ALLEN NEET Coaching
ApplyAce your NEET preparation with ALLEN Online Programs
Polymers 2, Polymers 3 are considered the most difficult concepts.
Polymers 1 are considered the most asked concepts.
2 Questions around this concept.
Which of the following statements about low-density polythene is FALSE?
Polymers are the backbone of four major industries, i.e, plastic, fibres, elastomers and paints. Polymers are large molecules having large high molecular masses formed by the chemical combination of a large number of relatively smaller molecules known as monomers. The process by which these polymers are converted into polymers is known as polymerisation.
A polymer always consists of hundreds to thousands of repeating structural units. Thus, all polymers are macromolecules but all macromolecules are not polymers.
Classification based on source
On the basis of source, polymers can be classified into three categories:
Classification of polymers on the basis of monomers
Based on the nature of repeating structural units, polymers are divided into two categories, viz:
Classification of polymers on the basis of synthesis
Polymers can also be classified on the basis of mode of polymerisation into two subgroups.
On the basis of structure
There are three different types based on the structure of the polymers.
Classification based on molecular forces
On the basis of the magnitude of intermolecular forces, polymers have been divided into the following four categories:
1. Elastomers - Polymer chains are held together by weak intermolecular forces, which permits the polymer to stretch.
Eg:- Vulcanised rubber, Buna - S, Buna - N, Neoprene.
2. Fibres - Fibres are thread like material made up of linear chains of polymer having H-bonding between them. They are crystalline in nature.
Eg:- Nylon 66, Terylene, Silk.
3. Thermoplastics - The intermolecular forces are intermediate between elastomers and fibres.They soften on heating and harden in cooling.
Eg:- Polystyrene, Polyvinyls, etc.
4. Thermosetting polymers - They are highly cross - linked, hard, infusible and insoluble polymers.They cannot be reused.
Eg:- Bakellite, Urea, Formaldehyde, Resin, etc
"Stay in the loop. Receive exam news, study resources, and expert advice!"