Downloaded 38 times
Uploaded byRamsha Afzal
Addition polymerization, its examples and uses
Addition polymerization involves monomers joining together through a chain reaction without producing any byproducts. Common addition polymers include polyethylene, polyvinyl chloride, polyisoprene, polypropylene, and polystyrene. Addition polymerization can occur through bulk or solution polymerization. Bulk polymerization uses only the monomers while solution polymerization uses a solvent. Both methods have advantages like control over molecular weight but also disadvantages like poor heat transfer during bulk polymerization.
More Related Content
Similar to Addition polymerization, its examples and uses
Addition polymerization, its examples and uses
- 1.
- 2. List Of Contents Introduction History Physical properties Mechanism Examples & Uses Advantages & Disadvantages References 2
- 3.
- 4. POLYMERIZATION-ADDITION POLYMERS POLYMERS Apolymers 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. 4
- 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) 5
- 6.
- 7. HISTOR Y The firstuseful 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. 7
- 8. IUPAC definition Chainpolymerization: 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). 8
- 9.
- 10. Physical Properties OFAddition 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. 10
- 11.
- 12. Mechanism of AdditionPolymerization 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) 12
- 13. 1-INITIATION Initiation takeplace 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: 13
- 14. INITIATION Second Part: Thesecond 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: 14
- 15. 2-PROPAGATION In the propagationphase, 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: 15
- 16. 3-TERMINATION This chain reactioncannot 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: 16
- 17.
- 18.
- 19. 1-POLYETHENE (Polythene) Polyethyleneis one of most common polymers, obtained by polymerizing ethylene 19
- 20. Two Varieties ofPolyethylene 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 20
- 21.
- 22. USES OF POLYETHYLENE Used to made plastic bottles, plastic bags, toys, house hold articles and harder plastic objects such as milk crates. 22
- 23. 2-POLYVINYL CHORIDE Polyvinylchloride also known as PVC is formed by addition polymerization of vinyl chloride (H2C=CHCl) 23
- 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 24
- 25. 3-POLYISOPRENE Polyisoprene isa 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. 25
- 26. 4-POLYPROPYLENE Prepared bypolymerization 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 26
- 27. 5-POLYSTYRENE Polystyrene isalso 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 27
- 28. ADVANTAGES & DISADVANTAGES ADDITION POLYMERIZATIONS AREUSUALLY CARRIED OUT IN BULK AND SOLUTION POLYMERIZATION 28
- 29. Advantages and disadvantagesof 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. . 29
- 30. Advantages and Disadvantagesof 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 30
- 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 31