classification of polymer on different basis
TRANSCRIPT
Classification Of Polymers
Presented byDevansh GuptaM.Sc Polymer
ScienceSemester 1
Contents Some Basic Definitions Classification Of Polymers
1. By Origin2. By Monomer3. By Thermal Response4. By Mode Of Formation5. By Structure6. By Application & Physical
Properties7. By Tacticity
Reference
Definition
The word ‘polymer’ comes from the Greek words poly (meaning ‘many’) and meros (meaning
‘parts’).Example: POLYETHYLENE =
(ETHYLENE+ ETHYLENE+......)n Where n = 4,000
Polymers are very large molecules made when hundreds of monomers join together to form long
chains.
MonomerThe small individual repeating
units/molecules are known as monomers(means single part).
Imagine that a monomer can be represented by the letter A. Then a polymer made of that monomer would have the structure:
-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-
Polymerization• The process by which the monomer
molecules are linked to form a big polymer molecule is called ‘polymerization’.
• Polymerization is a process of bonding monomer, or “single units” together through a variety of reaction mechanisms to form longer chains named Polymer
• As important as polymers are, they exist with monomers, which are small, single molecules such as hydrocarbons and amino acids.
Classification Of Polymers
1. By Origin2. By Monomer3. By Thermal Response4. By Mode Of Formation5. By Structure6. By Application & Physical Properties7. By Tacticity
By OriginNatural PolymersPolymers which are isolated from
natural materials are called as natural polymers.
E.g. Silk, Wool, Natural rubber, Cellulose, Starch, Proteins etc.
Natural RubberHevea Brasiilensis
Semisynthetic PolymersThe polymers obtained by simple
chemical treatment of natural polymers to improve
their physical properties like lustrous nature, tensile strength are called semisynthetic polymers
E.g. Cellulose acetate, Cellulose nitrate
Synthetic Polymers
Polymers synthesized in laboratory from low molecular weight compounds, are called as, synthetic polymers.
E.g. Nylon, Terylene, Polyethylene, Polystyrene, Synthetic rubber, Nylon, PVC, Bakelite, Teflon etc.
By MonomerHomo PolymersA polymer consist of identical monomers
is called homo polymer. E.g. Polyethylene, PVC, Polypropylene, Nylon 6
Co PolymersA polymer consist of monomers of different
chemical structure are called copolymers. E.g. Nylon 6,6
By Thermal ResponseThermoplastic Polymers They are easily moulded in desired shapes by
heating and subsequent cooling at room temperature.
They are soft in hot and hard on coding. They my be linear or branched chain
polymers. E.g. PE, PVC, PS, PP
Thermosetting PolymersThis polymer is hard and infusible on heating.These are not soft on heating under pressure and
they are not remolded.These are cross linked polymers and are not
reused. E.g. Bakelite
By Mode Of FormationAddition PolymersThe polymers formed by the addition of
monomers repeatedly without removal of by products are called addition polymers.
These polymers contains all the atoms of monomers hence their molecular weight are integral multiple of monomer unit.
E.g. Teflon, Polyethylene, Polypropylene, PVC.
Condensation PolymersThey are formed by the combination of
two monomers by removal of small molecules like H2O, Alcohol or NH3. Their molecular mass is not the integral multiple of monomer units.
They have ester and amide linkage in their molecules.
E.g. Polyamides(Nylons), Polyesters(PET)
By StructureLinear PolymersIn these polymers monomers are linked
with each other and form a long straight chain.
These chains has no any side chains.Their molecules are closely packed and
have high density, tensile strength, and melting point.
E.g. HDPE, Nylons
Branched PolymersThey have a straight long chain with
different side chains.Their molecules are irregularly packed
hence they have low density, Tensile strength and melting point.
E.g. LDPE, LLDPE
Cross-linked PolymerIn these monomeric units are linked
together to constitute a 3D network.The links involved are called cross links.They are hard, rigid .and brittle due to
their network structure.E.g. Bakelite, Melamine, Formaldehyde resins, Vulcanized rubber
By Applications & Physical Properties
FibersIf polymer is drawn into long filament like
materiel whose length is at least 100 times it’s diameter, are said to be converted into fiber.
They have high tensile strength because of high intermolecular attractive force like Hydrogen bonding.
Highly crystalline. E.g. Nylon, Terylene.
PlasticsPolymer is shaped into hard and tough
utility articles by application of heat and pressure, is known as plastics.
Here the intermolecular force between polymeric chains are intermediate between elastomers and fibers.
They are partially crystalline. E.g. Polystyrene, PVC, PMMA
ElastomersThey are solids with rubber like elastic
properties.Here the polymeric chains are held
together by the weakest intermolecular forces so they are highly amorphous in nature.
These weak binding forces permit them to be stretched.
E.g. Natural rubber, BUNA-S, BUNA-N, Vulcanised rubber
ResinsLow molecular weight.Polymers which are used as adhesives,
sealants etc., in a liquid form are described as liquid resins.
E.g. Epoxy adhesives and polysulphides sealants.
By TacticityTacticity simply means
deposition of side groups in space.
The head to tail configuration in which the functional groups are all deposited on the same side of the chain, is called isotactic polymers.
If the deposition of side groups is in alternating fashion, it is called synditactic polymers.
If the deposition of side groups are at random around the main, it is called atactic polymers.
Other Parameters Of Classification
By Crystallinity1. Crystalline – Monomers arranged in ordered
way.2. Amorphous – Monomers arranged in random
way.
By Backbone Atom1. Organic – Polymer Backbone is made-up of
carbon atom.2. Inorganic – Polymer Backbone is made-up of
other atoms
ReferencesPolymer Science - Gowariker V. R., New
age International PublishersTextbook of Polymer Science - Billmeyer
F. W, Wiley India PublishersAdvanced Polymer Chemistry – Manas
Chanda Marcel Dekker INC.