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CLASS-XII
CHEMISTRY
POLYMERS
PREPARED BY A .P SINGH
PGT CHEMISTRY
JNV ERNAKULAM
1.Introduction
2.Classification of Polymers .
3.Mechanism of Polymerisation
4.Preparation of polymers
5.Coplymerisation
6.Natural and Synthetic Rubber
7.Biodegradable polymers
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POLY
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Mer
Polymer
Many
Units
Definition
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Classification of polymer
Source
Structure
Molecular Forces
Based on
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Classification of polymer
Source
Based on
Natural
Semi-synthetic
Synthetic
Proteins, Cellulose, Starch.
Rayon, Cellulose nitrate, Cellulose acetate
Nylon-6,6, Polyester, Polythene
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Classification of polymer
Structure
Based on
Linear
Branched Chain
Cross-Linked
PVC
HDPE
LDPE
Bakelite
Melamine
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Classification of polymer
Molecular Forces
Based on
e.g. Buna-S,Buna-N, Rubber, Neoprene.
3. Thermoplastic: Slightly branched, soft on heating and hard on cooling. e.g. polythene, Polystyrene ,PVC etc.
2. Fibres: Strong Intermolecular forces, like Hydrogen bonding. e.g. Nylon 6,6, Polyesters(Terylene) etc.
4. Thermosetting: Cross linked, heavily branched.
e.g. Bakelite, Melamine
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TYPES OF POLYMERISATION REACTIONS
Addition Polymerisation
Unsaturated Monomer undergo polymerization.
Examples:
Polythene
Polypropene
Buna-S
Condensation Polymerisation
Bi-Functional monomer undergo polymerization.
Examples
Nylon-6,6
Polyester
Bakelite
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Addition polymerisation or
Chain Growth Polymerisation
Molecules of same monomer or different monomers add together on a large scale to form polymer. The monomers are unsaturated compounds eg : alkenes and their derivatives, alkadienes and their derivatives.
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1) -T E F L O N
Teflon is manufactured by heating tetrafluroethene with a free radical or persulphate catalyst at high pressure
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(2)- POLYACRYLONITRILE, ORLON, ACRILAN
Acrylonitrile undergo polymerisation in presence of peroxide catalyst give polyacrylonitrile and it is used in making commercial fibres.
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3-POLYTHENE
TWO TYPES OF POLYTHENE
1 LOW DENSITY POLYTHENE(LDPE)
It is obtained by the polymerisation of ethene at 1000-2000 atm and 350-570 K in presence of trace of dioxygen or peroxide initiator(catalyst). It is used in the insulation of electric wire , manufacture of squeeze bottles, toys, and flexible pipes.
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2 HIGH DENSITY POLYTHENE(HDPE)
It is obtained when addition polymerisation of ethene takes place in a hydrocarbon solvent in the presence of Zigler –Natta Cattlyst ( Triethylaluminium and titanium tetrachloride ) at 333-343K and 6-7 atm.It has high density due to close packing.It is chemically inert and more tougher and harder.It is used for making buckets, dustbins, bottles, pipes etc.
Mechanism of Addition Polymerisation
Free Radical Mechanism
1. Chain Initiation Process
Mechanism of Addition Polymerisation
Free Radical Mechanism
1. Chain propagating Step
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3. Chain Terminating Step
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Condensation Polymerisation or step growth polymerisation
It involves a repetitive condensation reaction between two bi-functional monomers with the loss of some simple molecule like water,alcohol etc. In this reaction product of each step is again bi- functional . Since each step produce distinct species ,this is also called step growth polymerisation.
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(1) POLYAMIDES
1 NYLON 6,6---
It is prepared by the condensation polymerisation of hexamethylenediamine with adipic acid under high pressure and temperature. It is used in making sheets , bristles of brushes and in textile industry.
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Nylon 6 is used for the manufacture of tyre cords , fabrics and ropes .
2-NYLON-6
It is obtained by heating caprolactum with water at high temperature
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2 POLYESTERS OR
TERYLENE OR DACRON
It is formed by the interaction of ethylene glycol and terephthalic acid
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3 PHENOL FORMALDEHYDE POLYMER(BAKELITE)
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Difference
S.N. | Addition Polymerisation | Condensation Polymerisation |
1. | Monomers are unsaturated. | Monomers are bi-fumctional |
2. | Initiator required. | Initiator not required. |
3. | No byproduct form in this process. | Small molecules like water, alcohol forms. |
4. | Also known as Chain growth polymerization. | Also known as Step growth polymerization. |
5. | Example: Polythene, Polypropene… | Example: Nylon, Bakelite etc. |
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Homopolymer: Monomers are of One Kind.
Example: Polythene, PVC, Teflon etc..
Copolymer: Monomers are of different kind.
Example: Buna-N, Buna-S, Nylon-6,6.
Homopolymer and Copolymer
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Buna-S
Copolymerisation –
It is union of different monomers
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Natural Rubber
Polymerisation
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Biodegradable Polymer
PHBV (Poly-β-hydroxybutyrate-c0-β-hydroxyvalerate)
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Nylon 2 –nylon 6
It is the copolymer of glycine and amino caproic acid
NH2CH2COOH + NH2 (CH2)5 COOH =
( ---NH-CH2 CO-NH-(CH2)5-CO--)n
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Name of polymer | Monomer | Structure of monomer | Uses |
1.Poly tetra fluoro ethene | Tetra fluoro ethene | CF2=CF2 | Non stick surface coated utensils |
2.Polyacrylonitrile | Acrylonitrile | CH2=CHCN | Substitute for wool making , orlon, acrilan |
3.Nylon 6,6 | Hexamethylenediamine Adipic acid | H2N-(CH2)6-NH2 , HOOC-(CH2)4-COOH | Making sheets, bristles for brushes, intextile industry |
4.Nylon 6 | Caprolactum | -CO-(CH2)5-NH- | Tyrecords,fabrics& ropes |
5.Polystyrene | Styrene | C6H5-CH=CH2 | An insulator, wrapping material, manufacture of toys |
6.Polyvinyl chloride | Vinylchloride | CH2=CHCl | Rain coats, handbags, vinylflooring |
Some important polymers their monomers & uses
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Name of polymer | Monomer | Structure of monomer | Uses |
7.Urea-formaldehyde resin | Urea,formaldehyde | NH2-CO-NH2 , HCHO | For making unbreakable cups& laminated sheets |
8.Bakelite | Phenol,formaldehyde | C6H5OH,HCHO | For making comb,electrical switches,handles ofutensils |
9.Buna-N | 1,3Butadiene,acrylonitrile | CH2=CH-CH=CH2 CH2=CHCN | Making oil seals,tank lining |
10.Buna-S | 1,3Butadiene, Styrene | CH2=CH-CH=CH2, C6H5-CH=CH2 | Manufacture of autotyres, floortiles,cable insulation |
11.Neoprene | Chloroprene | CH2=CCl-CH=CH2 | Manufacturing conveyor belts,gaskets&hoses |
12.PHBV | 3Hydroxybutanoic acid 3Hydroxypentanoic acid | CH3CH(OH)CH2COOH CH3CH2CH(OH)CH2COOH | Speciality packaging, orthopaedic devices |
Some important polymers their monomers & uses
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IMAGES OF POLYMERS
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https://youtu.be/OxdJlS0xZ0Y
VIDEO POLYMER
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Thanks..