1. Polymers
You may think of polymers as being a relatively modern invention however naturally occurring polymers have been used for thousands of years – wood, rubber, cotton, wool, leather, silk,.. etc • Artificial polymers are, indeed, relatively recent and mostly date from after WWII in many cases, the artificial material is both better and cheaper than the natural alternative

3. A polymer is a large molecule of high molecular mass made by linking together repeating units of small molecules called monomers

5. Polymerization: process of joining small monomers to form a polymer.
Degree of polymerization(n): the number of monomeric units which combine to form a polymer.

7. Classification on basis of availability or occurrence
Natural polymers
e.g. starch, cellulose, proteins, natural rubber
Semi-Synthetic polymers
e.g. Vulcanized rubber
Synthetic polymers
e.g. Polyethene, nylon, Teflon

8. Classification on the basis of:

9. Classification on basis of monomer units
homopolymers
One type of monomer units e.g. polyethene
copolymers
Two or more than two types of monomers e.g. styrene-butadiene rubber

10. Buna S/ Styrene Butadiene rubber/ SBR/GR-S Rubber
Uses: For making automobile tyres, rubber soles, belts etc.
Buna N/ Nitrile Butadiene rubber/ NBR/ GR-A Rubber
Uses: Aeronautical applications, footwear, sponges, floor mats etc.

12. Classification on basis of Method of Synthesis/Polymerization
Addition or chain growth Polymerization
Condensation or step growth Polymerization
Addition or chain growth Polymerization: done by addition of monomer units having multiple bonds and without the elimination of any molecule. e.g. Polyethene , polypropylene

15. 2) Condensation or step growth polymerization Monomers containing some active functional groups react together with the elimination of simple molecules like NH3, H2O, CO2 etc. nH2N(CH2)6NH2 + nHOOC(CH2)4COOH  (-HN(CH2)6NHCO(CH2)4CO-)n + nH2O hexamethylene adipic acid nylon-66 diamine

16. Polyamide
Nylon66:
Uses: for making bristles for brushes, blended with wools for making socks and sweaters etc.
Nylon 6
Uses: tyre cords, fabrics and ropes.

17. .
Nylon 6,10

18. Polyesters Terylene/Dacron:
Uses: for making cloths by mixing with cotton, magnetic recording tapes.
Glyptal:
Uses: in manufacturing paints and lacquers, building materials such as asbestos, cement etc.

19. Uses of PET Poly(ethyleneterephthalate)
polyester fabrics are used in apparel and home furnishings such as bed sheets, beds, table sheets, curtains and drape
used in tyre reinforcements, ropes, fabrics for conveyor belts, safety belts, coated fabrics and plastic reinforcements with high energy absorption
Polyester fibers are also used to stuff pillows, comforters and cushion padding

20. Classification on basis of thermal properties
Can’t be reshaped.
Thermosetting:
Undergo chemical changes and cross linking on heating and become permanently hard, rigid on cooling. e.g. Phenol-formaldehyde, Bakellite, Urea formaldehyde resin
Can be reshaped
Thermoplastic:
Soften on heating and can be converted into any shape. E.g. PE,PTFE, PMMA

23. Classification on basis of intermolecular forces or end use
Elastomers: undergo long elongation when pulled and return to original position when released. Buna-S, natural rubber
Fibers: long, thin, thread like polymers, whose length is at least 100 times their diameter. They do not undergo stretching and deformation like elastomers., linked by H-bonding. E.g jute, silk, Nylon 66
Resins: low mol. Wt. polymers, used as adhesives. Liquid or powders e.g. Phenol-formaldehyde
Plastics: can be molded into desired shape by heat or pressure e.g. PE, PVC

24. Classification on basis of elemental composition
Organic polymer: Having carbon atoms in their polymer backbone. PE. PVC, PAN
Inorganic polymer: Do not have carbon atoms in their polymer backbone. Boron nitride, silicon polymer.

25. Inorganic polymer
[ B=N ]n
Boron nitride
Silicon Polymer

26. Classification on basis of configuration/stereochemistry/Tacticity

27. Tacticity: It is relative stereochemistry of adjacent chiral centres within a macromolecule (polymer).
If the monomer unit has a chiral center than different stereochemistry is obtained. Polymerization of such a monomer yield different stereoisomers.
e.g. polymerization of propene.
three types of stereochemistry is possible
Isotactic: If similar groups are all on the same side of the chiral centre i.e. if stereochemistry at all the chiral centre is same within a macromolecules.

28. Syndiotactic: If stereochemistry at alaternating chiral cnetre is same within a macromolecules.
Atactic: If the stereochemistry at chiral centre is random. within a macromolecules.

29. Classification of polymer on basis of electrical properties
Insulating polymer
Polymer which do not conduct electricity e.g. polyethylene, PVC, PAN etc
Conducting polymer
Polymer which conduct electricity e.g. polyacetylene, polypphenylene, polyaniline

30. Conducting polymers Before 1960 organic polymers used as insulators.
In 1960 Chemist Shirakawa ,Plastic research lab. BASF, Germany, accidentally added a catalyst 1000 times more than the required during polymerization of acetylene ,which result in conducting polyacetylene.
Organic polymers having electrical conductance of the order of conductors are called conducting polymers.
Classification:
Extrinsically conducting polymers (conductivity due to mixing conducting fillers like metal fibers, metaloxide, carbon black with insulating materials)
Also called as Conductive element filled polymers.
Insulation material formed the continuous phase and the added filler form the conducting networks.
Minimum concentration of conducting filler has to be added so that polymers start conducting.
Conductance is not due to matrix is due to fillers.

31. Intrinsically conducting polymers (for example, poly (p- phenylene), polyacetylene, polyaniline)
-Conductivity is due to organic polymers themselves.
They conduct electricity when doped with Oxidizing ,reducing agents or protonic acids

43. Copolymerization
It is process of formation of polymer from different types of monomer units.
E.g. Buna N, Buna S

45. Strength: Tensile strength increase with molecular mass up to a certain point and then become constant. Commercially a polymer should have high tensile strength.

46. Melt viscosity shows gradual increase with increase in molecular mass.

47. Crystallinity
Crystallinity: Degree of crystallinity of polymer depends on its structure. Linear polymer will have high crystallinity. Eg HDPE is more crystalline than LDPE. LDPE is more crystalline than Polystyrene. Isotactic, syndiotactic highly crystalline. Nylon 66 high degree of crystallinity. Polymers having polar groups can formed hydrogen bond with neigbouring chain.

48. Crystallinity Linear structure Polar groups Stereo regularity
Avoid bulky group

49. Elasticity
Induce cross linkage
Non-polar groups
Avoid bulky group
Elasticity: It is mainly because of uncoiling and recoiling of molecular chains on application of force.
Non-elastic Nature of Fibers: The chain mobility is reduced by very close packing of the polymer chain backbone without cross linking. Polar groups and aromatic rings in the backbone chain impart high strength to the polymer fiber.

50. Chemical Resistivity: It depends on the structure of polymer and nature of attacking reagent. When the chemicals attack on polymer, it first softens, swells and loses its strength, and then dissolves. It also depends on several factors such as polar and non polar groups, molar mass, degree of crystallinity, cross linking etc.

51. Glass transition temperature (Tg) is the temperature below which a polymer is hard, brittle and above which it is soft and flexible.

54. Glass transition temperature (Tg)
It is the temperature below which a polymer is hard, brittle and above which it is soft and flexible. Denoted by Tg. Hard brittle state is known as glassy state and soft flexible state is called the rubbery state.
Factors affecting Tg:
1. Flexibility: Presence of rigid groups (aromatic, bulky) in the carbon chain backbone hinders freedom of rotation. This restriction in the chain mobility increases the Tg value.
2. Effect of side group: Poly(-methyl styrene) has higher Tg (170 C) while polystyrene has lower (100 C) due to presence of extra methyl group which hinders free rotation.
3. Intermolecular forces: Presence of large number of polar groups in the molecular chain lead to strong intermolecular cohesive forces which restricts the segmental/ molecular mobility. This leads to increase in Tg value.

55. 4. Branching and Cross linking: A small amount of branching will reduce the value of Tg, because the free volume increases with branching and thus decreases the Tg. High density of branching brings the chain closer and thus reduces the mobility, thereby increasing Tg.
5. Presence of Plasticizers: Addition of plasticizers reduces the Tg value. Eg diisooctyl phthalate which is added to PVC reduces its Tg from 80 c to below room temperature.
6. Stereo-regularity: Tg increases with stereo-regularity. Thus Tg of isotactic polymer is greater than syndiotactic which in turn has greater tg than atactic polymer.
7. Molecular Weight: Tg of all polymers increases with molecular weight up to 20, 000 and beyong this the effect is negligible.

56. Significance of Tg Tg value is a measure of flexibility
Its value gives and idea of thermal expansion, heat capacity, refractive index, electrical and mechanical properties of a polymer.
Its value decides whether a polymer at room temperature will behave like rubber or plastic.
It helps in choosing the right temperature for fabrication.

57. Plastic deformation
Thermopalstic on heating becomes Soft on further heating beyond melting point it melt & flow Such properties called plastic deformation. Thermoplastic exhibit plastic deformation (linear chains , weak vander waals force).While thermosetting plastic doesn’t because of cross linking.
Significance of Plastic deformation: used in molding operation.
Thermosetting polymers do not exhibits plastic deformation, because they undergoes cross linking during molding to form 3-D structural material.
All monomer units are held together by strong covalent bond throughout the structure.
On heating, degradation of polymer occurs instead of plastic deformation due to breaking of covalent bond

58. Chemical structure of basic polymers

60. Natural Rubber
Synthetic Rubber/Neoprene
Uses: For making stoppers, shoe heals, containers for storing petrol, oil and other solvents.

61. Polystyrene/Styron
Monomer: Styrene
Uses: for making hot drink cups, combs, radios and television bodies, tiles to be used in covering ceilings and floors.

62. Polyacrylonitrile (PAN)/ orlon
Uses: for making blankets, sweaters, synthetic carpets etc.

63. Polytetrafluoroethylene (PTFE)/ Teflon
F2C = CF2 → [ F2C-CF2 ] n
Tetrafluoroethylene Teflon

64. Properties and uses of polymer
Good fiber-forming material and is converted into commercial fibres.
Have high stretch, high crease and wrinkle resistance.
Highly resistant to mineral and organic acid, but is less resistant to alkalies.
Used for making synthetic fibres like terylene, dacron etc.
For blending with wool to provise better crease and wrinkle resistance.
A glass reinforcing material in safety helmets, aircraft battery boxes, etc.

70. LDPE/low density polyethylene: It is formed from ethylene monomer under high temperature and pressure conditions. It is highly branched polymer. Due to branching the polyethylene chains do not packed closely.. Therefore, it has low density. It is used for making thin plastic film bags, insulating wires and cables etc.
HDPE/High density polyethylene: It is formed from ethylene monomer in the presence of triethylaluminium ((C2H5)3Al) and Titanium tetrachloride (TiCl4) catalyst (Ziegler Natta Catalyst) at low temperature and pressure. It consists of linear chains. Therefore, the polyethylene chains are closely packed. Hence it has high density. It is used for making containers, pipes etc.