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PolymerPolymer: Maromolecule built-up by the linkingtogether of a large no. of small molecules
Ex. Nucleic acid, paper, bakelite,PVC
Monomer: The small molecule which combine
with each other Mer: The repeat unit
Degree of polymerisation (DP): The no. of
repeating unit(n)Degree ofpolymerisation=Molecular wt of the polymericnetwork/molecular wt of the repeating unit
Depends on degree of polymerisation polymers aretwo types
Oligo polymers:Polymer with low mol.wt
Hi h lo mer: Pol mer with hi h mol. wt
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Polypropylene
mer
Monomer
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Nomenclature of PolymerI. Based on the chemical structure of monomer
i)Homo polymer and ii)copolymer II. Based on the arrangement of monomer in the structu
Homo Polymer:
i)Linear, ii)branched and iii)Cross linked or 3-D polymer
Co polymer:
Linear:i) Regular, ii)Alternating, iii) block and iv)random
copolymer
Branched: Graft copolymer
Cross-linked copolymerIII. Based on atoms in the main chain
i)Homochain polymer and ii)heterochain polymer
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Nomenclature-contdI)Based on the chemical nature of the
monomer units Homopolymer : Identical monomersHomopolymer : Identical monomers
(Polyethylene)(Polyethylene) Copolymer : Monomers with different chemicalCopolymer : Monomers with different chemical
structure (Buna-S: butadiene and styrene)structure (Buna-S: butadiene and styrene)II) Based on structure of polymer chainsII) Based on structure of polymer chains
(Homopolymer &Copolymer)(Homopolymer &Copolymer)
i. Linear homopolymer : - A – A – A – A –i. Linear homopolymer : - A – A – A – A –ii. Branched homopolymer : - A – A – A – A -
A
iii. Cross – linked polymer :- A – A – A – A – A – A – A – A -
- A – A – A – A – A – A – A –
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Linear polymer
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Branched chain polymer
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Cross linked or 3-D polymer-Bakelite
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Copolymers Regular Polymer : Regular
arrangement of monomerunits A&B
Alternating copolymers withregular alternating A and B units
Random copolymers withrandom sequences of monomerA and B
Block copolymers comprised
of two or more homo polymersubunits in long sequenceslinked by covalent bonds
Graft Copolymers are a
special type of branchedcopolymer in which the sidechains are structurally distinctfrom the main chain.
A-A-A-B-A-A-A-B-A-A-A-B
Regular Copolymer
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Nomenclature-contd
III)III. Based on atoms in the main chain
Homochain polymer: Main chain is made up
of same species of atoms
Ex., PVC
ii)heterochain polymer: Main chain is madeup of different atoms
ex.,Nylon 6:6 (mer),
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Copolymer ( Buna-S or SBR)
mer
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Tacticity (Difference in Configuration)Affect their physical properties
Isotactic: Functional gpsor sidegps are all on the sameside:ex., Polypropylene
synthesised using Zielgar Nattacatalyst
Syndiotactic Arrangement of
functional groups or side gps inalternating fashion: Guttapercha-Natural rubber
Atactic: Arrangement offunctional gps or side gpsareat random around the mainchain ex., Polypropylene
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Functionality Number of bonding sites in a monomer
It determines the structure of the polymer.
Three Typee
Bifunctional, trifunctional and polyfunctional11)Bifunctional monomer:Two reactive sites or bonding
sites.
Reactive gp attach side by side to each other forminglinear or straight chain molecule
Monomer units linked by covalent bonds but differentchains are held by van der Waals force
Chain movement in one direction is possible Compound with double bond, amino acid, di-ol etc.,
ex., ethylene glycol, ethylene.
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Functionality -contd
2)Trifunctional monomer: Contains three active sites
Result in branched chain molecule even if it presents in
small amount with bifunctional monomerex.,dimethylol phenol
Movement of chain molecules are restricted due topresence of side chain
3) Containing more than three functional gps.ex.,trimetylol phenol
Monomers are connected to each other by covalent
bonds which results in the formation of 3D networkex., bakelite
The movement of individual molecules are prevented
b stron cross-links
T f P l i ti
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Types of Polymerisation• Addition or Chain polymerisation : Polymer is formed by an
addition reaction, where many monomers bond together viarearrangement of bonds without the loss of any atom or molecule
• Monomers contains one or more double bonds which byintermolecular rearrangement make the polymer which is an exactmultiple of monomer
• Reaction is instigated by the application of heat, light, pressure ora catalyst -break the double bond.
• The polymerisation once initated cannot continue indefinitely as itbecomes difficult to sustain long chain.
• Growth reaction adds repeating units one at a time to the chain
• Ex for Homo polymerisation ; PVC
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Addition or Chain polymerisation • Ex. Homo polymerisation :,Nylon-6: Involves an intramolecular
rearrangement of bonds by opening of cyclic monomer
• Ex. Copolymerization of t wo different monomer:Polybutadiene-co-styrene
mer
Condensation or Step Polymerisation
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Condensation or Step Polymerisation
• Reaction between simple polar gp containing monomers
• Formation of polymer takes place by elimination ofsmall molecules like water, HCl, CH3OH, NH3 etc.,
• An intermolecular combination of monomer.
• When monomers contain three functional gps it may
give cross-linked structure molecule.• Ex.,(Nylon 6,6)
+ 2n H2O
n n
n
a n an con ensa on po ymer sa on
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a n an con ensa on po ymer sa on•Chain polymerisation
•Monomer must have two bonding
sites
•Inter molecular or intramolecular Rearrangement
•Mostly results in homo chain
polymer
•Only growth reaction adds repeatingunits one at a time to the chain
•Number of units decreases steadily
throughout the reaction
•Reaction mixture contains onlymonomer and polymer- no other pdts
•Linear polymer and Thermoplastics
•Mol. Wt of polymer is exact multipleof mol.wt of monomer
•longer reaction time has little effect
on the molecular wt but gives higher
Condensation polymerisation
•Monomer must contain polar group
• Intermolecular combination ofmonomers
•Mostly results in hetero chain polymer
•All types of molecular species present
can react•Monomer disappears early in the
reaction
• All types of molecular species and by
products are present at any stage•Branched and cross-linked polymer-
thermosetting plastics
•Molecular wt is not an exact multiple o
mol.wt of monomer•Moecular mass (DP)rises steadily
throughout the reaction and hence
reaction time is essential
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ClassificationClassification Based on origin:Based on origin:
Natural (Cellulose, Protein, silicone) and syntheticNatural (Cellulose, Protein, silicone) and synthetic(Bakelite)(Bakelite)
Based on StructureBased on Structure
Linear, Branched, 3-dimensional or cross linkedLinear, Branched, 3-dimensional or cross linkedBased on main chain (back bone/ skeleton)Based on main chain (back bone/ skeleton)
i) Homo chain: made up of single type of atom (ex) PEi) Homo chain: made up of single type of atom (ex) PE
ii) Hetero chain: made up of different types of atomsii) Hetero chain: made up of different types of atoms(ex)nylons(ex)nylons
Based on molecular forces (Thermal behaviour)Based on molecular forces (Thermal behaviour)
Thermoplastics, Thermosetting plastics, Fibres, ElastomersThermoplastics, Thermosetting plastics, Fibres, Elastomers
Based on method of synthesisBased on method of synthesis
Addition polymer (eg) PE, PP, PS, nylon 6.Addition polymer (eg) PE, PP, PS, nylon 6.
Condensation polymer (eg)Polyesters , nylon 6,6 Condensation polymer (eg)Polyesters , nylon 6,6
Thermo plastics and Thermosetting plasticsThermo plastics and Thermosetting plastics
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Thermo plastics and Thermosetting plasticsThermo plastics and Thermosetting plasticsThermosetting Plastics
Do not soften; they burnon heating
3-D cross-linked structure
with co-valent bondCondensation polymer
Can not be reshaped
Hard, strong and brittleCannot be reclaimed
Due to strong bonds andcross links they areinsoluble in almost all org.solvents Ex.,Bakelite
Thermo plastics
Soften on heating andharden on cooling reversibly
Long-chain macromolecule
Addition polymerisation
Reshaped, reused
Soft, weak and less brittle
Reclaimed from waste
Soluble in some org.solvents
Ex., PVC
Elastomers and Fibers
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Elastomers and Fibers
Elastomer: Rubber• High elastic properties
• Can be stretched to 4 to 10 times its original
length• Unstressed condition they are not in straigth
chain but in the form of coil
Fibers• Held by strong intermolecular forces like
H-bonding
• Continuous filament ex. Cellulose
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Plastics
Org .materials of high mol.wt, which can be mouldedinto any desired form, when subject to pressure andheat in presence of the catalyst
Resin Basic binding material, a macro molecule (polymer),major parts of the plastics
Undergoes polymerization and condensationduring preparation (Thermosetting plastics).
Mixed with 4-10 ingredients-Compounding
of plastics
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• Classification Plastics
1) Based on usageCommodity plastics
PE, PS , PP, PVC,
Engineering Plastics
Teflon (PTFE) ,PC (Lexan), Polyesters and
Polyamides (Nylon, PET)
2) Based on thermal behaviour
Thermoplsatics
Thermosetting plastics
E i i Pl i
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Engineering PlasticsEngineering Plastics Used to replace conventional materials like metal, wood, glass,Used to replace conventional materials like metal, wood, glass,
ceramics etc.ceramics etc. Used to develop composite articles Used to develop composite articles
CharacteristicsCharacteristics Resistant to corrosion Resistant to corrosion
cast into any desired shape cast into any desired shape light-weight light-weight low thermal coefficient of expansion low thermal coefficient of expansion chemical inertness chemical inertness low melt.pt.low melt.pt. decorative finish decorative finish impermeable to water impermeable to water
low heat resistance low heat resistance
deformation under load,deformation under load, High abrasion resistance High abrasion resistance Dimensional stability Dimensional stability
A li ti
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ApplicationsIn automobile
In defenseElectrical and electronics
Telecommunication
TextileSatellite
Computer components (table top, screen)
RobotsIn aeronautical engineering
Chemical industry
Paper Industry
Adhesives
Lubricants
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