Question

1. What kinds of bonds would be expected in polymeric materials?

2. State the difference between:
a) Linear and branched polymers.
b) Thermosetting and thermoplastic polymers.

Answer 1

1.Ans

The atoms in the polymer molecules are held together by mainly covalent bonds and polymer chains are held together by secondary bonds and the combination form the polymeric material. A polymer mainly contains a chain of carbon atoms. There are four electrons in the outer shell of carbon and these valence electrons are joined by the covalent bond to another carbon atom of the polymeric chain.

2.Ans

A. Difference between Linear and branched polymers

• A branched polymer has a branched structure while in linear polymer monomer units forms a straight line i.e. branching is present in branched polymers and absent in linear polymers.
• Branched polymers have polymer chains as side groups while linear polymers don't have polymer chains as the side group but they are connected with the main chain.
• In branched polymers, polymer chains are in such a way that it has a very complex structure.Linear polymers have a simple structure rather than complex structure.
• Usually, the melting and boiling point of branched polymers is lower than that of linear polymers while the melting and boiling point of linear polymers is high.

B. The difference between thermosetting and thermoplastic polymers

1. Thermoplastics polymers melt on increasing temperature and get soften whereas thermosetting polymers become hard on increasing temperature.
2. Thermoplastics polymers are soluble in organic solvents while thermosetting polymers insoluble in organic solvents.
3. Thermoplastics polymers are the less brittle while thermosetting polymers are more brittle as compared to the former.
4. Thermoplastics can be remoulded while the thermosetting plastics can’t be reshaped because they don't soften on heating.
5. Thermoplastic polymers usually have linear structures while thermosetting polymers have cross-linked structures.
6. Thermoplastics are formed by addition polymerisation while thermosetting polymers are formed by condensation polymerization.
7. Thermoplastic polymers have low molecular weight whereas the later one has high molecular weight.
8. In the thermoplastic polymer, monomers used are generally bifunctional while in case of thermosetting polymers monomers can be bi, tri, tetra or polyfunctional.