Polymers are large molecules formed by linking many small repeating units called monomers. There are natural polymers like DNA and collagen as well as synthetic polymers like polyethylene, polyvinyl chloride, and nylon. Polymers can be classified based on their structure as linear, branched, or cross-linked, and based on how they are formed as addition or condensation polymers. Properties of polymers depend on factors like chain length, branching, and cross-linking. Common applications of polymers include packaging, insulation, fibers, and medical devices.

1. Polymers

2. Introduction to
Polymers
Poly = many, mer = unit, many units
Polymer science is relatively a new branch of
science . It deals with chemistry physics and
mechanical properties of macromolecule .

3. A polymer is a large molecule which is
formed by repeated linking of the small
molecules called “monomers”.
polymer is organic substance made up of many
repeating units or building blocks of molecules
called ‘monomers’
OR

4. POLYMER
• Combine, many monomers to create a polymer.
• Polymer is often used as a synonym for ‘plastic’.
• All plastic are polymers.
Poly mers are made up of many Mono mer
↓ ↓ ↓ ↓
Many Units One Unit

5. Monomer molecules joined in units of long
polymer.

6. It consist of large no. of repeating units known as monomers
The no. of repeating units in a chain of polymer is known as
degree of polymerization

7. POLYMER
a family of natural and synthetic materials made of repetition of high weight molecules
in a form of flexible chain
NATURAL POLYMER
• Collagen
• Gelatin
• Silk
• Wool
• Natural rubber
• DNA
SYNTHETIC POLYMER
• Polyethylene
terephthalate (PET)
• High Density
Polyethylene (HDPE)
• Polyvinyl Chloride (PVC)
• Low Density
Polyethylene (LPDE)
• Polypropylene (PP)
• Polystyrene (PS)

8. MONOMERS
• The smallest unit of polymer which gets polymerised under certain
conditions to form polymer, called monomers.
• EXAMPLE:
• In the above example Ethene is monomer and Polyethene is
polymer
C C
H
H
H
H
n
ethene
high pressure/trace O2
catalyst
C C
H
H
H
H n
poly(ethene)

9. POLYMERISATION
The process of formation of polymers from respective
monomers is called polymerisation.
EXAMPLE :
C C
H
H
H
H
n
ethene
high pressure/trace O2
catalyst
C C
H
H
H
H n
poly(ethene)

10. Examples Of Polymers
• Polypropylene (PP) - Carpet, upholstery
• Polyethylene low density (LDPE) - Grocery bags
• Polyethylene high density (HDPE) - Detergent bottles, toys
• Poly(vinyl chloride) (PVC) - Piping, decking
• Polystyrene (PS) - Toys, foam
• Polytetrafluoroethylene (PTFE, Teflon) - non-stick pans, electrical insulation
• Poly(methyl methacrylate) (PMMA, Lucite, Plexiglas) - Face shields,
skylights
• Poly(vinyl acetate) (PVAc) - Paints, adhesives
• Polychloroprene (cis + trans) (Neoprene) - Wetsuits

11. Characteristics of Polymers
• Low Density.
• Low coefficient of friction.
• Good corrosion resistance.
• Good mould ability.
• Excellent surface finish can be obtained.
• Can be produced with close dimensional tolerances.
• Economical.
• Poor tensile strength.
• Low mechanical properties.
• Poor temperature resistance.
• Can be produced transparent or in different colours.

12. Properties of Polymers
The physical properties of a polymer, such as its strength
and flexibility depend on:
• Chain length - in general, the longer the chains the stronger
the polymer;
• Side groups - polar side groups give stronger attraction
between polymer chains, making the polymer stronger;
• Branching - straight, un branched chains can pack together
more closely than highly branched chains, giving polymers
that are more crystalline and therefore stronger;
• Cross-linking - if polymer chains are linked together
extensively by covalent bonds, the polymer is harder and
more difficult to melt.

13. Properties of Polymers
• Reflective
• Impact resistant
• Tough
• Brittle
• Translucent
• Malleable
• Soft
• Elastic
• Inelastic
• Insulative

14. Classification
of Polymer is
based on
Source of availability
Structure
Mode of Polymerization
Molecular force
Type of monomers

15. Classification
based on Source
Natural polymers
Semi-synthesis
polymers
Synthesis
polymers

16. Natural polymers
• The definition of a natural polymer is a polymer that results from only
raw materials that are found in nature (plants and animals).
• Example:-
• Starch : It is a polymer of α-D-Glucose
• Cellulose : It is a polymer of β-D-Glucose
• Proteins : It is a polymer of α-Amino acid
• Nucleic acid : It is a polymer of Nucleotide
• Natural Rubber : It is a polymer of Isoprene

17. Semi-synthesis polymers
• Chemically treated polymers of natural origin are quite common and of
great practical importance.
• Cellulose, for example, is used in two different ways:
• it is dissolved using some special solvent and precipitated again in a
different physical shape, e.g.
• viscose silk (Rayon)
• Cellulose acetate used as semi-permeable membrane in RO,s
Chemically treated polymers, that are of
natural origin termed as semi synthesis.

18. Synthesis polymers (Man – Made)
• Synthetic polymers are derived from petroleum oil, and made by
scientists and engineers in laboratories and industries.
• Examples of synthetic polymers include nylon,
• polyethylene,
• polyester,
• Teflon,
• PVC, etc.

19. Based on
structure
Linear polymers
Branched chain
polymers
Cross linked
chain polymer

20. Linear polymers
• Monomeric units are linked together to form long and linear chains.
• They are well packed.
• Due to this they have following properties:
• High densities
• High tensile strenght
• High melting point
• E.g
• High Density Polyethylene (HDPE)
• PVC, Nylon, etc.

21. Branched chain polymers
• Polymers with branches at irregular intervals
along the polymer chain are called branched
polymers
• difficult for the polymer molecules to pack in
a regular array
• Less density.
• Amount and type of branching also affects
physical properties such as viscosity and
elasticity (low)
• Branches often prevent chains from getting
close enough together for intermolecular
forces to work effectively (low tensile
strength)
• E.g. Low density polyethylene(LDPE)

22. Cross linked chain polymers
• These are also called three-dimensional
network polymer.
• Contain strong covalent bonds
• Contain short side chains (cross links)
• Connect different polymer chains into a
“network”
• Adding cross-links between polymer chains
makes the polymer hard, rigid and brittle.
• Example : - Bakelite, Melamine-
formaldehyde resins etc.
Cross links
between chains

23. Based on mode
of polymerization
addition condensation

24. Addition Polymers
• Formed by the direct addition of monomer molecules possessing
double or triple bonds, without the elimination of by product
molecules
• These polymers have same empirical formula as their monomers.
• Example :- Polyethene, PVC, Polystyrene, PAN, Teflon, Natural rubber,
Neoprene, polybutadiene, BuNa-S, BuNa-N, etc.
C C
H
H
H
H
n
ethene
high pressure/trace O2
catalyst
C C
H
H
H
H n
poly(ethene)

25. Condensation polymers
• Formed by condensation reaction between two different bi-functional
monomeric units with the elimination of simple molecules like water
etc. Example :- Terylene (dacron), Nylon-6,6; Nylon-6, Nylon-2,6;
Glyptal etc.

27. Based on
molecular force
Elasromers Fibre Thermoplastic
Thermosetting
plastic

28. Elastomers
• These are rubber – like polymers with elastic properties. In these
elastomeric polymers, the polymer chains are held together by the
weakest intermolecular forces. These weak binding forces permit the
polymer to be stretched.
• A few ‘crosslinks’ are introduced in between the chains, which help
the polymer to retract to its original position after the force is
released as in vulcanised rubber. The examples are BuNa-S, BuNa-N,
Neoprene, etc.

29. Fibres
• Fibres are the thread forming polymers which possess high tensile
strength and high modulus. These characteristics can be attributed to
the strong intermolecular forces like hydrogen bonding between
polymeric chains.
• These strong forces also lead to close packing of chains and thus
impart crystalline nature. The examples are polyamides (Nylon 6, 6),
polyesters (Terylene), PAN (ORLON) etc.

30. Thermoplastic polymers
• These are linear or slightly branched long chain polymers, which can
be softened on heating & reversibly hardened on cooling repeatedly.
• Their hardness is a temporary property & varies with temperature.
• Example:- Polyvinyl chloride, Polyethene, Polystyrene, Teflon

31. Thermosetting polymers
• These polymers are cross linked or heavily branched molecules, which on
heating undergo extensive cross linking in moulds and again become
infusible.
• These cannot be reused and remoulded.
• Some common examples are bakelite, urea-formaldelyde resins, melamine-
formaldehyde resins, etc.

33. Based on type of
monomers
Homo polymers Co-polymers

34. HOMOPOLYMERS
• Consist of chains with identical bonding linkages to each monomer
unit. This usually implies that the polymer is made from all identical
monomer molecules.
• These may be represented as : -[A-A-A-A-A-A]-
• Example : Polyethene, PVC, Polystyrene, Teflon, Polyacrylonitrile,
Polybutadiene, Nylon-6, Natural rubber, Neoprene

35. CO-POLYMERS
• Consist of chains with two or more linkages usually implying two or
more different types of monomer units.
• These may be represented as : -[A-B-A-B-A-B]-
• Example : Nylon-6,6; Nylon-2,6; Terelene; Glyptal; PHBV; Bakelite;
Melamine etc.

36. Applications of Polymers:
AGRICULTURE
Polymeric materials are used in and
on soil to improve aeration, provide
mulch, and promote plant growth
and health.

37. Medicine
• Many biomaterials;
• heart valve replacements
• blood vessels, are made of polymers like Dacron, Teflon and
polyurethane.

38. Consumer Science
• Plastic containers of all shapes and sizes are light weight and
economically less expensive than the more traditional containers.
• Clothing
• floor coverings
• garbage disposal bags
• packaging are other polymer applications.

39. Industry
• Automobile parts
• windshields for fighter planes
• Pipes
• Tanks
• packing materials
• insulation, wood substitutes
• elastomers are all polymer applications used in the industrial market.

40. Sports
• Playground equipment
• various balls
• golf clubs
• swimming pools
• protective helmets are often produced from
polymers.

41. Strength of Polymers
In general, the longer the polymer chain, the stronger the
polymer. There are two reasons for this:
• longer chains are more tangled
• there are more intermolecular forces between the chains
because there are more points of contact. These forces,
however, are quite weak for polyethene.
• Areas in a polymer where the chains are closely packed in a
regular way are said to be crystalline. The percentage of
crystallinity in a polymer is very important in determining its
properties. The more crystalline the polymer, the stronger and
less flexible it becomes.

42. • When a polymer is stretched (cold-drawn), a neck forms. In
the neck the polymer chains line up producing a more
crystalline region. Cold-drawing leads to an increase in
strength.
• The first polyethene which was made contained many chains
which were branched. This resulted in a relatively
disorganised structure of low strength and density. This was
called low density polyethene (LDPE).
• In the crystalline form, the methyl groups all have the same
orientation along the chain. This is called the isotactic
form. In the amorphous form, the methyl groups are
randomly orientated. This is called the atactic form.
• Polymers with a regular structure are said to be
stereoregular.

43. THANKS