Polyethylene and its polymerization.pptx

1. Polyethylene
2. Polymerization
3. Classification of Polymers
4. Types of Polymerization
5. Types of polyethylene
6. Manufacturing of LIFE
7. Applications of Polyethylene
8. Addition Polymerization
9. Condensation Polymerization
10. Thermoplastic Polymer
11. Thermosetting Polymer
12. Chain Polymerization
13. Free Radical Polymerization
14. Step growth Polymerization
15. Uses of polyethylene

1. Polyethylene Polymerization Submitted By: Muhammad Razzaq Submitted To: Prof. Dr. Ameer Fawad Zahoor Roll No: 230805

2. Table of Content What is Polymer and Polymerization? Classification Of Polymers Types of Polymerization What is Polyethylene? Types of Polyethylene Manufacturing of LDPE Applications of Polyethylene

3. Polymer A polymer is  any class of natural or synthetic substances composed of very large molecules, called macromolecules, which are multiples of simpler chemical units called monomers . Polymers make up many of the materials in living organisms and are the basis of many minerals and man-made materials

4. Polymerization It is a process by which monomer units are converted into polymers. Polymerization reactions are mostly chain reactions. Examples are polyethene from ethylene, polystyrene from styrene, polyvinyl chloride (PVC) from vinyl chloride, polypropylene from propylene, etc .

5. Classification Based on Source of Origin Based on Structure Based on Mode of Polymerisation Based on Molecular Forces

6. Based on Source of Origin 1. Natural polymers Those polymers which occur in nature. i.e., in plants or animals. are called natural polymers. 2. Synthetic polymers The polymers which are prepared in the laboratory are known as synthetic polymers or man-made polymers, e.g., polythene, synthetic rubber, PVC, nylon-66, teflon , orlon etc. 3. Semisynthetic polymers Polymers obtained by making some modification in natural polymers by artificial means, are known as semi synthetic polymers, e.g., cellulose acetate (rayon), vulcanised rubber etc.

7. Based on Structure 1. Linear polymers These are the polymers in which the monomer units are linked to one another to form long linear chains. These linear chains are closely packed in space. The close packing results in high densities, tensile strength and high melting and boiling points. e.g., high density polyethene, nylon and polyesters are linear polymers.

8. Continue….. 2. Branched chain polymers In such polymers, the monomer units are linked to form long chains with some branched chains of different lengths with source. As a result of branching, these polymers are not closely packed in space. Thus, they have low densities, low tensile strength as well as low melting and boiling points. Some common examples of such polymers are low density polyethene, starch, glycogen etc.

9. Continue…. 3. Cross-linked polymers or network polymers In such polymers, the monomer units are linked together to form three dimensional network. These are expected to be quite hard, rigid and brittle. Examples of cross linked polymers are bakelite , glyptal , melamine-formaldehyde polymer etc.

10. Based on Mode of Polymerisation 1. Addition polymers The polymers formed by the polymerisation of monomers containing double or triple bonds (unsaturated compounds) are called addition polymers. Addition polymers have the same empirical formula as their monomers. Addition polymers can further be classified on the basis of the types of monomers into the following two classes: Homopolymers Copolymers

11. Continue… 2. Condensation polymers The polymers which are formed by the combination of monomers with the elimination of small molecules such as water, alcohol, hydrogen chloride etc., are known as condensation polymers, e.g., nylon 6,6 is formed by the condensation of hexamethylene diamine with adipic acid.

12. Based on Molecular Forces

13. Types of Polymerisation A. Chain Growth Polymerisation or Addition Polymerisation It involves formation of reactive intermediate such as free radical, a carbocation or a carbanion. For this polymerisation monomers used are unsaturated compounds like alkenes; alkadienes and their derivatives. Depending upon the nature of the reactive species involved. chain growth polymerisation occurs by the following mechanisms: 1. Free radical addition polymerisation 2. Cationic polymerisation 3. Anionic polymerisation

14. 1. Free radical addition Polymerisation The monomers used are generally monosubstituted alkenes. The most commonly used catalysts are benzoyl peroxide, hydrogen peroxide or t-butyl peroxide etc. Mechanism The reaction involves the following steps Chain initiation step:

15. Chain propagation step Chain termination step

16. 2. Cationic Polymerisation

17. 3. Anionic Polymerisation

18. B. Step Growth Polymerisation Condensation polymerisation which occurs in a stepwise manner with elimination of some smaller molecules like H2O, NH3, HCI, ROH, etc., is concerned with step growth polymerisation , e.g., adipic acid and hexamethylenediamine phenol and formaldehyde etc., undergo step Growth Polymerisation .

19. Polyethylene

20. Types of Polyethylene  1. Low Density Polyethylene (LDPE) 2. High Density Polyethylene (HDPE) 3. Linear Low Density Polyethylene (LLDPE) 4. Ultrahigh Molecular Weight Polyethylene (UHMW)

21. Continue….. 1. Low Density Polyethylene (LDPE) – First polyethylene produced. - As the name implied, it has a lower density compared to High Density polyethylene. - LDPE has more branching, hence the molecules are less tightly packed and less crystalline due to the side branches. - LDPE is also frequently used in comsumer packaging, bags, bottles, and liners. 2. High Density Polyethylene (HDPE) – It is a polyethylene made from petroleum. - It is sometimes called “ alkathene ” or “polythene” when used for pipes. - HDPE has little branching, giving it stronger intermolecular forces and tensile strength than LDPE. - It is also harder and more opaque and can withstand higher temperatures.

22. Continue…. 3. Linear Low Density Polyethylene (LLDPE) – LLDPE is the most flexible type of polyethylene. - It is a blended form of LDPE where the film has much more flexibility, tensile strength, and more comfortability. - LLDPE is used for films that need a tremendous amount of strength to absorb impacts without tearing or puncturing. 4. Ultrahigh Molecular Weight Polyethylene (UHMWPE, UHMW) – Also known as high-modulus polyethylene (HMPE) or high- performance polyethylene (HPPE). - It is odorless, tasteless and nontoxic. - It has extremely long chains, which results in a very tough material, with the highest impact strength of any thermoplastic presently made.

23. Process Flow of LDPE Production

24. Individual Process Descriptions 1. Demethanization and Deethanization – The feed for the process is a mixture of methane, ethane, and ethylene. Since ethylene is the monomer to be used ethylene has to be separated from methane and ethane. High purity ethylene is used (99.8%).

25. Continue….. 2. Compression of Ethylene and Catalyst Ethylene and the catalyst (free-radical yielding such as oxygen or peroxide) are compressed to operating pressure (150 MPa).

26. Continue…. 3. Solution Polymerization – In a tubular reactor maintained at 190°C, solution polymerization occurs to convert ethylene to polyethylene. About 30% conversion is achieved per pass.

27. Continue…. 4. Pressure Separation – At this stage, the unconverted ethylene is removed and recycled.

28. Continue…. 5. Extrusion and Pelletizing – The polyethylene is extruded and pelletized.

29. Continue….. 6. Quench Cooling – This hardens the polyethylene pellets by addition of cold water.

30. Continue…. 7. Water Separation and Drying – These involve the removal of water from the pellets to obtain the final product.

31. Applications LDPE - Milk, Carton, bowls and buckets, squeezable bottles such as ketchup containers, cable jacketing, flexible water pipes

32. Continue….   2. HDPE- Shopping plastic bags, food packing plastics, crates, dustbin, drums, detergent bottle, , water pipe

33. Continue….. 3. LLDPE- F ood and non-food packaging, extrusion coating applications, garden products, kitchen accessories, luggage and furniture parts, recreational products and toys

34. Continue….. 4. UHMW- Bulletproof vest, vehicular armor joint and ligament reconstruction and spinal and maxillofacial implants.

35. References Organic Chemistry by Dr. Younus CH# 14 (Synthetic polymer) Advance polymer Chemistry by Manas Chanda CH# 1 (Introductory Concepts) https://www.slideshare.net/janapra/polymer-industries https://www.slideshare.net/AlyshaJuguan/polyethylene-78643472