
10-­‐20
nm,
20-­‐40
nm
and
40-­‐60
nm.
All
CNTs
had
equal
length
range
of
5-­‐15
µm.
More
information
of
CNTs
is
tabulated
in
table
1.
CNTs
were
dispersed
in
BYK9076-­‐ethanol
solution
as
explained
in
experimental
section
and
as
prepared
solutions
were
used
for
UV-­‐vis
analysis.
Figure
9
shows
that
the
smallest
CNT
diameter
of
10
to
20
nm
has
the
lowest
absorbance
which
is
about
0.18.
However,
the
biggest
CNT
diameter
of
40
to
60
nm
has
the
highest
absorbance
of
around
0.55
which
is
3-­‐fold
of
that
of
10
to
20
nm.
This
can
be
interpreted
as
a
CNT
with
small
diameter
is
poorly
dispersed.
Smaller
diameter
of
CNT
corresponds
to
a
large
surface
area.
This
means
CNT
with
smaller
diameter
requires
more
surfactant
molecules
to
achieve
stable
dispersion
compared
to
that
of
CNT
with
larger
diameter.
The
difficulty
in
dispersing
the
CNT
with
small
diameter
arises
from
the
stronger
van
der
Waals
attraction.
In
addition,
more
energy
is
necessary
to
overcome
the
CNT
interaction
energy
of
bundled
CNT
with
smaller
diameter
compared
to
that
of
Sample
with
the
larger
diameter
in
this
experiment.
Therefore,
with
the
constant
concentration
of
surfactant
and
energy
input
for
CNT
dispersion,
CNT
with
larger
diameter
can
be
easily
dispersed
compared
to
CNT
with
smaller
diameter.
Figure
9:
Effect
of
CNT
diameter
on
CNT
dispersion
in
ethanol
solvent.
Normalized
height
of
the
UV-­‐vis
spectra
peak
located
around
260
nm
wavelengths
for
3
different
examined
CNT
diameters,
bigger
the
diameter
better
the
dispersion.
Top
left:
Evolution
of
the
colour
of
1%
wt
CNT
0.25%
wt
BYK9076
in
Ethanol
as
a
function
of
the
CNT
diameter.
A:
10-­‐20
nm,
B:
20-­‐40
nm
and
C:
40-­‐60
nm
(solutions
are
diluted
by
a
factor
of
35).
This
statement
is
in
agreement
with
visual
observation
of
dispersed
CNT
solution
in
top
left
corner
of
Figure
3.
As
can
be
seen,
the
sample
A
which
is
10-­‐20
nm
CNT
solution
has
the
lightest
colour
and
the
sample
C
with
40-­‐60
nm
CNT
has
the
darkest
colour.
It
means
that
40-­‐60
nm
CNT
solution
has
more
suspended
CNT
nanoparticle
in
solution
compared
to
that
of
10-­‐20
nm
solution.

18. 15
|
P a g e
b. Effect
of
CNT
length
on
CNT
dispersion
The
influence
of
CNT
length
on
efficient
dispersion
of
CNT
has
been
investigated
in
this
section.
To
do
this,
two
CNTs
with
different
lengths
but
the
same
diameter
were
chosen.
CNTs
were
S-­‐
1020
and
L-­‐1020
with
1-­‐2
µm
and
5-­‐15
µm
length
respectively
and
10-­‐20
nm
diameters.
More
information
of
CNTs
is
provided
in
table
1.
Figure
4
illustrates
normalized
height
of
the
UV-­‐vis
spectra
peak
located
around
260
nm
wavelength
for
2
different
examined
lengths,
and
also
evolution
of
the
colour
of
1%
wt
CNT
0.25%
wt
BYK9076
in
Ethanol
as
a
function
of
the
CNT
length.
As
can
be
seen,
both
1-­‐2
µm
and
5-­‐15
µm
length
CNTs
have
almost
the
same
absorbance
value.
It
testifies
that
CNT
length
has
not
significant
effect
on
quality
of
CNT
dispersion
in
matrix.
Figure
10:
Effect
of
CNT
length
on
CNT
dispersion
in
ethanol
solvent.
Normalized
height
of
the
UV-­‐vis
spectra
peak
located
around
260
nm
wavelength
for
2
different
examined
lengths,
Top
right:
Evolution
of
the
colour
of
1%
wt
CNT
0.25%
wt
BYK9076
in
Ethanol
as
a
function
of
the
CNT
length.
Left:
1-­‐
2
µm,
right:
5-­‐15
µm
(solutions
are
diluted
by
a
factor
of
35).
Theoretically,
a
shorter
CNT
would
be
more
easily
dispersed
than
longer
CNT.
A
longer
CNT
will
provide
a
larger
area
for
entanglement.
However,
the
dispersion
results
in
Figure
10
shows
that
the
CNT
entanglement
is
negligible
and
the
surface
energy
is
dominant
obstacle
for
efficient
dispersion.
CNT
length
has
a
negligible
influence
on
CNT
dispersion
compared
to
diameter.
It
is
because;
the
total
Surface
area
to
volume
ratio
is
independent
from
CNT
length
but
proportion
to
inverse
CNT
radius.
Therefore,
for
a
constant
CNT
content,
CNT
length
variation
has
not
significant
effect
on
its
dispersion
efficiency.
Equivalent
amounts
of
short
or
long
CNT
with
the
same
diameter
have
equal
surface
area.
In
the
other
hand,
the
equal
amounts
of
short
and
long
CNT
with
constant
diameter
have
the

19. 16
|
P a g e
same
interaction
energy
in
bundle.
Accordingly,
both
samples
need
the
same
value
of
dispersion
energy
to
break
down
the
CNT
bundle.
Therefore,
as
Figure
10
demonstrate,
with
the
same
provided
dispersion
energy
and
surfactant
short
and
long
CNT
have
almost
the
same
quality
of
dispersion
in
solvent.
However,
the
point
here
is
that
although
CNT
length
has
not
significant
effect
on
CNT
dispersion,
it
influences
the
aspect
ratio
of
CNT.
Since
CNT
aspect
ratio
plays
a
key
role
on
reinforcement
role
of
CNT
in
CNT
nanocomposites
it
is
still
essential
to
use
long
CNT
rather
than
short
CNT.
Experiment
2:
Procedure
Three
additional
experiments
were
performed
to
investigate
the
factors
influencing
the
strength
of
the
CNT-­‐epoxy
composite.
The
variables
to
be
investigated
are
the
effect
of
shear
mixing,
ultrasonication
and
amount
of
CNT
(measured
in
terms
of
percent
mass)
on
the
mechanical
properties.
These
mechanical
properties
include
Young’s
Modulus
and
tensile
strength.
Pure
epoxy
samples
(Epoxy:
Araldite
2011)
were
prepared
to
analyse
its
properties
as
a
resin.
Since
the
weakness
of
a
composite
lies
in
its
adhesive
layer,
the
importance
of
investigating
the
behavior
of
pure
epoxy
to
the
action
of
load
and
temperature
cannot
be
underestimated.
In
addition,
MWCNTs
with
large
diameter
within
the
range
of
40
to
60
nm
are
embedded
in
the
epoxy
matrix.
On
top
of
that,
the
scanning
electron
microscope
(SEM)
will
be
utilized
to
study
the
fracture
surface.
Firstly,
either
pure
epoxy
or
CNT
composite
is
placed
into
a
mould
with
the
dimensions
stipulated
in
Table
2
to
obtain
a
dog-­‐bone
shaped
sample.
This
is
in
conformance
with
the
ASTM
International
Standards
and
the
dimensions
are
stated
in
Table
2.
Twenty-­‐four
similar
samples
were
prepared
to
perform
several
tests
later.
The
samples
underwent
high
speed
shear
mixer
and
ultrasonication
at
2000rpm
and
3500rpm
in
shear
mixer
as
well
as
15
and
30
minutes
in
the
ultrasonicator
respectively.
The
sample
was
left
to
cure.
Table
3
mentions
the
type
of
CNT
fibre
used.
Table
2
Dimension
of
sample
Dimension
Length
(mm)
Thickness
3
Width
12.7
Length
100
Span
48-­‐50

20. 17
|
P a g e
Table
3:
CNTs
data
provided
by
manufacturer
S-1020 L-1020 L-2040 L-4060
Main rang of
diameter (nm)
10-20 10-20 20-40 40-60
Length (μm) 1-2 5-15 5-15 5-15
Purity (%) ≥ 95 ≥ 95 ≥ 95 ≥ 95
Ash (wt %) ≤ 0.2 ≤ 0.2 ≤ 0.2 ≤ 0.2
Special surface
area (m2
/g)
40-300 40-300 40-300 40-300
Amorphous
carbon (%)
< 3 < 3 < 3 < 3
Upon
completion
of
the
fabrication
process,
the
samples
are
ready
to
be
tested
to
failure,
also
known
as
destructive
tests.
To
investigate
the
mechanical
properties
of
the
composite,
the
tensile
is
performed
whereby
the
ASTM
D
638-­‐10
standard
will
be
used
as
a
guide.
The
Bluehill
software
will
be
utilised
to
calibrate
the
strain
experienced
by
the
sample
when
it
is
loaded
to
failure.
The
fracture
surface
is
then
observed
by
SEM
at
room
temperature
and
cold
freeze
by
liquid
nitrogen.
Experiment
2:
Results
and
discussion
a.
High
speed
shear
mixing
Fluid
undergoes
shear
when
one
area
of
fluid
travels
with
a
different
velocity
relative
to
an
adjacent
area.
In
a
high
shear
mixer
the
tip
velocity,
or
speed
of
the
fluid
at
the
outside
diameter
of
the
rotor,
will
be
higher
than
the
velocity
at
the
centre
of
the
rotor,
and
it
is
this
velocity
difference
that
creates
shear.
This
shear
can
be
used
to
load
filler
such
as
nano
particle
in
matrix.
Figures
5
to
7
show
the
comparison
between
stress-­‐strain
curves
of
pure
epoxy
with
CNT-­‐epoxy
composite
using
high
shear
mixer.
Figure
11
Tensile
stress-­‐strain
curve
of
CNT-­‐Epoxy
fabricated
by
shear
mixing
method
(left)
and
Effect
of
tensile
speed
on
tensile
curve
(right)

21. 18
|
P a g e
This
method
couldn’t
produce
efficient
CNT-­‐Epoxy
composite
due
to
the
limitation
of
mixing
speed.
The
pure
epoxy
demonstrates
a
ductile
behaviour
as
a
result
of
the
usage
of
an
overage
hardener.
The
composite
has
a
marginally
higher
Young’s
Modulus
than
pure
epoxy
which
may
be
the
direct
result
of
insufficient
mixing
speed.
Therefore,
shear
mixing
marginally
improves
the
CNT
elastic
modulus
of
CNT.
b.
Ultrasonication:
Ultrasonication
generates
alternating
low-­‐pressure
and
high-­‐pressure
waves
in
liquids,
enabling
the
formation
and
violent
collapse
of
small
vacuum
bubbles.
The
cavitation
phenomenon
causes
high
speed
impinging
liquid
jets
and
strong
hydrodynamic
shear-­‐forces.
The
induced
effects
are
used
for
the
deagglomeration
and
milling
of
micrometre
and
nanometre-­‐size
materials
in
matrix.
Figure
8
compares
the
stress-­‐strain
curves
of
pure
epoxy
with
CNT-­‐epoxy
composite
using
ultrasonication.
Figure
8:
Effect
of
sonication
energy
on
tensile
stress-­‐strain
curve
Table
4
Effect
of
sonication
energy
on
mechanical
properties
of
CNT-­‐Epoxy
composite
Dispersion
Energy
(KJ)
Tensile
Stress
Mean
(Mpa)
Ultimate
Strain
Mean
(%)
Elastic
Modulus
Mean
(Mpa)
60
37.91
13.52
1984.22
90
39.33
10.86
2031.18
120
38.17
11.26
1982.65
180
35.35
7.87
1897.09
Generally,
all
tensile
stress-­‐strain
curves
show
that
the
stress
increases
with
strain
till
a
peak
value
is
reached
before
the
stress
decreases
slightly
until
it
reaches
a
plateau
as
the
load
is

22. 19
|
P a g e
continually
applied.
Similarly,
the
relationship
also
applies
to
the
dispersion
energy
versus
elastic
modulus.
The
optimal
dispersion
energy
is
60
kJ
whereby
the
composite
elastic
modulus
is
the
maximum.
At
this
stage,
energy
is
applied
mechanically
to
physically
disperse
the
nanotubes
from
its
agglomerated
bundles.
In
other
words,
larger
dispersion
energy
corresponds
to
a
higher
rate
of
dispersion.
However,
excessive
application
of
sonication
will
result
in
damage
and
breakage
of
CNTs
into
smaller
lengths
(Rana,
Alagirusamy
et
al.
2009).
Clearly,
degradation
in
tensile
stress
and
elastic
modulus
is
observed
when
the
dispersion
energy
is
greater
than
60
kJ.
c.
Amount
of
CNT
The
tensile
test
is
performed
on
six
types
of
composite
with
varying
CNT
content
at
0,
0.1%,
0.3%,
0.5%,
1%
and
1.5%.
The
stress-­‐strain
curves
of
all
six
cases
are
summarized
in
Figure
9
while
their
corresponding
mechanical
property
values
are
stated
in
Table
4.
Figure
9:
Effect
of
CNT
percentage
on
tensile
stress-­‐strain
curve
Table
4:
Effect
of
CNT
percentage
on
mechanical
properties
of
CNT-­‐Epoxy
composite
CNT
percentage
(%)
Tensile
Stress
Mean
(Mpa)
Ultimate
Strain
Mean
(%)
Elastic
Modulus
Mean
(Mpa)
0.0
35.25
13.23
1737.66
0.1
38.17
11.26
1982.65
0.3
35.9
4.74
2001.67
0.5
35.15
6.53
1853.66
1.0
30.1
2.4
1734.21
1.5
31.18
3.46
1878

23. 20
|
P a g e
The
mechanical
properties
of
the
composite
improve
as
the
amount
of
CNT
embedded
in
the
matrix
increases.
The
optimal
percentage
of
CNT
is
0.3%
in
this
experiment
and
the
results
are
supported
by
Yuanxin
et.
al.
(2007).
The
apparent
decrease
in
mechanical
properties
is
best
described
in
terms
of
the
molecular
interactions
between
the
CNT.
The
weak
Van
der
Waals
forces
of
attraction
between
the
carbon
nanotube
graphene
layers
will
deteriorate
the
properties
and
ductility
of
the
matrix
(Bai
2003).
The
carbon
nanotube
reinforcement
has
a
small
diameter
which
promotes
adhesion
with
the
epoxy
matrix
and
desirable
as
an
interface
for
stress
transfer.
However,
the
downside
of
this
large
total
surface
area
is
strong
attractive
forces
between
the
carbon
nanotube
fibres
are
induced
(Gojny,
Wichmann
et
al.
2005).
When
the
amount
of
CNT
is
increased,
more
CNT
fibres
are
present
to
form
bundles
via
molecular
attraction.
This
reagglomeration
scenario
is
not
ideal
as
the
CNT
can
experience
a
failure
mode
called
pull-­‐out
of
fibres.
Gojny
et.
al.
also
experienced
the
same
phenomenon
and
concluded
that
the
discrepancy
is
a
result
of
the
variation
in
quality
of
dispersion
in
all
nanocomposite
samples
after
performing
sonication
(2005).
The
upper
limit
to
the
addition
of
CNT
is
4%
because
the
nanotube
content
would
be
saturated
and
this
leads
to
a
significant
increase
in
viscosity
that
causes
void
defects
in
the
composite
(Zhu,
Peng
et
al.
2004).
Conclusion
In
the
beginning
of
the
year,
a
comprehensive
literature
review
and
experiments
were
conducted
to
study
the
properties,
problems
and
potential
of
carbon
nanotubes
(CNT).
Despite
its
exceptional
mechanical,
thermal
and
electrical
properties,
agglomeration
is
the
biggest
problem
that
limits
the
mechanical
properties
of
CNT.
To
overcome
the
string
intermolecular
forces,
dispersion
during
fabrication
is
necessary
to
enhance
the
mechanical
properties.
Experiments
using
chemical
and
physical
dispersion
were
performed
to
achieve
this
goal.
Several
experiments
were
conducted
to
investigate
the
possible
factors
that
may
improve
dispersion
in
CNT
and
ultimately
improve
its
mechanical
properties.
The
second
semester
is
focused
on
the
effect
of
CNT
geometry
on
efficiency
of
CNT
dispersion
in
media.
Results
show
that
CNT
diameter
has
significant
influence
on
quality
of
CNT
dispersion
in
media,
the
bigger
diameter
the
better
CNT
exfoliation
in
matrix.
In
contrast,
CNT
length
has
insignificant
influence
on
quality
of
CNT
dispersion
in
matrix.
In
mathematical
terms,
the
total
Surface
area
to
volume
ratio
is
independent
from
CNT
length
but
proportional
to
inverse
CNT
radius.
Therefore,
for
a
constant
CNT
content,
CNT
length
variation
converse
to
radius
variation
has
no
significant
effect
on
its
dispersion
efficiency.

24. 21
|
P a g e
References
1. Amal,
M.
K.,
Esawi
and
M.
Mahmoud,
Farag
(2007).
"Carbon
Nanotube
Reinforced
Composites:
Potential
and
Current
Challenges."
Composites
Elsevier(28):
8.
2. Bai,
J.
(2003).
"Evidence
of
the
reinforcement
role
of
chemical
vapour
deposition
multi-­‐walled
carbon
nanotubes
in
a
polymer
matrix."
Carbon
41(6):
1325-­‐1328.
3. Fukui,
N.,
A.
Taninaka,
et
al.
(2007).
"Placing
and
Imaging
Individual
Carbon
Nanotubes
on
Cu
(111)
Clean
Surface
Using
In
Situ
Pulsed-­‐Jet
Deposition-­‐STM
Technique."
Journal
of
Nanoscience
and
Nanotechnology
7(12):
4267-­‐4271.
4. Gojny,
F.
H.,
M.
H.
G.
Wichmann,
et
al.
(2005).
"Influence
of
different
carbon
nanotubes
on
the
mechanical
properties
of
epoxy
matrix
composites
-­‐
A
comparative
study."
Composites
Science
and
Technology
65(15-­‐16
SPEC.
ISS.):
2300-­‐2313.
5. Grossiord,
N.,
J.
Loos,
et
al.
(2007).
"Conductive
carbon-­‐nanotube/polymer
composites:
Spectroscopic
monitoring
of
the
exfoliation
process
in
water."
Composites
Science
and
Technology
67(5):
778-­‐782.
6. Jin,
Z.,
G.
Qipeng,
et
al.
(2010).
"Thermal
and
Mechanical
Properties
of
a
Dendritic
Hydroxyl-­‐
Functional
Hyperbranched
Polymer
and
Tetrafunctional
Epoxy
Resin
Blends."
Journal
of
Polymer
Science,
Part
B:
Polymer
Physics
48(4):
417-­‐424.
7. Jones,
J.
M.,
Malcolm,
R.
P.,
Thoma,
K.
M.
and
Bottrell,
S.
H.,
(1996),
Anode
deposit
formed
during
the
carbon-­‐arc
evaporation
of
graphite
for
the
synthesis
of
fullerenes
and
carbon
nanotubes,
Vol.
34,
Pergamon
Press
Inc,
Tarrytown,
NY,
United
States
8. Coll,
B.F.,
Sathrum,
P.,
Aharonov,
R.
and
Tamor,
M.A.,
(1992)
Diamond-­‐like
carbon
films
synthesized
by
cathodic
arc
evaporation,
Thin
Solid
Films,
v
209,
n
2,
pp.
165-­‐173
9. Nikolaev
P.,Bronikowski,
M.J.,Bradley
R.K.,
Fohmund
F.,Colbert
D.T.,Smith
K.A.
and
Smalley,
R.E.,
(1999)
Gas-­‐phase
catalytic
growth
of
single-­‐walled
carbon
nanotubes
from
carbon
monoxide,
Chemical
Physics
Letters,313(1-­‐2):91–7
10. Ebbesen,
T.W.,
(1997),
Carbon
nanotubes
:
preparation
and
properties,
Boca
Raton
:
CRC
Press,
pp.
225-­‐246
11. Kim,
P.,
Shi,
L.,
Majumdar,
A.
and
McEuen,
P.L.,
(2001),
Thermal
transport
measurements
of
individual
multiwalled
nanotubes.
Phys.
Rev.
Lett.,
8721
12. Hone,
J.,
(2004)
Carbon
nanotube:
thermal
properties,
Dekker
Encyclopedia
of
Nanoscience
and
Nanotechnology
p
603
13. Pipes
R.B.,
Frankland
S.J.,
Hubert
P.
and
Saether
E.,(2003),
Self-­‐consistent
properties
of
the
SWCN
and
hexagonal
arrays
as
composite
reinforcements.
Compos
Sci
Technol,
63(10):1349–58
14. Makar,
J.M.
and
Beaudoin,
J.J.,
(2003),
Carbon
nanotubes
and
their
application
in
the
construction
industr
y,
NRC-­‐CNC
15. Harris,
P.J.,
2009,
Carbon
nanotube
science:
synthesis,
properties
and
applications,
Cambridge,
pp.
108-­‐141
16. Thostenson
E.
T.,
Ren
Z.F.
and
Chou,
T.W.,
(2001),
Advances
in
the
science
and
technology
of
Carbon
nanotubes
and
their
composites:
a
review,
Composite
science
and
technology,
pp.
1899-­‐1912

25. 22
|
P a g e
17. Loos,
M.
R.,
J.
Yang,
et
al.
(2012).
"Effect
of
block-­‐copolymer
dispersants
on
properties
of
carbon
nanotube/epoxy
systems."
Composites
Science
and
Technology
72(4):
482-­‐488.
18. Montazeri,
A.,
N.
Montazeri,
et
al.
(2011).
"Thermo-­‐mechanical
properties
of
multi-­‐walled
carbon
nanotube
(mwcnt)/epoxy
composites."
International
Journal
of
Polymer
Analysis
and
Characterization
16(3):
199-­‐210.
19. Nho,
Y.
C.,
P.
H.
Kang,
et
al.
(2004).
The
characteristics
of
epoxy
resin
cured
by
-­‐ray
and
E-­‐beam,
Elsevier
Ltd.
20. Peng-­‐Cheng,
M.,
M.
Shan-­‐Yin,
et
al.
(2010).
"Dispersion,
Interfacial
Interaction
and
Re-­‐
agglomeration
of
Functionalized
Carbon
Nanotubes
in
Epoxy
Composites."
Composites
Elsevier(48):
11.
21. Rana,
S.,
R.
Alagirusamy,
et
al.
(2009).
"A
review
on
carbon
epoxy
nanocomposites."
Journal
of
Reinforced
Plastics
and
Composites
28(4):
461-­‐487.
22. S.
Iijima
(1991).
"Helical
microtubules
of
graphitic
carbon."
Nature
354(6348):
56-­‐58.
23. Sun,
L.,
G.
Warren,
et
al.
(2008).
"Mechanical
properties
of
surface-­‐functionalized
SWCNT/epoxy
composites."
Carbon
46(2):
320-­‐328.
24. Sun,
Z.,
V.
Nicolosi,
et
al.
(2008).
"Quantitative
evaluation
of
surfactant-­‐stabilized
single-­‐walled
carbon
nanotubes:
Dispersion
quality
and
its
correlation
with
zeta
potential."
Journal
of
Physical
Chemistry
C
112(29):
10692-­‐10699.
25. Sohel,
R.,
A.
R.,
and
J.
Mangala,
(2009).
A
Review
on
Carbon
Epoxy
Nanocomposites.
Journal
of
Reinforced
Plastics
and
Composites.
26. Bai,
(2003),
Evidence
of
the
reinforcement
role
of
chemical
vapour
deposition
multi-­‐
walled
carbon
nanotubes
in
a
polymer
matrix
27. K.T.
Lau,
(2005)
Composites
Science
and
Technology
65
719–725
28. F.H.
Gojny
et
al.
(2005),
Composites
Science
and
Technology
65
2300–2313
29. Mechanical
and
Tribological
Properties
of
Epoxy-­‐CNT
Nanocomposite
Coatings
30. H.
R.
Le,
A.
Howson
and
M.
Ramanauskas
Mechanical
and
Tribological
Properties
of
Epoxy-­‐CNT
Nanocomposite
Coatings
31. John
Kathi,
Kyong-­‐Yop
Rhee,
Joong
Hee
Lee,
2009,
Effect
of
chemical
functionalization
of
multi-­‐walled
carbon
nanotubes
with
3-­‐aminopropyltriethoxysilane
on
mechanical
and
morphological
properties
of
epoxy
nanocomposites
32. Lan-­‐Hui
Sun,
Zoub
eida
Ounaies,
Xin-­‐Lin
Gao,
Casey
A.
Whalen,
and
Zhen-­‐Guo
Yang
(2011)
Prepar
at
ion,
Char
acter
i
zat
i
on,
a
nd
Mo
deling
of
C
ar
b
on
Nanofib
er/Ep
oxy
Nanocomp
osite
s
33. Philip,
M.
and
Bolton,
W,
2002,
“Technology
of
engineering
materials”,
Butterworth-­‐
Heinemann,
Great
Britain,
p.
296
34. A.R.,
Jeefferie,
M.Y.
Yuhazri,
O.
NooririnahM.M.
Haidir,
Haeryip
Sihombing,
M.A.,
Mohd
Salleh,
N.A.,
Ibrahim,
THERMOMECHANICAL
AND
MORPHOLOGICAL
INTERRELATIONSHIP
OF
POLYPROPYLENE-­‐MUTIWALLED
CARBON
NANOTUBES
(PP/MWCNTs)
NANOCOMPOSITES,
International
Journal
of
Basic
&
Applie
d
Sciences
IJBAS-­‐IJENS
Vol:
10
No:04
35. Vaisman,
L.,
H.
D.
Wagner,
et
al.
(2006).
"The
role
of
surfactants
in
dispersion
of
carbon
nanotubes."
Advances
in
Colloid
and
Interface
Science
128-­‐130:
37-­‐46.

26. 23
|
P a g e
36. Wladyka-­‐Przybylak,
M.,
D.
Wesolek,
et
al.
(2011).
"Functionalization
effect
on
physico-­‐
mechanical
properties
of
multi-­‐walled
carbon
nanotubes/epoxy
composites."
Polymers
for
Advanced
Technologies
22(1):
48-­‐59.
37. Xiao-­‐Lin,
X.,
M.
Yiu-­‐Wing,
et
al.
(2005).
"Dispersion
and
alignment
of
carbon
nanotubes
in
polymer
matrix:
A
review."
Materials
Science
and
Engineering
49:
24.
38. Young
Seok,
S.
and
Y.
Jae
Ryoun
(2005).
"Influence
of
dispersion
states
of
carbon
nanotubes
on
physical
properties
of
epoxy
nanocomposites."
Carbon
43(7):
1378-­‐1385.
39. Yu,
J.,
N.
Grossiord,
et
al.
(2007).
"Controlling
the
dispersion
of
multi-­‐wall
carbon
nanotubes
in
aqueous
surfactant
solution."
Carbon
45(3):
618-­‐623.
40. Yuanxin,
Z.,
F.
Pervin,
et
al.
(2007).
"Experimental
study
on
the
thermal
and
mechanical
properties
of
multi-­‐walled
carbon
nanotube-­‐reinforced
epoxy."
Materials
Science
&amp;
Engineering
A
(Structural
Materials:
Properties,
Microstructure
and
Processing)
452-­‐453:
657-­‐
664.
41. Zheng,
Y.,
A.
Zhang,
et
al.
(2006).
"Functionalized
effect
on
carbon
nanotube/epoxy
nano-­‐
composites."
Materials
Science
&amp;
Engineering
A
(Structural
Materials:
Properties,
Microstructure
and
Processing)
435-­‐436:
145-­‐149.
42. Zhu,
J.,
H.
Peng,
et
al.
(2004).
"Reinforcing
epoxy
polymer
composites
through
covalent
integration
of
functionalized
nanotubes."
Advanced
Functional
Materials
14(7):
643-­‐648.
43. Zhu,
J.,
H.
Peng,
et
al.
(2004).
"Reinforcing
epoxy
polymer
composites
through
covalent
integration
of
functionalized
nanotubes."
Advanced
Functional
Materials
14(7):
643-­‐648.

27. 24
|
P a g e
Appendix
A:
Conference
Paper

28. 25
|
P a g e
Appendix
B:
Project
Management
Statement
The
project
was
conducted
in
a
continuous
manner
beginning
from
the
first
week
of
the
first
semester
until
the
end
of
September
whereby
the
conference
paper
was
completed.
This
was
managed
effectively
by
prioritisation
of
tasks
with
the
guidance
of
the
lecturer,
Dr.
Wen
Hui
Duan.
The
literature
review
was
performed
individually
with
the
supervisor
providing
a
set
of
compulsory
reading
materials
to
be
reported
on
a
weekly
basis.
Software
such
as
JabRef,
Lyx
and
CTex
were
used
to
present
the
findings
in
a
systematic
and
organised
form.
On
the
other
hand,
I
assisted
the
supervisor
to
perform
the
laboratory
experiments.
In
the
first
semester,
the
first
two
weeks
were
utilised
to
familiarise
myself
with
the
topic
at
hand.
The
next
3
weeks
(Week
3
to
week
6)
were
spent
at
the
laboratory
performing
experiments.
During
that
time
period,
a
total
of
about
10
hours
were
spent
at
the
laboratory.
Tensile
tests
and
fabrication
of
CNT
epoxy
specimens
were
carried
out.
A
poster
presentation
was
delivered
Week
4
to
understand
the
requirements
of
the
task
and
begin
scoping
the
project.
In
addition,
the
literature
review
regarding
the
general
topic
of
the
“Properties,
Problems
and
Potential
of
CNT”
took
place
in
a
continuous
manner
till
the
end
of
the
semester.
At
the
end
of
the
semester
in
week
12,
a
preliminary
report
was
submitted
to
monitor
the
progress.
The
holidays
were
well-­‐spent
as
I
channelled
my
time
and
energy
on
the
final
year
project.
During
the
mid-­‐semester
break,
duration
of
four
weeks
was
set
aside
to
identify
the
specific
topic
for
the
final
year
project
and
conference
paper
submission.
As
a
result,
the
topic
of
“Fabrication
and
Characterisation
of
CNT
Epoxy
Nanocomposites:
Effect
of
the
Geometry
of
Carbon
Nanotubes”
was
selected.
As
shown
in
Appendix
A
and
B,
the
mid-­‐term
break
was
used
to
present
the
findings
in
a
presentable
manner.
During
the
second
semester,
the
first
three
weeks
was
used
to
perform
experiments
at
the
laboratory
to
investigate
the
effect
of
geometry
on
CNT.
About
12
hours
were
spent
at
the
laboratory
to
obtain
the
results.
The
remaining
time
until
the
end
of
September
was
dedicated
to
write
a
conference
paper
as
shown
in
Appendix
C.
Based
on
the
compiled
notes
gathered
throughout
the
semester,
the
literature
review
findings
were
applied
as
background
knowledge
and
references
to
help
write
the
conference
paper.
Overall,
the
unit
certainly
helped
me
to
juggle
and
manage
my
time
for
research
and
coursework.
In
addition,
the
time
used
during
the
mid-­‐term
and
mid
semester
breaks
allowed
ne
to
use
my
time
in
a
much
more
effective
manner.
As
a
result,
the
conference
paper
managed
to
be
produced
ahead
of
schedule.
Moreover,
a
full
day
(11
hours)
per
week
was
set
aside
to
familiarise
myself
with
the
topic
by
reading
the
conference
papers
in
the
database.