Definition, examples, Process, uses, Advantages and Disadvantages

1. ADDITION
POLYMERIZATION
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2. List Of Contents
 Introduction
 History
 Physical properties
 Mechanism
 Examples & Uses
 Advantages & Disadvantages
 References
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3. INTRODUCTION
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4. POLYMERIZATION-ADDITION POLYMERS
POLYMERS
 A polymers are long chain giant organic molecules
 Formed of many smaller molecules covalently bonded in a repeating pattern
 Primary components of all sorts of plastics and related compound
 Consist of many repeating monomer units in long chain
MONOMERS
 Small molecules containing double bond which make up the polymer are called
monomers.
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5. POLYMERIZATION-ADDITION POLYMERS
ADDITION POLYMERS
 A polymer formed by chain addition reaction between monomer units that are repeatedly
added to form long chain without the elimination of any by product molecules.
 Monomers are usually the derivatives of alkenes
General reaction is :
 n is number of monomers have value in hundred or even thousands (1000-30000)
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6. HISTORY
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7. HISTOR
Y
 The first useful addition polymer was made accidentally
 ICI chemists Reginald Gibson and Eric Fawcett In 1933
 At high temperatures and high pressures
 They set up an experiment to react ethene with benzaldehyde in the hope of producing a
ketone. They left the reaction vessel overnight, and the next morning they found a small
amount of a white waxy solid. It was shown later that this solid was polyethylene.
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8. IUPAC definition
 Chain polymerization: Chain reaction in which the growth of a polymer chain proceeds
exclusively by reaction(s) between monomer(s) and active site(s) on the polymer chain
with regeneration of the active site(s) at the end of each growth step.
 The term "addition polymerization" is deprecated by IUPAC (International Union of Pure
and Applied Chemistry).
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9. PHYSICAL PROPERTIES
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10. Physical Properties OF Addition
Polymers
 The principal characteristics associated with polymers are a consequence of the nature and
covalent arrangement of the monomers units.
 Covalent bonds do not account for most of polymers.
 Weaker intermolecular forces between chains must be considered.
 Hydrogen bonding, electrostatic interactions and van der Waals are believed important
than “weaker” interactions.
 Bonding and nonbonding interactions are important lead to variety of physical
characteristics.
 PVC are sufficiently hard &strong, used in “building materials”.
 Bakelite is hard but is also brittle.
 Polymers such as rubber are known as elastomers.
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11. MECHANISM
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12. Mechanism of Addition Polymerization
The formation of a polymer by addition polymerization is an example of a chain reaction.
Once a chain reaction gets started, it is able to keep itself going. The three steps of this
reaction to focus on are:
 how the reaction gets started (INITIATION)
 how the reaction keeps going (PROPAGATION)
 how the reaction stops (TERMINATION)
 A commonly used mechanism involving a free radical
 Consider an example of polymerization ethylene to form polythene
TYPES OF PEROXIDES USED
 Hydrogen Peroxides H2O2
 Benzoic Peroxides (BPO)
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13. 1-INITIATION
 Initiation take place in two parts
 First Part:
A peroxide molecule breaks up into two reactive free radicals. Light or heat
can provide the energy needed for this process.
 We can write an equation for this process:
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14. INITIATION
 Second Part:
The second part of initiation occurs when the free radical initiator attacks and attaches to
a monomer molecule. This forms a new free radical, which is called the activated monomer.
 We can write an equation for this process, too:
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15. 2-PROPAGATION
In the propagation phase, the newly-formed activated monomer attacks and attaches to
the double bond of another monomer molecule. This addition occurs again and again to make
the long polymer chain.
 we can write an equation for this reaction:
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16. 3-TERMINATION
This chain reaction cannot go on forever. The reaction must terminate. A growing
polymer chain joins with another free radical. We watched a peroxide break up to form two
radicals. It makes sense that two free radicals could join to make a stable bond.
 The equation representing this step of the chain reaction can be written simply as:
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17. OVERALL MECHANISM
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18. EXAMPLES
&
USES
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19. 1-POLYETHENE (Polythene)
 Polyethylene is one of most common polymers, obtained by polymerizing ethylene
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20. Two Varieties of Polyethylene
Low Density Polyethylene
 Abbreviated as LDPE
 Produced at a high pressure (about 2000 atm)
at evaluated temperatures (near 200 C)
 Using oxygen, peroxide and free radical as the
initiator
 Used for thin plastic films and other
packaging materials
High Density Polyethylene
 Abbreviated as HDPE
 Produced at a low pressure (about 7 atm) at
60-70 C
 Ziegler-Natta type catalyst is used
 Used in the manufacture of toys and other
house hold articles
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21. Ziegler-Natta Catalyst
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22. USES OF POLYETHYLENE
 Used to made plastic bottles, plastic bags, toys, house hold articles and harder plastic
objects such as milk crates.
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23. 2-POLYVINYL CHORIDE
 Polyvinyl chloride also known as PVC is formed by addition polymerization of vinyl
chloride (H2C=CHCl)
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24. USES OF PVC
 PVC is a hard resin, and is used to make plastic pipes, rods and compact disc
 PVC is extensively used for plumbing pipes
 Softer PVC is used for imitation leather, plastic coats, floor covering & plastic squeeze
bottles
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25. 3-POLYISOPRENE
 Polyisoprene is a polymer of isoprene and is better known as rubber. It is produced
naturally by rubber trees, but several variants have been developed which demonstrate
improvements on the properties of natural rubber.
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26. 4-POLYPROPYLENE
 Prepared by polymerization of propylene using the Ziegler-Natta type catalyst
 Prepared in isotactic, syndiotactic or atactic form
USES:
 In package films, pipes, storage tanks, seat covers and ropes
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27. 5-POLYSTYRENE
 Polystyrene is also known as polyvinyl benzene, industrially produced by free radical
polymerization of styrene, using the suspension or bulk technique.
 The product is an amorphous, brittle material.
USES:
 In insulation & in molded items
 Used in molded container, lids, jars and bottles
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28. ADVANTAGES
&
DISADVANTAGES
ADDITION POLYMERIZATIONS ARE USUALLY CARRIED OUT IN BULK AND SOLUTION
POLYMERIZATION
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29. Advantages and disadvantages of
Bulk polymerization
ADVANTAGES
 The system is simple and requires thermal insulation
 The polymer is obtained pure
 Large castings may be prepared directly
 Molecular weight distribution can be easily changed with the use of a chain transfer agent
DISADVANTAGES
 Heat transfer and mixing become difficult as the viscosity of reaction mass increases
 The problem of heat transfer is compounded by the highly exothermic nature of free
radical addition polymerization
 The polymerization is obtained with a broad molecular weight distribution due to the
high viscosity and lack of good heat transfer. Very low molecular weights are obtained.
.
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30. Advantages and Disadvantages of solution
polymerization
ADVANTAGES
 Manipulation of polymerization conditions is relatively simple
 Additives can easily be used and there is a broad range of design possibilities. (Various
properties can be achieved.)
 Thin film coating is possible
DISADVANTAGES
 Uses organic solvents
 Requires the use of solvent recovery equipment
 Difficult to use at high concentrations
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31. References
 https://www.answers.com/Q/What_are_the_advantages_and_disadvantages_of_ad
dition_polymerisation
 https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modul
es_(Organic_Chemistry)/Polymers/Addition_Polymers
 https://www.materialsworldmodules.org/resources/polimarization/3-addition.html
 https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_Introd
uctory_Chemistry_(CK-12)/25%3A_Organic_Chemistry/25.19%3A_Polymerization_-
_Addition_Polymers
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