DEFINITION
- Natural rubber is the polymer and are also elastomers which are obtained naturally from the latex sap of trees (Hevea brasiliensis, tropical trees and subtropical trees). The natural rubber is made from the latex. The latex is obtained from the bark of certain tropical and subtropical trees. For example, let’s take dandelions if you snap off their stems, you can see the latex from this plant.
- Natural rubber is the polymer of organic compound isoprene with minor impurities of other organic compounds. Natural rubber is made of polymerization of isoprene.it is also known as cis-1,4-poly(isoprene).
Properties of natural rubber:
- It has high tensile strength and high tear strength
- It has great resistance to environmental damage by heat, light and ozone.
- Natural rubber has high resistance to cutting, chopping, and tearing.
Composition of rubber:
|
ELEMENT |
RUBBER FIBER |
|
carbon (C) |
87.51 |
|
Oxygen (O) |
9.23 |
|
Zinc (Zn) |
1.76 |
|
Sulfur (S) |
1.08 |
|
Silicon (Si) |
0.20 |
|
Magnesium (Mg) |
0.14 |
|
Aluminium (Al) |
0.08 |
|
Zinc oxide |
3 |
|
Stearic acid |
1.5 |
Preparation of natural rubber:
Step I
The milky white liquid latex is collected from the trees in a cup. The collected latex is washed, filtered and reacted with acids to solidify the rubber particles.
Step II
These rubber particles are very hard in nature when it is
cold but it is very gluey when it warm condition. Now these rubbers are reacted
with extra chemical ingredients to enhance the properties of the rubber. And also,
to remove the hard nature and strong odour, rubber is passed through the
rollers and it is pressed to make it softer and flexible for the required
process. These steps are repeats depend upon the properties of the rubber.
step III
After step II, the rubber particles are passed through the
roller in the calendering process. It is provided the proper shape to the
rubber.
Step IV
The final product is passed through the designing holes in
an extrusion machine to make the hollow tubes.
Step V
These four steps are not enough for get strong and hard rubber.
For this purpose the rubber is treated with Sulphur and it is heated in the
temperature between 373K to 415K. this step is known as vulcanization. After
this process, the rubber is cross linked with Sulphur and it becomes very hard.
USES OF NATURAL RUBBER:
- Natural rubber is used in the engineering applications such as springs, bearings and drive couplings.
- It is used in the manufacture of rubber bands and adhesives.
- Natural rubber is also used to manufacture of tires for cars, buses, race cars and aircrafts.
- It is used in the manufacture of airbags, rubber gloves, etc.,
