And today I will be presenting one of my
research projects is actually conductive
composites to radical models
versus experimental data and
their reality percolation thrust so
relationship.
This is my outline for
today's presentation.
I would start off by giving an
introduction pointing out the motivation
and the challenges but should lead to
my research objectives followed by my
experimental approach including the
materials I used hollow fabricated nice
sample as the character resolutions of
the properties present my results and
data and discuss my findings in
this project with conclusions
recently did has been
increasing demand for
electrically conductive polymer
composites there have advantages
over metallic parts in terms of
a reduction in cost reduction
resistance against correlation and
some of the applications include
bipolar placing fuel cell flexible added
Tronics and added for static painting.
We wanted to public a such
composite we need to be able to
predict the electrical conductivity and
determine the percolation threshold.
The percolation a threshold is
the amount of rain forest and
require it within the matrix.
For the composite to be conducted and
there are existing theoretical models for
predicting electrical conductivity.
However.
They will propose for
Michael's sized reinforcements and
there is need to validate this models.
For an nano size reinforcements
that we used our base.
Also they do not predict
the percolation threshold and
you did that you just use of assumed
value in the model you creation or.
Another.
Approaches to deter me experimentally
by fabricating all the composites
at different loading level US
which is time consuming and costly for
them or Demi factors that I thank you.
Electrical conductivity.
But these models do not necessarily
take into account out of then.
And lastly there may be tread on
between properties adding excessive
amount of rain forest man made decrease
the mechanical performance of the material
and this leads to my research objectives.
There are two questions to be answered.
First and the theoretical models proposed
for electrically contact with composites
actually predict the electrical
conductivity of composites.
So I can tell the percolation Thraso
be determined without fabricating
the composite O. that loading levels.
Put a material as I use emacs rim and.
I use poly properly as my pally matrix.
I use carbon black and
they were grown carbon nano fibers
as my rain forest lands and
then the information in the paper in this
is other trainings for these materials.
I thought because my composite
is a mill mixing my own lemur.
With the rain forest mens
followed by injection
molding with the conditions listed here.
There I measured the electrical
conductivity of my composites and
post using the four probe method I
characterize the mechanical properties
using the three point bending
test method I characterize
the real logical properties
using a power of meter.
You wanted to compare my experimental
data with the theoretical predictions.
I used to modify.
And we are model which is
one of the most Adventists
the radical mottos in literature.
You also take seem to account the most
number of factors involving electrical
conductivity and carries the equation for
the motif I mean when your model
where a signal is the electrical
conductivity of the composite signal I see
you actually go conductivity by
the percolation threshold sigma
is the conductivity of the max fourteen
percent of used in the experiment for
the reinforcement and
five to fourteen percent of the force and
I sees the percolation
threshold at the maximum
fourteen percent of brain force me used
a small case defying the second creation.
Where capital K. and a constant space
on the chemical properties of the real.
And here is the product of of log
trickle conductivity as a function
of reinforcement volume percent.
This is a to be Co S.
curve where a low volume percent.
Their conductivity sarong
the conductivity of a pure polymer I.C.
reaches the percolation STRASSEL
conductive now well within
the poly matrix forms and
conductivity increases significantly.
But I know high volume percent.
I think extra volume
percent of re-inforcement
would increase the conductivity
significantly as the.
Now work this already.
Forms.
So for the carbon tax system
the percolation THROSSELL may be
between one point five and two percent.
And for the vapor grown carbon nano fiber
system as shape is not as obvious or
we can still see that the percolation.
Russell is somewhere between three and
five percent.
However three and
five percent say the gap and
the percolation stress so can be
anywhere between three and five percent.
So there may be some more composes
floating levels between three and
five percent that need to be fabricated
to determine the percolation stress or
more accurately.
For the mechanical properties
the fracture modulus and
factual strength with the terming
as a function of volume percent and
asked of forty percent of carbon black
goes up the modulus generally increases
the strength increases in the beginning
by reaches a plateau high volume percent
and the same trend goes for
the paper grown carbon fiber system
where the modulus just increases and
the strength also reaches a plateau.
For the real logical properties.
Discussed T. and ten Delta.
While the viscosity increases as
the volume present goes up ten dollars
actually approaches zero and ten
approaches zero between one percent and
one point five percent
of carbon black here for
the program carbon nano fiber system.
Viscosity also increases generally attend
approaches zero are around six
percent of the rain forest and.
So to compare my experimental data
with the theoretical predictions for
electrical conductivity I prodded
the men we are model equation
and using using the capital K. and
values suggested by the author
of the model and as you can see.
Well the final Miyamoto predictions match
very well with the experimental data for
the carbon black system.
However this is not the case for the vapor
grown carbon nano fiber system and
this is maybe due to the fact that
the equation requires a value for
percolation threshold Harvard
the percolation so
was I was unable to deter me I
actually asked if it could be anywhere
between three and five percent so I just
used it I just used four percent as the
average between three and five percent.
And this could be because in the deviation
and afterward to determine the percolation
Thraso without fabricating all
the samples at different loading levels.
I tried to relate all the properties to
the percolation thrice so from my results.
I noticed some correlation between
the ten Delta and percolation stress so
as you can see for the carbon black
system the percolation THROSSELL was
between one point five and
two percent and ten dollars.
Also became zero between one
point five and two percent
for the beta growing carb amount of
fiber system and the procreation.
So I saw it was somewhere
between three and
five percent and between three and
five percent ten dollars.
How was so so close to zero.
So ten Delta.
Could be an indicator of
the percolation threshold.
So in conclusion
the theoretical model may be
able to predict trickle conductivity for
want of a few material systems.
I know all of them.
And this could be because
of two reasons first.
The theoretical models.
Even the most obvious ones are used a
modified them we are model this not taking
into account all the factors for
example Chris totally Nitty
has been proven to be an important factor
and you've actually called conductive
but not if I mean we are model does
not take into account of that second
there is there's no way to
determine the population's trust so
actually usually the model is
just used to assume value or
like I did just determine
the experimentally and
therefore I'm trying to relate Tendo to
deter me for determining the percolation
Thraso Tendo how approaches zero the
system reaches the percolation threshold.
And lastly there's no
significant relationship
between mechanical properties and
electrical conductivity.
So now I'm working to confirm
the relationship between ten Delta and
percolation thrice so I'm looking for
your creations to calculate ten Delta and
hoping to figure out in direct way
to estimate the percolation threshold and
Mosul experimenting are more material
systems understanding all the factors
that affect you at trickle conductivity.
I would do more for
logical study on the my samples to study
that dispersion is of the re-inforcement
within the matrix and from this point.
I look forward to improve
the existing theoretical models
and I would like to end my presentation
with my acknowledgment page.
I would like to thank you Rob office for
a while to me for summer two thousand A.
And for two thousand and eight and I would
like to stay out of individual list here.
I'm happy to answer any question
the region area
to me for electrical conductivity
in that region.
Yes if we're doing the experiment.
It's really hard to tell what this note
that I went to determine
the percolation thrust hole.
So that's why I want to figure out
a way to determine it without actually
fabricating all the or this somewhat
different loading level is that I have
to go back between like one point five
percent and maybe more sample of this is
ten comes from me and costly one.
Yet you know it much later.
There's a personal health care
large there
this could just be experimental
arrow fabricated my sample.
I thought three samples for
what you stated.
In taking the average and
there just may be something for
you what the facts within the sample but
Ford for
the composite I made those sample
of us are in dark hole or so
I was unable to read it did to
fact within the composite so
that maybe some a few one or
two defected samples.
That's causing a huge i Robot
that this
may be due to the fact that grown
carbon out of fiber so long tubes.
I asked ID injection molding
the pressure was was forced this way and
then it kind of aligned to the fibers
into into a hole reason for that.
Reaction.
So if you have a lot of fibers which
room tubes along these
lines in the directions.
They don't touch each other so
you require more not of the fibers
to actually touch each other to
create a conductive network and
where the carbon black is very cold and
then you can turn that pretty well and
thus requires less reinforcement
withing the polymer matrix to
form that network though
ten donor is a ratio between storage and
loss modulus
wars.
I should put it in.
The art of running force mens' into the
into the composite because more brittle
and approaches zero it's
it's like Norberto so
I'm able to dissipate the energy.
Yes So you if you have Doc told
then you can bet you know if I did.
Despite his faith in you and you get
three point bending the bait I'll pay was
the lacks a factual module is a strength.
So for the ten dollars hard that
I obtain you found a real meter.
So this.
Yeah yeah just as bad as yours.
Look very good thing.
Yeah you know
yeah I think I said I
see a price of a torque
they just like her mind
she says things and
basically ten dollar houses is talking
about energy the material can dissipate so
this no I will be making
making what some health.
Especially photo of a program
coming out of fibers
Where does a big gap between three and
five percent.
Thank you very much.
Thank you.