4. Elastomers : -
An Elastomer is a polymer with viscoelasticity (i.e.,
both viscosity and elasticity) and very weak intermolecular
forces, and generally low Young's modulus and high failure
strain compared with other materials
Now we have some key point to identify
elastomers
4
5. 1. IUPAC defines the term "elastomer" by
"Polymer that displays rubber-like elasticity.
2. Elastomers are amorphous polymers
3. Elastomers are usually thermosets but may also
be thermoplastic
4. the elastomer will return to its original configuration
when the stress is removed
5
6. Now we see in this example clearly : -
(A) is an unstressed polymer.
(B) is the same polymer under
stress.
When the stress is removed, it will
return to the A configuration. (The
dots represent cross-links)
6
7. There are some Example of Elastomers In our daily
life : -
1. Natural polyisoprene(cis or Trans)
Fig :- Gutta Percha Fig :- Cameroon tree Fig :- Rubber latex
7
8. 2. Synthetic rubber i.e., Polybutadiene rubber
* It is a polymer formed from the polymerization of the monomer 1,3-
butadiene.
* Polybutadiene has a high resistance to wear and is used especially in
the manufacture of tires and
* which consumes about 70% of the production
8
9. 3. Butyl rubber, sometimes just called "butyl", is a synthetic
rubber
* A copolymer of isobutylene with isoprene.
* The abbreviation IIR stands for isobutylene isoprene
rubber.
* Polyisobutylene, also known as "PIB" or polyisobutene
Fig : - Hand gloves made from Polyisobutylene
9
10. 3. Ethylene-vinyl acetate (EVA)
also known as poly (ethylene-vinyl acetate) (PEVA)
*It is the copolymer of ethylene and vinyl acetate.
* The weight percent vinyl acetate usually varies from 10 to 40%,
with the remainder being ethylene.
Fig : - EVA foam sheetsFig : - ShoesFig : - Pool noodles
10
11. 4. Silicone rubber is an elastomer (rubber-like
material)
* composed of silicone—itself a polymer—
containing silicon together with carbon, hydrogen,
and oxygen.
* Silicone rubbers are widely used in industry,
* resistant to extreme environments and temperatures
from -67 °F to 572 °F (-55 °C to 300 °C)
Fig : - Liquid Silicone Rubber
Fig : - A silicone
rubber pastry
brush.
11
12. How elastomers made from Natural And Synthetic
resources
1. Rubber tapping : -
In This Process The milky white liquid latex is collected from the
rubber trees in a cup by making a slight V-cut on the tree bark.
Fig : - Figure shoes Process Of Tapping
12
13. 2. Mastication – The rubber obtained from the tapping
process is still not ready to be used. When it is cold it is very
brittle in nature and when warmed up it becomes very
gluey. To remove the brittle nature and strong odor of the
rubber
Fig : -
In this Figure A Man drawn the Rubber
Into Mastication Machine Which Obtained
From Tapping Process
13
14. 3. Vulcanization : –
“Vulcanization is a Process Of Heating of Rubber
With Sulphur At very High Temperature “
The process was discovered in 1839 by the U.S.
inventor Charles Goodyear
Even after performing all these steps rubber is not
much stronger and harder to be used in various items
like car tires and machinery. To enhance all these
properties, sulphur is added to
14
15. the rubber and it is heated at a temperature ranging 373
k to 415 k. This process is known as
vulcanization. Sulphur acts as a cross-linking agent and
after vulcanization, rubber gets cross-linked and becomes
hard.
15
16. Properties of Elastomers :-
1.Glass Transition Temperature : -
The glass–liquid transition, or glass transition, is the
gradual and reversible transition
in amorphous materials (or in amorphous regions
within semi crystalline materials), from a hard and
relatively brittle "glassy" state into a viscous or
rubbery state as the temperature is increased
* The glass-transition temperature Tg of a material
characterizes the range of temperatures over which this
glass transition occurs.
16
17. * It is always lower than the melting temperature, Tm, of the
crystalline state of the material
Fig : - This Graph Shows Measurement of Tg (the
temperature at the point A) by differential scanning
calorimetry
An Example Of Glass transition in our Daily Life
Fig : - In this We clearly See The transition In ironing, a fabric is heated through the glass-
rubber transition.
17
18. There are Various Polymers With Glass Transition
Temperature (Tg) : -
Material Tg (°C) Tg (°F)
Commercial
name
Tire rubber −70 −94
Polyvinylidene
fluoride (PVDF)
−35 −31
Polyvinyl fluoride (PVF) −20 −4
Polysulfone 185 365
Polystyrene (PS) 95 203
Polypropylene (PP isotactic) 0 32
Polypropylene (PP atactic) −20 −4
Polynorbornene 215 419
Polylactic acid (PLA) 60–65 140–149
18
Continue
20. 2. It May Possibly Used in Temperature Range Approximately -40
to 100 Degree Centigrade. It Exhibits Elongation Up to 450 to 500 %
.
3. It possesses Good Physical properties , Excellent abrasion
resistance but sensitive to
oil , waste water and ozone ; show good but not outstanding
Electrical properties.
4. SBR is superior to natural rubber because of its easy processing
and good quality end
Products
5. Because of its irregular structure , SBR does not crystallize.
20
22. Application of rubber in our daily life
1. Industrial Rubber
Since World War II, rubber has found its way into an
innumerable amount of industries, for an even greater
amount of applications
Feet, Pads, Bumpers Heavy Duty Rubber Rubber Shock AbsorbersFoam Sponge Rubber
22
23. 2. Smart Products
Rubber-Cal stocks an entire inventory of specialty rubber items.
These range from flexible ducting hoses to rubber parts for
snowplows, street sweepers, and woodworking sanders
Flexible Ducting Street Sweeper Parts Rubber Snowplow Cutting Edges
23
25. 4. Percentage of elastomers used in Industrial
Coatings Resins
Polyurethanes are versatile
polymers with a broad range of
applications across many industries
Polyurethane coatings are applied
to products to improve their
appearance and provide protection
from environmental conditions,
such as sunlight UV, abrasion, rain
Fig : - Graph Show % of elastomer
used in industrial coating resins
25
