Question

How is BUNA – S prepared? Write any 2 uses and properties of it.

Answer 1

Polymer

• Polymer is a large molecule composed of repeating structural units connected by covalent bonds.
• The units from which polymers are synthesized are called monomers.
• Polymers make up many of the materials in living organisms and are the basis of many minerals and man-made materials.
• Example: Plastics

Copolymer

• A copolymer is a polymer made from more than one kind of monomer.
• A copolymer is a polymer formed when two or more different types of monomers are linked in the same polymer chain.
• Example: Polyethylene-vinyl acetate (PEVA),

Copolymerization:

• In Copolymerization, two or more different monomers or monomeric units are allowed to polymerize together to form the product.
• Example: Buna -S (copolymerization of butadiene and styrene)

Buna-S

• Buna-S is a polymer.
• Its name derives Bu stands for butadiene and Na stands for sodium and S stands for Styrene.
• It is formed by the copolymerization of butadiene and styrene.

Preparation

• It is prepared by copolymerization of 1,3 butadiene $(75\%)$and styrene$(25\%)$ with sodium.
• Reaction:

• Styrene reacts with Butadiene and double bond breaks to add butadiene group leading to the formation of Buna- S.

Uses

• It is used for making tyres, and conveyor belts.
• They are also useful in making shoe soles, footwear, electrical insulations, etc.

Properties

• They have a high load-bearing capacity.
• Buna-S is a polymer, that has high resistance to abrasion.