Transcript Document

Xth International Seminar on Inclusion Compounds (ISIC–10) September 19–23, 2005 Kazan, Russia
The device for the measurement of conductivity of
polymer microfibers
T.E. Osmanov, I.V. Yaminsky
Faculty of Physics, MSU, Leninskie gory, Moscow, Russia & Institute of Organoelement
Compounds, RAS, Moscow, Russia.E-mail: [email protected]
Summary Electric properties of polymer micro and nanofibers are practically not investigated. Such fibers are
characterized by a high surface/volume ratio. They reveal good abilities to adsorb low-molecular substances. Composite fibers
with metal inclusions are of special interest for the catalysis chemistry.
Materials
Device
Polyacrylnitril (PAN) fiber
with diameter from 20 up
to 40 nanometers (Fig.1.)
Fig.2. Picture of
Polyacrylnytryl
fibres made by
electron microscope.
Fig.4. Container with
sample. Also on this
figure you can
observe termistor,
special magnets for
holding the sample
and holes for
sorbate.
Fig.5. Measurement of
electrical noise. Currentvoltage relation.
We have constructed a precise device
for the measurement of electric
resistance of polymeric fibers. It is
based on the FemtoScan scanning
probe microscope and reveals several
advantages:
experiments can be
performed
in
the
environmental
chamber using different adsorbates and
at
various
temperatures.
The
temperature inside the chamber is
controlled by thermistor, which acts
also as a heater. The device allows to
observe adsorption of different gases
by the microfiber and to find its
dependency upon temperature.
Fig.3. Scheme of the
device. 1 operational amplifier
and container with
sample, 2- digital-toanalog converter and
analog-to-digital
converter, 3 - DSPcard, 4 – server and
client computers
The dependence of the conductivity of PAN upon
temperature and humidity of air is found; irreversible
changes of a fiber conductivity are registered during the
electrical current passage
Temperature (time)
The device can measure the resistance of fibers with
accuracy 0.5%, i.e. 20-100 Om depending on fiber
resistance.
Fig.6. The change of electrical
conductivity with temperature in
open atmosphere. Temperature
varies from 20 to 60 degrees
centigrade. Resistance varies from
2750 to 3860 Om.
Fig.7. Current-voltage relation
of Polyacrylnitril fiber.
Conclusion The application of the device for the
studying gas-hydrates is proposed. It is possible to watch
for adsorption by tracing changes of electrical resistance.
The device can be used as a main part of the chemical
sensor for the measurements of adsorption.
The support of the Russian Foundation for Basic
Research (project N 04-03-32472) and Russian
Academy of Sciences (Program “Chemistry and
physchemistry of supramolecular systems and atomic
clusters”) is acknowledged.