Ans-:
- Polymeric molecules are very big molecules. Their average molecular weights may approach 105 or more. That's why, they are also known as macromolecules, They are in fact, sub-microscopic particles.
- Polymers are semi-crystalline materials. It means they have both amorphous and crystalline regions. In fact, polymers have regions of crystalline, called crystallites, embedded in amorphous regions. Crystallites provide strength and hardness. The amorphous regions provide flexibility to the polymeric material.
- The intermolecular forces in polymers can be Van der Walls' forces, dipole-dipole attractions or hydrogen bonding. These intermolecular forces are in addition to covalent bonds which connect the repeating units in a macromolecule.
- The chemical, electrical, optical, mechanical and thermal properties of polymers depend on (i) size and shape of polymers, and (ii) the presence or absence of characteristic intermolecular forces. These parameters not only determine the properties of the polymers, but also the performance of these materials in a given applications.
- Polymers show time-dependent properties. They show "creep" (their most significant mechanical characteristic ).
- Polymers are combustible materials.
- Polymers have low densities and they show excellent resistance to corrosion.
- Generally, polymers are thermal and electrical insulators.
Polymers contribute to national economy in terms of performance, reliability, cost-effectiveness and high added value.
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polymers