B.tech. ii engineering chemistry unit 3 B rubber

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 ).

Types of Rubber

Types of

Rubber

Natural Rubber

Synthetic Rubber

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.

NATURAL RUBBERUSES

Tires.

Wheel rims.

Hoses.

Conveyor belt.

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.

Obtained mainly from petroleum.

• Elastic material.

• Good qualities and cheap.

• It is recyclable.

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…

NEOPRENE

USES

Laptop sleeves

Wetsuits

Small boats

Boots

2

References1.A text book of engineering Chemistry by shashi Chawla

2.https://www.Google.com

3. Engineering Chemistry by Jain and Jain