Question

What are the differences between Buna-N and Buna-S?

Answer 1

Hint- In order to solve this problem we will compare Buna-N and Buna-S on various factors like their chemical name, common name, process of formation, uses and then we will make the list of the differences between these two compounds.

Complete answer:
Buna-N
- Buna-N monomers are 1,3-butadiene and acrylonitrile.
- It is formed by polymerization of 1,3-butadiene and acrylonitrile in the presence of sodium.
- It is also called Nitrile-Butadiene-Rubber. It is a copolymer of butadiene and acrylonitrile.
- Cyanide ions in acryl groups enhance the oil and solvent resistance hence the oil resistance is determined by the amount of acrylonitrile.
- It is used in seals, belts, oil seals etc and also used for making synthetic leather and footwear.
- It is a commercial name for NBR.

Buna-S
- BUNA-S monomers are 1.3-butadiene and styrene.
- It is formed by the polymerization of 1,3-butadiene and styrene in the ratio 3:1 in the presence of sodium.
- It is also called Styrene-Butadiene Rubber.
- This has significantly less resistance to friction than natural rubber.
- It is used for making automobile tyres and rubber soles.
- Its commercial name is SBR.

Note- Both BUNA-N and BUNA-S are polymers. Buna-N is used for making oil seals, manufacturing of tank linings, protective gloves etc. Buna-S is used for making automobile tyres, rubber soles, belts, hoses etc. in order to compare two these are the basic factors. Students must remember the monomer of each of the given polymers in order to solve such questions.