Classification of polymer

Classification of polymer

Thousands of different polymers have been synthesized and more will be produced in the future. Conveniently, all polymers can be assigned to one of two groups based upon their processing characteristics or the type of polymerization mechanism. A more specific classification can be made on the basis of polymer structure. Such groupings are useful because they facilitate the discussion of properties

Classification based on broad sense.

(a)    Biological polymer.  e.g – D.N.A, R.N.A, Protein.

(b)    Non- biological / Industrial polymer:  e.g. fibre, plastic, rubber, adhesive materials, coating materials.

Classification of Industrial Polymers:

1. On the basis of origin / source

(i) Natural: Those isolated from natural material

                              e.g cotton, silk, wool, rubber, Cellulose rayon.

(ii) Synthetic: Polymer synthesized from low molecular weight compound.          

                                  e.g. Polyethylene, Poly vinyl chloride

2. On the basis of chemical nature of the polymer,

(i) Inorganic: Polymer generally contains no carbon atom in their chain backbone.               

                                  e.g.  Glass, Silicon, Rubber etc

(ii) Organic: A polymer whose backbone is essentially made of carbon atom.   

                                   e. g.  poly ethylene, PVC, Nylon.

3 On the basis of behavior towards heat :

All polymers can be divided into two major groups based on their thermal processing behavior. 

(i) Thermo plastic: Polymer which soften on heating and stiffen on cooling are termed Thermoplastic. 

Those polymers that can be heat-softened in order to process into a desired form are called thermoplastics. Waste thermoplastics can be recovered and refabricated by application of heat and pressure. Polystyrene is an important example of a commercial thermoplastic,    e.g.- Polyester, nylon.

(ii) Thermo setting: Polymers which become infusible and insoluble mass on heating are called Thermo setting.

In comparison, thermosetsare polymers whose individual chains have been chemically linked by covalent bonds during polymerization or by subsequent chemical or thermal treatment during fabrication. Once formed, these crosslinked networks resist heat softening, mechanical deformation, and solvent attack, but cannot be thermally processed. Such properties make thermosets suitable materials for composites, coatings, and adhesive applications. Principal examples of thermosets include epoxy, phenol–formaldehyde resins, and unsaturated polyesters that are used in the manufacture of glass-reinforced composites such as Fiberglas

                                                    e.g. Urea formaldehyde, Melamine formaldehyde.

                                     

                                    

4 On the basis of geometrical structure of polymer:

(i) Straight: Having no branching in the polymer backbone.

                                e.g. polyethylene

(ii) Branched: Having branching in the polymer backbone.

                                e.g. PVC, PVA,

(iii) Cross linked: Having cross-linked between and among polymer chain.               

                                  e.g.- Urea Formaldehyde, Melamine Formaldehyde

5 Based on form and use:

(i) Fibre: A fiber or staple fiber is a unit of matter which is usually at least 100 times longer than      its thick.                                     e.g. – Polyester, nylon

(ii) Elastomer: When vulcanized into rubbery products exhibiting good strength and elongation , polymers are used as elastomers.

                                      e.g. – Rubber

(iii) Plastics: When a polymer is shaped into hard and tough utility articles by the application of hear and pressure it is used as a plastic  

                                       e.g.  PVC

6. Based on monomer present:

(i) Homopolymer: When the unit are all the same and are joined linearly (a linear polymer), the polymer is a homo-polymer and it’s structure may be represented as [M] _n where M is the repeat unit and n is the no of repeat units or degree of polymerisation (D.P).

(ii) Co-polymer:  When more than one type of repeat unit is involved the polymer is called copolymer.                                          Example-PVC  

7. Based on the mechanism of Polymerisation:

(i) Chain Polymer: e.g. Polyetylene

(ii) Step or condensation:

8. Based on side chain present :

(i) Isolatic:   When a polymer chain grows if the vacanted orbits arranged at the same position all the time, incoming monomeric units are inserted with the same spatial arrangement resulting the isotatic polymer.

(ii) Syndoitactic:  When a polymer chain grows, the insertion of each monomeic unit if migrates from one position to the other er alternatively spatial arrangement resulting syndiotactic.

(iii) Alactic: When a polymer chain grows if the vacanted orbits arranged randomly is called alactic


In the next tutorial you will get total classification of polymerization. so stay with
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