polymerization is a process of bonding monomer, or "single units" together through a variety of reaction mechanisms to form longer chains named Polymer.

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POLYMERPOLYMER

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Content:Content:
• Historical development.
• What is Polymer ?
• Classification.
• Polymerization.
• Structure & Properties.
- Crystallinity.
- Bulk Properties.
- Glass Transition Temperature.
• References.

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Historical DevelopmentHistorical Development
• Henri Braconnot 1811
• Jons Jakob Berzelius 1833
• BAKELITE 1909
• Joseph Priestly

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What is Polymer?What is Polymer?
• They are complex and giant molecules
and are different from low molecular
weight compounds.
• `Macro-molecules’ are made up of much
smaller molecule.
• Combination of two or more than two
monomers is known as `POLYMER’

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Chains made of interlinked ringsChains made of interlinked rings
(representing polymer molecules)(representing polymer molecules)
Rings of same size
(representing molecules of same
chemical)
Rings of different sizes
(representing molecules of
different chemicals)
Poly meaning `many’ and
mer meaning `part ’( In Greek)
Example:- Butadiene

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Classification of PolymersClassification of Polymers
• Natural and Synthetic Polymers
Natural Polymers Synthetic Polymer
-Cotton -Polyethylene
-silk -PVC
-wool -Nylon
-rubber

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Classification of Polymers continued………Classification of Polymers continued………
• Organic and Inorganic Polymers
A Polymer whose backbone chain is essentially
made of carbon atoms is termed an Organic
polymer.
A Polymer which does not have carbon atom in
their chain backbone is termed as Inorganic
polymer.
Glass and silicone rubber are examples of
inorganic polymer.

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Classification of Polymers continued………Classification of Polymers continued………
•Thermoplastic and Thermosetting
Polymers
Some polymer are soften on heating and can
be converted into any shape that they can
retain on cooling.
Such polymer that soften on heating and stiffen
on cooling are termed as `thermoplastic’
polymer.
Ex. Polyethylene, PVC, nylon, sealing wax
Polymer that become an infusible and insoluble
mass on heating are called `thermosetting’
polymers.

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Classification of Polymers continued………Classification of Polymers continued………
• Plastic, Elastomers, Fibres and Liquid
Resins
A polymer is shaped into hard and tough
utility articles by application of heat and
pressure, it is used as `plastic’. eg. PVC.
When vulcanised into rubbery products
exhibiting good strength and elongation,
polymers are used as `elastomers’. eg.
Natural rubber.

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Plastics, Elastomers, Fibres, and Liquid ResinsPlastics, Elastomers, Fibres, and Liquid Resins
• If drawn into long filament-like
materials, whose length is at least
100 times its diameter, Polymer are
known as `Fibres’. eg. Nylon.
• Polymers used as adhesives, potting
compounds, sealants, etc., in a liquid
from are described as `liquid resins’.
eg. Polysulphide sealants.

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PolymerizationPolymerization
• polymerization is a process of bonding monomer, or
"single units" together through a variety of reaction
mechanisms to form longer chains named Polymer.
• As important as polymers are, they wouldn't exist
without monomers, which are small, single molecules
such as hydrocarbons and amino acids. These monomers
bond together to form polymers. The process by which
these monomers bond is called polymerization
• Polymers such as PVC are generally referred to as
"singular" polymers as they consist of repeated long
chains or structures of the same monomer unit, whereas
polymers that consist of more than one molecule are
referred to as "co-polymers".

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PolymerizationPolymerization
• Polymerization that is not sufficiently moderated and proceeds
at an undesirably fast rate can be very hazardous. This
phenomenon is known as Hazardous polymerization and
can cause fires and explosions.
• Chain polymerization
It is characterized by a self-addition of the monomer molecules
to each other, very rapidly through a chain reaction
• Step polymerization
The polymer build-up proceeds through a reaction between
functional groups of the monomers, the reaction take place in
step wise manner hence it is known as step polymerization

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Polymer Structure & PropertiesPolymer Structure & Properties
• The structural properties of a polymer relate to
the physical arrangement of monomers along the
backbone of the chain.
• Structure has a strong influence on the other
properties of a polymer.
• For example, a linear chain polymer may be
soluble or insoluble in water depending on
whether it is composed of polar monomers (such
as ethylene oxide) or nonpolar monomers (such
as styrene).

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Polymer Structure & PropertiesPolymer Structure & Properties
Monomer identity
• Polymers that contain only a single
type of monomer are known as
homopolymers.
• while polymers containing a mixture of
monomers are known as copolymers.

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Polymer Structure & PropertiesPolymer Structure & Properties
Crystallinity
• Crystalline solids and their behaviour
towards X-rays
* We known that solids are conventionally classified as
crystalline or amorphous, depending on whether they
possess a `long-range order’
* The presence or absence of a long-range order makes
different solids behave differently when exposed to X-
rays.
* while crystalline substance give sharp and well-defined
X-ray diffraction pattern

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Polymer Structure & PropertiesPolymer Structure & Properties
• Polymers and X-ray diffraction
* Polymers diffract X-ray like are crystalline
substance would on the other hand, many behave
like amorphous materials giving very broad and
diffuse X-ray diffraction patterns.
* Unlike simple inorganic compounds.

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Polymer Structure & PropertiesPolymer Structure & Properties
• Effect of crystallinity on the
properties of polymers
1. Density.
2. Hardness.
3. Tensile strength.
4. Permeability

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Polymer Structure & PropertiesPolymer Structure & Properties
• Bulk properties
• The bulk properties of a polymer are
those most often of end-use interest
• These are the properties that dictate
how the polymer actually behaves on a
macroscopic scale

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Polymer Structure & PropertiesPolymer Structure & Properties
•Glass Transition Temperature
• The glass transition temperature, Tg, is the
temperature at which a glass becomes brittle
on cooling, or soft on heating.
• More specifically, it defines a pseudo second
order phase transition in which a supercooled
melt yields, on cooling, a glassy structure and
properties similar to those of crystalline
materials.

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Glass Transition Temperature
• The hard, brittle state is known as the
glassy state and soft flexible state as the
rubbery or viscoelastic state.
GLASSY STATE
(Brittle plastics)
RUBBERY
OR
VISCOELASTIC
STATE
(Tough plastic and
rubbers)
VISCO FLUID
STATE
(Polymer melts)
Tg Tf Temp.
Change of state with temperature in polymeric materials

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Transitions and Associated
Properties
• When a Polymer passes from one state
to another, there is a gradual change
in many of its physical properties.
• When we take a sample of a crystalline
solid in a dilatometer and measure its
volume change with temperature.

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Transitions and Associated
Properties
A
Crystalline solid
C
B
Tm
Liqid
D
0
+
Temperature
Volumechange,

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Specific volume (V) vs
Temperature (T)
• Three polymer sample of the same
chemical structure but different
crystallinity.
• Sample 1-Highly crystalline
• Sample 2-Amorphous
• Sample 3-Partially crystalline

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• Highly crystalline
A B
C
D
Tm
Temp
Crystalline solid
Polymer meltA

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• Amorphous
M
N
Tg Temp
Polymer melt
Rubber
B
Specificvolume(V)
Glassy
solid
O

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• Partially crystalline
T
S
R
Q
P
Tg TmTemp
Glassy and
crystalline solid
Rubber and
crystalline solid
Polymer melt
C

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Glass Transition Temperature
and Plasticisers
• The Plasticiser substantially reduces the
brittleness of many amorphous polymers
because its addition even in small quantities
markedly reduces the Tgof the polymer.
• Their is reduction in Tg with the addition of
different Plasticiser to a polystyrene sample.
• Many Plasticiser such as dibutyl
phthalate,dioctyl sebacate, are used to
decrease the Tg value of PVC.

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Glass Transition Temperature
and Melting Point
• Factors affecting Tg will also affect Tm
based on experimental observation,Tg
and Tm, have been shown to be
interconnected as follow
Tg=1/2 Tm (for symmetrical polymer)
Tg=2/3 Tm (for unsymmetrical polymer)
• Since this relation gives a range for Tg/Tm, it
may more realistically reflect the thermal
behaviour of polymer

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Importance of Glass
Transition Temperature
• Polymeric material
• Used for measuring of evaluating the
flexibility of a polymer molecule.
• Tg value indicate wheather polymer at
the `use temperature’ will behave like
rubber or plastic
• Polymer above Tg will be soft and flexible
and below Tg will hard and brittle.

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ReferencesReferences
• 1) Polymer science, by V. R. Gowariker,
N. V. Viswanathan and Jayadev Sreedhar,
new age international limited publication.
• 2) Pharmaceutical Dosage froms:Disperse
system, volume-3, 2nd
edition by Herbert
A. Lieberman, Martin M. Rieger and
Gilbert S. Banker. Page no:436-438.

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• 3)Biodegradable Polymers as drug
delivery system, Dekker series, edited
by Mark Chasin and Robert Langer. Page
no:3-10,150-155.

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