Thermoplastic Vs Thermoset Polymers

Polymerization is a process in which thousands of smaller molecules called "monomers" join together to form larger molecules called "macromolecules/polymers". Polymers have higher molecular weight than monomers as they are formed by joining these monomer molecules. 

Several different categories of polymerization reactions exist, but the most notable of which are: step-growth polymerization and chain growth polymerization.

In this post, we will learn about two types of polymers which are classified on the basis of thermal properties and molecular forces present between them. These two types of polymers are Thermoplastic and Thermosetting polymers. 

Thermoplastic polymers–

1. Thermoplastic polymers or Thermo-softening plastics polymers are long chain polymers in which the polymeric chains are held together by the weak intermolecular forces (or Van-der waals forces). 
2. These types of polymers are formed by the addition polymerization or chain-growth polymerization reaction. 
3. The structure of these types of polymers are linear or lightly branched.
4. Examples of these types of polymers are poly-vinyl chloride, poly-styrene, polyethylene, etc.

While these polymers also show thermal behavior on heating. In general, when these polymers are heated, they soften easily due to their low melting point and can be recycled and reused with the application of heat.

Thermosetting polymers–

1. Thermosetting polymers or Thermoset plastics are polymers in which the polymeric chains are held together by the strong covalent forces (or by strong forces of attraction). 
2. These types of polymers are formed by the condensation polymerization or step-growth polymerization reaction. 
3. The structure of these types of polymers are cross linked or heavily branched. 
4. Examples of these types of polymers are bakelite, Urea formaldehyde resin, Melamine, silicones, vulcanized rubbers, polyesters, etc. 

In general, when these polymers are heated, they can be molded, shaped and hardened and once set, cannot be reshaped or recycled or soften even with the application of heat as these polymers have good heat resistance quality.

Difference between Thermoplastic and Thermosetting polymers–

1. Thermoplastic Polymers are synthesized by addition polymerization reaction whereas thermosetting Polymers are synthesized by condensation polymerization reaction.
2. In thermoplastic polymers, the polymeric chains are held together by weak van-der Waals interaction forces. Whereas in thermosetting polymers, the polymeric chains are held together by strong forces of attraction.
3. Thermoplastic polymers soften on heating and harden on cooling. Whereas thermosetting polymers do not soften upon heating.
4. Thermoplastic polymers are soluble in organic solvents whereas thermosetting polymers are insoluble in organic solvents.
5. Thermoplastic polymers have low melting point, due to that they lost their rigidity on heating and can be re-shaped and re-used. Whereas thermosetting polymers have high melting point, due to that they can withstand with high temperatures without losing its rigidity and cannot be re-shaped or re-used.
6. Thermoplastic polymers are mouldable or ductile in nature whereas thermosetting polymers are brittle and hard in nature.
7. Thermoplastic polymers are expensive than thermosetting polymers.
8. Thermoplastic polymers have a lower molecular weight than thermosetting polymers.
9. Examples of thermoplastic polymers are polystyrene, Teflon, acrylic, vinyls, nylons, etc. Whereas, examples of thermosetting polymers are vulcanized rubber, allyls, bakelite, polyurethane, epoxy resin, etc.

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