Write a short note on: Natural rubber.

(N/A) Rubber is a natural polymer and possesses elastic properties.
It is also termed as an elastomeric polymer. In elastomeric polymers,the polymer chains are held together by weak intermolecular forces. These weak binding forces permit the polymer to be stretched.
$A$ few 'crosslinks' are introduced in between the chains,which help the polymer to retract to its original position after the force is released.
Rubber has a variety of uses. It is manufactured from rubber latex,which is a colloidal dispersion of rubber in water.
This latex is obtained from the rubber tree,which is found in India,Sri Lanka,Indonesia,Malaysia,and South America.
Natural rubber may be considered as a linear polymer of isoprene ($2$-methyl-$1,3$-butadiene) and is also called $cis$-$1,4$-polyisoprene.
The $cis$-polyisoprene molecule consists of various chains held together by weak van der Waals interactions and has a coiled structure.
Thus,it can be stretched like a spring and exhibits elastic properties.
The chemical structure is as follows:
Isoprene: $CH_2=C(CH_3)-CH=CH_2$
Natural rubber: $-(CH_2-C(CH_3)=CH-CH_2)_n-$