Polumers-Dr. Surendran Parambadath


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Polumers-Dr. Surendran Parambadath

  1. 1. Dr. SURENDRAN PARAMBADATH (M.Sc, M.Phil, M.Tech) Formerly: Post Doctoral Research Associate,Nano-Information Materials Research Laboratory, Pusan National University, Busan-South Korea Currently: Assistant Professor Govt. Polytechnic College, Perinthalmanna
  2. 2. What is a polymer? • A long molecule made up from lots of small molecule called monomers.
  3. 3. Poly = many, Mer = unitMacromolecules: If the compound containing hundreds orthousands of atoms per molecule are called macromecules.Eg: Starch, Cellulose, proteins, nucleic acids, rubber, silk etc.The repeating unit in the molecule is called monomer.Polymers consisting of a single type of monomer molecules areknown as homopolymers.The polymers obtained from monomers of different types arecalled copolymers.
  4. 4. Homopolymer -A-A-A-A-A-A-A-A-Example: Polythene, nylone-6, Polystyrene, Polyvinyl chloride(PVC)Formation of homopolymer………………
  5. 5. Copolymer -A-B-A-B-A-B-A-B-A-B-Example: Nylone-6.6, Styrene-butadiene rubber (SBR), Buna-S,Bakelite.Formation of Copolymer…………………
  6. 6. POLYMERIZATIONIt is the process of chemical combination of two or moresmaller and simpler molecules of similar or different types,with or without the elimination of small molecules like H2O,HCl or C2H5OH, resulting in the formation of new C-C or C-Nlinkages in the product.Example:Polythene from etheneNylone-6 from caprolactumBuna-S from Butadiene and styreneNylone-6,6 from Hexamethylene diamine and adipic acid with eliminationof H2O.
  7. 7. Polymerization is of two types1. Addition polymerization2. Condensation polymerization
  8. 8. 1. Addition polymerizationIn this type of polymerization, the polymer formed in an exactmultiple of monomer molecules and there is no elimination.This polymerization may initiate by heat or pressure.nCH2=CH2 -(-CH2-CH2-)- Ethylene Polyethylene
  9. 9. 2. Condensation polymerizationIn this type of polymerization, chain growth takes place together withelimination of small molecules like water, ammonia, alcohol etc.This polymerization may initiate by heat or pressure.HO-CH2-CH2-OH + HOOC-C6H4-COOH Ethylene Glycole 1,4-dibenzoic acid -H2O -{-O-CH2-CH2O-CO-C6H4-CO-}-
  10. 10. No Addition Polymerization Condensation Polymerization1 Formed by the simple addition In this process two or more of monomers with out liberation monomers will combine together of small molecules. with the liberation of some simple molecules.2 Monomers usually contains Monomers contain two functional double or triple bond groups.3 The monomers and polymers The monomers and polymers having the same empirical having the different empirical formula. formula.4 Most of them asre formed by Most of them are formed by step chain growth polymerization. growth polymerization.
  11. 11. 1 Based upon Natural and synthetic polymers source2 Based upon Addition and condensation polymers synthesis3 Based upon Inorganic and organic polymers elements4 Based upon Plastic: Intermolecular forces of attraction are molecular intermediate between those of elastomers and forces. fibers. Elastomers: Chains are held together by weak forces Fibers: Held together by strong inter molecular forces.
  12. 12. Elastomer Fibre Plastic
  13. 13. A plastic is a material which shows theproperty of plasticity ie, capacity to change todifferent forms under pressure.Plastics may be defined as organic material ofhigh molecular mass, which can be mouldedinto any desired shape, by subjecting tosuitable heat and pressure conditions inpresence of a catalysts.
  14. 14. • No cross links between chains.• Weak attractive forces between chains broken by warming.• Change shape - can be remoulded.• Weak forces reform in new shape when cold.
  15. 15. • Extensive cross-linking formed by covalent bonds.• Bonds prevent chains moving relative to each other.
  16. 16. Thermoplastics Thermosetting Plastic1 They have formed by addition They have formed by condensation polymerization and usually have polymerization and usually have three linear structure dimensional extensive cross linking between the polymer chains.2 They are soft, weak and less They are more hard, strong brittle and brittle and are soluble in organic insoluble in organic solvents. solvents3 Can be remoulded, recast Cannot be remoulded or reshaped. reshaped, and reused by Once set, it cannot be recast by any application of suitable pressure means. and temperature.4 On heating they soften and On heating, do not soften, rather they become fluid but on cooling become hard and infusible, prolonged become hard. heating make them burn.5 Eg. Cellulose acetate, PVC, Bakelite, polyester, terylene, resins, Polythene, Polypropylene, Teflon urea-formaldehyde polymer ect. etc.
  17. 17. 1 Light weight, but tough very good tensile strength, high dimensional stability and high refractive index.2 Low thermal and electrical conductance and high insulating power, low thermal expansion-coefficient, very good shock absorption capacity.3 Resistance to corrosion and rust, to abrasion, to growth of fungus and insects, action of fumes, gases and corrosive substances.4 Chemical inertness to acids, oils, dampness, light etc.5 Capability of being made (a) hard or soft (b) rigid or pliable © tough or fragile (d) opaque or transparent (e) brittle or malleable or elastic (f) wearable, curvable or pourable.6 Easy workability, ability to take variety of fast and appealing colors, shades. Shining glossy appearance etc.7 Low fabrication cost and low maintenance cost.
  18. 18. 1.Higher cost and combustibility2.Poor ductility3.Softness and deformation under load4.Brittleness at low temperature5.Low heat resistance6.Non biodegradable7.Not easy to dispose off.
  19. 19. Elastomers include all those polymers, whose chains are heldtogether by weak forces and hence can be stretched by pullingand on relieving the stress, can be made to regain their originalshape.Eg: Rubber
  20. 20. Natural RubberDestructive, distillation of rubber from the tree gives ahydrocarbon C5H8 isoprene-(2-methyl-1,3-butadiene) which isthe repeating unit in rubber. Rubber contains 16000-20000 unitsin one string.
  21. 21. VulcanizationIt is the process of heating natural rubber with sulphur (3-5%),H2S, benzoyl chloride to a temperature range 110-140oC.Merits of Vulcanization1. It helps in preventing the slippage of chains on application of stress.2. It makes rubber less sensitive to temperature changes.3. It increases elasticity, tensile strength and extensibility.4. It increases the resistance of rubber to oxidation, abrasion, wear and tear, water and organic solvents.5. Rubber becomes a better electrical insulator as a result of vulcanization
  22. 22. Applications of Rubber 1. For making rubber bands, golf balls, mechanical rubber goods, rubber gaskets for sealing equipments like pressure cooker, refrigerators doors etc. 2. For making automobile and aeroplane tyres due to its abrasion resistance. 3. In telephone receivers, battery cases, electrical switch board panels etc. 4. Due to its remarkable resistance to electricity used for insulating coating on wires and cables. 5. In medicine, rubber is used for making heart valves, transfusion tubings, padding for plastic surgery etc. 6. It finds uses as an eraser and adhesive too.
  23. 23. Synthetic Rubber These are man made, rubber like polymer……………… Eg: Buna-S, Thiokol, Buna-N Name Uses 1 Buna-S Manufacture of motor tyres, floor tiles, gaskets, wire & cable insulation. 2 Buna-N Conveyer belts, high altitude air craft components, hoses printing rollers, automobile parts. 3 Neoprene Wire insulations, cable covering for conveyer belts and chemical apparatus, sponges etc. 4 Butyl Rubber Cycle and automobiles parts, tank linings 5 Thiokol Hoses, gaskets and covering for cables. 6 Silicon rubber Artificial heart valves, transfusion tubes and padding for plastic surgery, in lubricants, paints and protective coatings, shoes.
  24. 24. Fibres are thread like bits of materials characterized bygreat tensile strength in the direction of the fibre.Cloths are making from fibres.Types of Fibre……………..1. Natural fibre, obtained from natural sources like cotton, jute, wool and silk.2. Semi synthetic fibres, obtained from natural sources eg: cellulose, which is heated with special reagents to bring it to solution or dispersed state and then turned into filaments Eg: Rayons.3. Synthetic fibres, obtained by addition or condensation polymerization. Eg: Nylon, terylene, orlon etc.
  25. 25. A fibre may be defined as aflexible macroscopicallyhomo-geneous body of high tensilestrength, possessing a highratio of length to thicknessand a small cross section.
  26. 26. The main characteristics of a fibre forming polymer are, 1 Should be convertible to a dissolved form and then spun into fine fabric. 2 Should posses high tensile strength to produce stable fibre. 3 Should have sufficient resistance to light, heat and air-oxidation. 4 Should be able to take fast colours.
  27. 27. Nylon 6,6It is formed by the condensation polymerisation of adipic acidand hexamethylene diamine.It is a polyamide polymer. n HOOC-(CH2)4- + n H2N-(CH2)6-NH2 COOH Adipic acid Hexamethylene diamine O -[-OC-(CH-C-NH-(CH6-NH- 2)4 2) + n H2O ]n-Nulon-6,6 is stronger than natural fibres. They are elastic, lightweight, very strong and flexible, inert to chemicals and biologicalagents and are used in making fabrics, carpets, tyre cords, ropes etc.
  28. 28. Nylon 6It is manufactured by prolonged heating of caprolactum at 260-270oC.It is another polyamide polymer. H N OCH2 C=O 260-270oC -[ -C-NH-(CH5-]n- 2)CH2 CH2 C C H2 H2 Caprolactum Nylon 6
  29. 29. Terylene or DacronCondensation polymerization of terephthalic acidand ethylene glycol, in presence of a weak baseresults in the formation of the most importantpolyester fabric named Terylene. HOOC COOH + OH-CH2-CH2-OH Teraphthalic acid Ethylene Glycol -[-OC-C6H4-CO-O-CH2-CH2-O-]n-
  30. 30. OrlonPolymerization of acrilonitrile (vinylcyanide) inpresence of FeSO4 and H2O2, gives orlon.It is water resistant quick drying, can be woven orknitted, can be blend with wool, used in makingcloths, carpets, blankets etc. Polymerization n CH2=CHCN -[CH2-CH-]- Fe2SO4/H2O2 CN
  31. 31. Composites are reinforced plastics.Composites consists of two components,1. Matrix phase and2. Dispersed phase
  32. 32. 1. Matrix PhaseMatrix phase is the main part of the composite.Metal can give metal matrix composite,Ceramics can give ceramic matrix composite,Polymer can give polymer matrix composite.Matrix should satisfy the following criteria,1. It should be ductile2. The bounding between the matrix and the filler should be strong.3. The fibre and matrix should be chemically compatible with each other.
  33. 33. 2. Dispersed phaseThe reinforcing material should be strong andstiffer than the matrix to increase the strength ofthe matrix.Wood floor, Asbestos, Clay, marble powder, mica, graphite, fibresof glass, cotton, carbon or ceramic may be used as dispersedphase.Metallic oxides like ZnO, PbO or powders of metals like Si, Cu, or Pbare also used.
  34. 34. On the basis of the structures of the reinforcingmaterial, the composites are classified as,1. Fibre reinforced composite: In this type of composite, fibers are embedded in a suitable matrix.2. Particulate composite: These contain particles of a wide range of size dispersed in a matrix.3. Dispersion hardened composite: These contain very fine particles dispersed in a matrix.
  35. 35. Fibre reinforced composite
  36. 36. Glass Reinforced Plastics (GRP)GRP are the most common example of fibre reinforcedplastic. In this plastic acts as the matrix glass fibre as thedispersed phase.These have low density, high tensile strenghth, resistance tothermal and chemical corrosion.GRP finds use in1. Plastic pipes2. Storage tanks3. Speed boats4. Flooring materials5. Automobile parts6. Battery boxes.