What are Elastomers
An elastomer is a polymer with visco-
elasticity (colloquially "elasticity"), generally
having low Young’s modulus and high
failure strain compared with other materials.
The term, which is derived from elastic
polymer, is often used interchangeably with
the term rubber.
Elastomers are amorphous polymers existing
above their Glass Transition Temperature, so
that considerable segmental motion is
Types of Elastomers
Note: Elastomers are
usually Thermosets (requiring vulcanizaton)
but may also be Thermoplastic.
Thermosetting polymer as a pre-polymer in a soft solid or viscous
state that changes irreversibly into an infusible, insoluble polymer
network by curing. Curing can be induced by the action of heat or
suitable radiation, or both. A cured thermosetting polymer is called a
A thermoplastic, or thermosoftening plastic, is a polymer that
becomes pliable or moldable above a specific temperature, and returns
to a solid state upon cooling. Most thermoplastics have a high molecular
Large elastic elongation (i.e.200%)
Can be stretched and then immediately return to
their original length when the load was released
Elastomers are sometimes called rubber or
The term elastomer is often used
interchangeably with the term rubber
Idealized stress-strain curves for metals,
conventional plastics and elastomer
Solved by Goodyear in the 1800's
Discovered that the polymer could be crosslinked
(cured or vulcanized) by heating with sulphur
•Used in tires for bicycles and early cars.
•Used the Ziegler-Natta catalyst system to improve
•The trans- or cis- nature of the rubber could be
to 90% in either direction.
Butadiene Rubber (BR)
No cis or trans isomers.
Lower mechanical strength because of no of
pendant methyl group but also more flexibility.
Lower cost (all synthetic from cheap monomer)
Improvement of low-temp flexibility.
Compatibility with other polymer materials.
NBR—Nitrile Butadiene Rubber
Copolymerization of butadiene and acrylonitrile
More expensive than SBR or BR
CR—Chloroprene rubber (neoprene)
Thermoplastic Elastomers (EPM
Many of the properties of thermoset
More easily processed
Injection molding, extrusion and other standard
Highly compatible with polyolefins.
EPDM is crosslinked very lightly and may not be
capable of being melted.
Thermoplastic Olefin Elastomers (TP
Block tripolymers (such as SBS) with hard and
Poor compatibility with other rubbers.
s•Many of the desirable properties of
•Low solvent effects
-Excellent for chemical and petroleum
•High thermal stability
-Good for gaskets and seals
Vinylidene fluoride monomer