1)classification based upon source
polymers can be classified based upon source area)Natural polymers:- these are the naturally occurring polymers such as starch cellulose nucleic acid
s and natural rubber.natural rubber is a polymer of isoprene(2-methyl buta 1,3-diene) 
b)Synthetic polymers:- these are man made polymers such as poly vinyl chloride (PVC),Bakelite,nylon,polystyrene etc
based on the method of synthesis polymers can be classified as follows
a)Addition polymers:-these type polymers are formed by the repeated additions of monomeric unit .the monomers involved are unsaturated compounds and are usually the derivatives of ethene
eg:-polypropylene, PVC,polythene,etc belongs in this type
b)Condensation polymers:-these are formed by a series of condensation reaction between two monomers each monomers having two functional group.during condensation simple molecule like H2O,HCl,NH3 etc are eliminated.The reaction is called condensation polymerisation
eg nylone66
based on the inter molecular forces polymers can mainly classified in to 4
a)Elastomers :-the polymers that have elasticity, like rubber are referred to as elastomers.the polymer chain in elastomers are held together by the weakest intermolecular forces.they have ability to be elongated under stress and regain their former shapes when the stress is removed
b)Fibers:-these are thread like polymers which can be woven into fabric.they have high tensile strength and high modulus.this is due to strong inter molecular forces like hydrogen bond.
eg:- cotton,wool,silk,nylon and Dacron etc
c)Thermoplastic:-The inter molecular forces of attraction in the thermoplastics polymers are intermediate between those of elastomers and fibres .As a result thermoplastic polymers when heated became melt and can be molded again in different forms.
eg:- polyethylene polypropylene and polystyrene
d)Thermosetting plastic:- These polymers are prepared from low molecular mass semifluid polymers .thy cannot be reshaped on heating because the polymer chain under go extensive cross linking resulting in the formation of three dimensional network of inter connected polymer chain
eg:- Bakelite,melamine etc
Name : Gowtham Kumar.C
ReplyDeleteYear : 2013 -2014
Branch : B.Tech
Department : IT
College : Arunai College Of Engineering
POLYMERS
DEFINITION:
The process of large number of micro molecule combines to form a macromolecule.
Micro molecule
↓
Monomer
↓
Degree Polymerisation
Example: (CH2=CH2)n → (CH2-CH2-)n
TYPES OF POLYMERS:
There are 3 types,
1. Addition Polymerisation
2. Condensation Polymerisation
3. Co-Polymerisation
`ADDITION POLYMERISATION:
It is the reaction that yields a multiple original monomeric molecule.
Example: Polyethylene produced from ethylene
(CH2=CH2)3 → (CH2-CH2-CH2-CH2-CH2-CH2-)3
CONDENSATION POLYMERISATION:
It is a reaction between simple polar groups containing monomers with the formation of polymer and elimination of small molecules like H2O and so on.
Example: Hexamethylene diamine and adipic condense to form a polymer, Nylon 66.
nH2N-(CH2)6-NH2 + nHOOC-(CH2)4-COOH → -[HN-(CH2)6-NH-C=O-CH2)4-C=O]-
CO-POLYMERISATION :
It is the joint Polymerisation in which two or more different monomers combine to form a polymer.
Example: Butadiamine and styrene copolymerize to form GR-S rubber.
CH2=CH-CH=CH2 + CH2=CH-CH-C6H5 → (CH2-CH=CH-CH2-CH2-CH-C6H5)-
HIGH POLYMER :
Polymer with high degree of polymerization is called high polymer. Its molecular weight range from 10,000 – 2,00,000 lkhs
OLIGO POLYMER :
Polymer with low degree of polymerization is called oligo polymer. Its molecular weight range from 500 – 5000.