cunducting plastics for dpt vth sem

8/3/2019 Cunducting Plastics for dpt vth sem

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Introduction to

Conducting Plastics

Md Mohsin Alam


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Md Mohsin Alam

Plastics are one of the most used materials in themodern world.

Their uses and application range from containers toclothing.They are used to coat metal wires to preventelectric shocks.

Introduction


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Until 3 decades ago, all carbon based plastics wereregarded as electrically non-conducting. However

spectacular development in the science andtechnology of synthetic polymer research, saw theemergence of electrical conductivity as a valuedproperty in plastics


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Alan Heeger Alan MacDiarmid Hideki Shirakawa

Break through given

by


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Application

Coaxial Cable PANI would replace copper in braided parts of cable.


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Application

Electromagnetic Shielding

Thin films of conducting plasticsprevent electromagneticradiations emitted fromcomputer which affects near byelectrical parts


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Application

Flexible Display Photoconducting Plastics used which would replaceLC display


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Application

Batteries Light weight rechargeable batteries.


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Application

Artificial Muscles Current area of research


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Application

Biological Sensor Sensors for aroma, enzymes andpesticides (change conductivity with redox agents)


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Application

Camouflage Coating Spoof radars by absorbing the radarsignals


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Application


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Application

Drug Delivery Controlled drug delivery purpose


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Conductivity can be defined simply by Ohms Law.

V= IRWhere R is the resistance, I the current and V the voltagepresent in the material. Thus from this relationship

conductivity is found The conductivity depends on thenumber of charge carriers (number of electrons) in the

material and their mobility.

What is conductivity?


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Types of conducting plastics

Electrically conducting plastics

Ionically conducting plastics

Photoconducting plastics


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Structure of conducting plastics


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Structure of conducting plastics


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How conduction in plastics ?

The structure of all electrically conducting plasticsare characterized by presence of p-bonds which

when conjugated can delocalize over all the atoms.

But conduction by nature is very low in

plastics


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How to increase conduction ?

Answer : Through Doping process


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Doping is either the addition of electrons (reductionreaction) or the removal of electrons (oxidation reaction)

from the plastics. Once doping has occurred, theelectrons in the pi-bonds are able to "jump" around thepolymer chain. As the electrons are moving along themolecule a electric current occurs.

Doping


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However the conductivity of the material is limited asthe electrons have to "jump" across molecules so for

better conductivity the molecules must be well orderedand closely packed to limit the distance "jumped" by theelectrons. By doping, the conductivity of the polymerincreases from 10-3 S m-1 to 3000 S m-1.


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Processing Conducting Plastics

Cannot be conventionally processed.

Processed through special technique called solutioncasting. Polymer dissolved in solvent and appliedover an substrate. Solvent evaporated and film

formed recovered.

cunducting plastics for dpt vth sem

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