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www.materialsresearchlab.netSHARDA UNIVERSITY

PHY303-Smart Materials & PHY303-Smart Materials & DevicesDevices PHY303-Smart Materials & PHY303-Smart Materials & DevicesDevices

http://pramodkumarsingh.weebly.com

SBSR, Sharda University, G. Noida, IndiaE mail: [email protected]

Ph. No. :+91-9971729840


Polymer based NanocompositePolymer based Nanocomposite

*Polymer

+

*Nano composite


Polymer

* Polymer (Greek Poly & Meros /part) is a large molecule (macromolecule)

* composed of repeating structural units typically connected by covalent chemical bonds.


CLASSIFICATION OF POLYMERS

Classification on the basis of origin:1.NATURAL POLYMERS: ex:Silk, Cellulose

2.DERIVED POLYMERS: derived from natural Polymers ex: cellulose acetate, artificial silk. 3.SYNTHETIC POLYMERS: Synthesis of one or more than one chemical units of low molecular weight ex:PVC,PVA.


1.HOMOCHAIN POLYMERS:Ex:Polyethylene is a homopolymer.

2.HETEROCHAIN POLYMERS:Ex:Polyethylene adipate.

CLASSIFICATION OF POLYMERSChain structure:


1.LINEAR POLYMERS: molecules are linked in the form of chain.

2.BRANCHED POLYMERS:Molecules having a branched structure.

3.CROSS LINKED POLYMERS: Branches that connect polymer chains.

4.GLOBULAR /SHEET POLYMERS: It contain 2/3-D molecules. Ex:Bakellite.

CLASSIFICATION OF POLYMERS

Chain Structure:


On the basis of Processing behaviour:

1.THERMOPLASTICS: Polymers that can be heat-softened into a desired form and shape.

Ex: Polyethylene, Polypropylene, PVC.

2.THERMOSET POLYMERS: Initially as liquid,on heating form highly cross-linked solid polymers.

Ex: Alkyds, Amino,Polyurethanes.

CLASSIFICATION OF POLYMERS (Processing Behavior)


On the basis of Polymerization Mechanism:

CONDENSATION POLYMERS:Small loss of water or other simple molecule like NH3,HCl,NaCl.etc.

Ex:Polyesters,Terylene..etc.

ADDITION POLYMERS:Monomers are added involving some kind of active centres.

such as free radicals,cations or anions.

CLASSIFICATION OF POLYMERS (Polymerization Mechanism)


On the basis of Forms and Application:

PLASTICS: Shaped into hard and tough articles by heat and pressure.

Ex: Polystyrene, PVC

Elastomers: Vulcanized into rubbery products, exhibit good strength and elongation. Ex: Polyisoprene, Silicone rubber.

Fibres: Drawn into long filament, length more than 100times its diameter.

Ex: Polyamides, Polyesters.

Resins: Used as an adhesive, sealants in a liquid form.

Ex: Eepoxy adhesives, Poly sulphide sealants.

CLASSIFICATION OF POLYMERS (Forms & Application)


Classification of Polymer (Conduction behavior)

Macromolecules formed by the repetition of a small unit (monomers)

Classified as

*Insulating Polymers

*Semi conducting Polymers

*Ion Conducting Polymers

or Polymer Electrolytes


Polymer Electrolytes

Classified as

* Polyelectrolyte

* Solvent Swollen Polymers

* Solvent Free Polymer Salt Complex


Polymer ElectrolytesPolyelectrolytes:

consisting of their Own Ion Generating Group which is chemically attached to the main chain of polymers. The σ is very low in “Dry State”(10-12 to 10-15 S/cm.) but Hydrated NAFION has σ very high (10-2 S/cm.)

Solvent Swollen Polymers:

Some solvent swell in the host matrix like PVA,PVP and dopant ionic solute (like KOH, H3PO4) can be accommodated in

the Swollen Region. Swollen region which is solvent rich allow ionic motion.

PVA+H3PO4 σ 10-5 S/cm. Polak et al; 1989

Solvent Free Polymer-Salt Complex:

Form of thin film → Solution Cast Tech.→ Solution of Polymers

& Salts → Mixed/Stirred → Casted into Petridishes → Evaporation

of Solvent → Solvent Free Polymer electrolyte Film


Kevlar (Polymer Fiber)

• Registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora.

• Developed by Stephanie Kwolek at DuPont in 1965*

• Commercially used in the early 1970s as a replacement for steel in racing tires


Kevlar (poly paraphenylene terephthalamide)

• 5 times stronger than steel on an equal weight basis

• 1964, her group began searching for a new lightweight strong fiber to use for light but strong tires

• Polymers she had been working with at the time, poly-p-Phenylene-terephthalate and polybenzamide

Stephanie Kwolek



• Formed liquid crystal while in solution

• The solution was “Cloudy, opalescent upon being stirred, and of low viscosity" and usually was thrown away.

• Charles Smullen, who ran the "spinneret", to test her solution, and was amazed to find that the fiber did not break, unlike nylon

• Spinneret (polymers), a device used to extrude polymers into fibers

Stephanie Kwolek



• Her supervisor and her laboratory director understood the significance of her accidental discovery and a new field of polymer chemistry

• By 1971, modern Kevlar was introduced

Stephanie Kwolek


Kevlar (Polymer Fiber) Kevlar is synthesized in *Solution from the monomers 1,4-phenylene-diamine & terephthaloyl chloride in a condensation reaction yielding hydrochloric acid as a byproduct.

*Production is expensive because of the difficulties arising in synthesis &spinning


Graded of Kevlar

• Kevlar K-29 – in industrial applications, such as cables, brake linings, and body/vehicle armor.

• Kevlar K49 – high modulus used in cable and rope products.

• Kevlar K100 – colored version of Kevlar

• Kevlar K119 – higher-elongation, flexible and more fatigue resistant.

• Kevlar K129 – higher tenacity for ballistic applications.

• Kevlar KM2– enhanced ballistic resistance for armor applications[


Structure & Properties*Kevlar is spun, the resulting fiber has a tensile strength of about 3,620 MPa,

Relative density of 1.44.

The polymer owes its high strength to the many inter-chain bonds. These inter-molecular hydrogen bonds form between the carbonyl groups and NH centers.

Kevlar's structure consists of relatively rigid molecules which tend to form mostly planar sheet-like structures rather like silk protein


Preparation (Polymer Nano Composites)


Infrared Spectroscopy (to check complex formation & composite formation)

The IR of Complexed PEO does not contain the specific bands of NH4I

located exactly at the same wavenumber

i.e complexation is complete and

no unreacted NH4I remains

☞ Shifting of peaks positions

☞ No new peaks

*NH4I has complexed with PEO to

form a polymer electrolyte.

*Composite


15 20 25 30 35 40

Inte

ns

ity

2 theta

PEO/KI/I2/IL80wt% PEO/KI/I2 I2 KI

a

b

c

d

XRD

• complete complexation

• reduced in crystallinity

no additional peaks of KI in c


Industrial Application of Polymers

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