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Abstract:
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Combining intrinsically conducting polymers with carbon nanotubes
(CNT) helps in creating composites with superior electrical and thermal
characteristics. These composites are capable of replacing metals and
semiconductors as they possess unique combination of electrical conductivity,
flexibility, stretchability, softness and bio-compatibility. Their potential
for use in various organic devices such as super capacitors, printable
conductors, optoelectronic devices, sensors, actuators, electrochemical
devices, electromagnetic interference shielding, field effect transistors,
LEDs, thermoelectrics etc. makes them excellent substitutes for present day
semiconductors.However, many of these potential applications have not been fully
exploited because of various open–ended challenges. Composites meant for
use in organic devices require highly stable conductivity for the longevity of
the devices. CNT when incorporated at specific proportions, and with
special methods contributes quite positively to this end.The increasing demand for energy and depleting fossil fuel reserves
has broadened the scope for research into alternative energy sources. A
unique and efficient method for harnessing energy is thermoelectric energy
conversion method. Here, heat is converted directly into electricity using a
class of materials known as thermoelectric materials. Though polymers have
low electrical conductivity and thermo power, their low thermal conductivity
favours use as a thermoelectric material. The thermally disconnected, but
electrically connected carrier pathways in CNT/Polymer composites can satisfy the so-called “phonon-glass/electron-crystal” property required for
thermoelectric materials.
Strain sensing is commonly used for monitoring in engineering,
medicine, space or ocean research. Polymeric composites are ideal candidates
for the manufacture of strain sensors. Conducting elastomeric composites
containing CNT are widely used for this application. These CNT/Polymer
composites offer resistance change over a large strain range due to the low
Young‟s modulus and higher elasticity. They are also capable of covering
surfaces with arbitrary curvatures.Due to the high operating frequency and bandwidth of electronic
equipments electromagnetic interference (EMI) has attained the tag of an
„environmental pollutant‟, affecting other electronic devices as well as
living organisms. Among the EMI shielding materials, polymer composites
based on carbon nanotubes show great promise. High strength and stiffness,
extremely high aspect ratio, and good electrical conductivity of CNT make
it a filler of choice for shielding applications. A method for better dispersion,
orientation and connectivity of the CNT in polymer matrix is required to
enhance conductivity and EMI shielding.
This thesis presents a detailed study on the synthesis of functionalised
multiwalled carbon nanotube/polyaniline composites and their application
in electronic devices. The major areas focused include DC conductivity
retention at high temperature, thermoelectric, strain sensing and electromagnetic
interference shielding properties, thermogravimetric, dynamic mechanical
and tensile analysis in addition to structural and morphological studies. |