Polymer
[3 Marks]
Polymer (origion Greek) poly means many, mers means part
Defination: Very large molecules having high molecular mass (103-107 u)
Macromolecule: other name for polymer
Polymerization: the process of formation of polymer
Classification of polymer:
1. Based on sources:
a. Natural: from plants and animal sources for example starch cellulose rubber etc.
b. Semi synthetic: polymer with modification of natural polymer for example rayon.
c. Synthetic prepared in laboratory for example nylon, ethylene etc.
2. Based on structure of polymer:
a. Linear: long and straight change for example PVC
b. Branched: linear polymer with branches for example low density plastic
c. Cross linked or network: contains strong covalent bond between various linear polymer for example Bakelite, melamine .
3. Based on mode of polymerization:
a. Addition polymerization: repeated unit of monomers having unsaturation in its structure
i. Homo-polymer: when monomer is of same kind for e.g. polyether, PVC
ii. Copolymer polymer having two different monomers for e.g. Buna-S, Buna- N
b. Condensation polymerization: repeated condensation reaction between mostly two different bi-functional monomer unit with the elimination of water alcohol etc. for e.g. nylon 66, Dacron
4. Based on molecular forces
a. Elastomers: rubber like solid with stretchable property up to some extant for e.g. Buna-S, Buna N.
The force between chains is weak Vanderwall force.
b. Fiber: thread like solid with high tensile strength
Force between chain is hydrogen bonding for e.g. polyester, nylon 6, 6
c. Thermo plastic: linear or slightly branched long chain molecule, soften on heating. For example polyethylene PVC. Etc.
d. Thermosetting: cross linked molecule once setup can’t not be soften on heating. for example Bakelite, melamine
Decreasing order of force of attraction between the chains
Thermosetting > Fiber> Thermoplastic> Elastomers
Difference between thermoplastic and thermosetting
Type of polymerization reaction:
Addition polymerization or chain growth:
· Due to increase in the length of chain
· Due to addition of similar monomer it is addition polymerization e.g. polythene
Steps of addition polymerization with free radical mechanism:
Chain initiation :by molecules like Benzoyl peroxide(C6H5OCOOCOC6H5)
Chain propagation : through free radical
Chain terminalisation :combination of free radicals.
Q .which catalyst is used in HDP like polythene?
A. Zeigler-Natta catalyst.
Q. what is Zeigler-Natta catalyst?
A. Triethylaluminium (C2H5)3Al and titanium tetrachloride(TiCl4)
Condensation polymerization or step growth:
Since each step produces a functionalized species and is independent of each other,this is called step groth.
As,monomers with different functional groups are condensed,so, it is Condensation polymerization.
e.g. Condensation between Hexamethylene-di-amine[ NH2-(CH2)6-NH2] and Adipic acid[HOOC-(CH2)4-COOH in Nylon-6,6.
Q.why nylon is named as such?
A.It is Acroname of New-York and London.
Q .why is it called 6,6?
A. As the monomers contain six carbon each i.e. Hexamethylene- di - amine[ NH2-(CH2)6-NH2] and Adipic acid [HOOC-(CH2)4-COOH.
Q. what is the monomer of nylon-6?
A. Caprolactum [NH2-(CH2)5-COOH].
Q. Which properties of polyester make it more usable fibre ?
A. Crease resistant, Dip dry, Blending with other natural fibre like cotton, wool etc.
Q. what are different kinds of blended polyester?
A. Tere-Cot (Terelene with Cotton)
Tere-Wool (Terelene with Wool)
Tere-Silk (Terelene with silk)
Q.A Tere-Cot shirt is marked as 60-40.What does it mean?
A. It contains 60% terelene and 40% cotton.
Q. What is the source of natural rubber?
A. Milky latex from rubber tree.
Q. Which countries are the greater producer of rubber ?
A. Sri –Lanka, Malaysia, Indonesia, South America.
Q. What is the monomer of natural rubber?
A. Isoprene (2-Methylbut-1,3-diene).
Q. What is a vulcanized rubber?
A. When natural rubber is heated with sulphur, it forms cross-linkage of sulphur between linear polymers. Such rubber is called vulcanized rubber.
Q. How is vulcanized rubber than natural rubber?
A. vulcanized rubber Natural rubber
1. Non sticky 1.Sticky
2. Linkage of sulphur 2.Linear chain
3. Less absorbent of water 3. Absorbs water
4. Easily oxidized 4. Less oxidized
5. Working temp. -40 to 120 0C 5. Working temp. 40 to 120 0C
6. Tough and hard 6. Soft
Q. What is Neoprene rubber?
A.2-Chlorobut -1,3-diene
Q. Why is Neoprene rubber non –inflammable ?
A. Due to presence of chloro group .
Q. What is Bio-degradable polymer?
A. The polymers which can be degraded by microbes. e.g. PHBV and Nylon-2 ,Nylon-6.
Q. Give full form of PVC, PTFE,PHBV?
A. PVC: Poly Vinyl Chloride
PTFE : Polytetrafluoroethene
PHBV : poly-β-hydroxybutyrate-co-β-hydroxy valerate.
Name of polymer Monomer structure Uses
Addition polymer
Polythene Ethene CH2=CH2 Carry bags,toys,buckets
PTFE(Teflon) Tetraflouroetene CF2=CF2 Non -stick cookware,Oilseals,gasket
Polyacrylonitrile Acronitrile CH2=CHCN Substitute for wool(mink)
Polypropene Propene CH2=CHCH3 ropes,pipes
Polystyrene Styrene CH2=CHC6H5 Insulator,Wrapping material
PVC Vinyl Chloride CH2=CHCl Raincoats,flooring,water pipes
(Thermocol)
Condensation polymer
Nylon 6,6 Adpic Acid COOH-(CH2)4COOH Parachute Rope, Socks, Stockings
Hexamethylene- di – amine [ NH2-(CH2)6-NH2]
Nylon 6 Caprolactum [NH2-(CH2)5-COOH] Parachute Rope, Socks, Stockings
Dacron Ethylerne Glycol OH-(CH2)2OH
Terephthalic Acid COOH-C6H4-COOH Blended Fibers, Socks, Stockings
Bakalite Formaldehyde HCHO Electric switches, Handel of pressure cooker
Phenol C6H5OH
Melamine Formaldehyde HCHO Unbreakable Crockery
Melamine C3N6H6