b.tech. ii engineering chemistry unit 3 b rubber
TRANSCRIPT
Introduction Rubber is an example of an elastomer type polymer,
where the polymer has the ability to return to its originalshape after being stretched or deformed.
The rubber polymer is coiled when in the resting state.
The elastic properties arise from the its ability to stretchthe chains apart, but when the tension is released thechains snap back to the original position.
The majority of rubber polymer molecules contain at least
some units derived from conjugated diene monomers.
Such conjugated diene monomers have a constructive
backbone of at least four carbon atoms with a double-
single-double bond reactive core (C=C-C=C ).
NATURAL RUBBER Natural rubber is an addition polymer
that is obtained as a milky white fluid
known as latex from a tropical rubber
tree.
Natural rubber is from the monomer
isoprene (2-methyl-1,3-butadiene),
which is a conjugated diene
hydrocarbon .
It comes from latex.
Names of the Trees: Hevea Brasiliensis
and Castilloa elástica.
Elastic, water repellent and electric
resistent.
NATURAL RUBBER
HISTORY
Discovered by the mayans and aztecs.
Banned in the 15th century.
La Condamine rediscovered it in 1735.
It was a success in Europe.
In 1791 it was first commercialized.
NATURAL RUBBERRECYCLING
Different processes to recycle it.
Very flammable.
It creates pollution.
Cause of diseases.
E.g: Rubber floors for parks.
SYNTHETIC RUBBERDESCRIPTION
• Artificial elastomer:Important conjugated dienes used in
synthetic rubbers include isoprene (2-methyl-1,3-
butadiene), 1,3-butadiene.
• Polymerized 1,3-butadiene is mostly referred to simply as
polybutadiene. Polymerized chloroprene was developed
by DuPont and given the trade name Neoprene.
SYNTHETIC RUBBERHISTORY
• Created in 1909 by Fritz Hofmann.
• Similar structure to natural rubber.
• People were very pleased.
• Cheaper than natural rubber.
• 2/3 of today’s rubber is synthetic.
SYNTHETIC RUBBERPROPERTIES
• Solid, flexible, durable.
• It hardens when it’s cooled.
• It can be molded when heated.
• Resistant to heat, light and
chemicals.
• Heat and electrical insulator.
SYNTHETIC RUBBERUSES
• Car tires.
• Flexible rubber toys.
• Paint.
• Shoe soles.
• Rubber gloves.
• Tubes and hoses.
Neoprene:A Synthetic rubberProperties
Synthetic rubber.
It’s produced by polymerization of chloroprene.
It has good chemical stability.
Flexible over a wide temperature range.
It is colourless.
Resistant to sun, climate and ozone deterioration.
Neoprene
HISTORY
It was invented by DuPont scientist (1930).
First name: DuPrene.
It smelled bad and was expensive.
Problems were solved and was a success.
It name was changed to neoprene.
NEOPRENE
RECLYCLING
Waste burying techniques.
Incineration.
Some brands do recycling processes.
Using old neoprene to create shoes, t-shirts…