Difference Between Thermoplastic and Thermosetting Plastics

You are having a car or watching television or gifting a toy to your child or even flying an aircraft, Plastic is everywhere. We can’t even think of our life without plastic. In plastic part design often we come across this confusion about Thermoplastic vs Thermosetting plastic. So in this article, we will explain about Difference between thermoplastic and thermosetting plastics.

What is Plastic

Plastic or in the chemical term we call it “Polymer” is formed when multiple monomers bond together using a chemical reaction. Molecules are bonded together to form plastics. Usually, monomers are made of carbon and hydrogen but it may also contain oxygen, nitrogen, and other gases.

Although there are natural polymers the recent industry trend is that businesses create their own commercial polymers as per their need. This helps them to get the required mechanical and chemical properties in the said plastic.

Commercial plastics use additives, color, fibers, and other chemicals to get enhanced properties that are suitable for different applications. In this article, we will find out the differences between Thermoplastics and thermosetting plastics.

Difference Between Thermoplastic and Thermosetting Plastics

This is the confusion among many engineers when they get into the plastic part design or plastic mold design. Although both sound similar but both have a major difference in the way they respond when the heat is applied.

What is Thermoplastic

Thermoplastics are polymers which when heated get melted and form the desired shape. It can be re-melted and it can get a different shape. So thermoplastic can be used and formed multiple times without hampering the chemical or mechanical properties up to some extent.

Thermoplastics are recyclable as can be used multiple times. The melting point is comparatively low. This kind of plastic offers more ductility and can absorb impact load very well. They are very sensitive to heat and not used where extreme heat is encountered.

Difference Between Thermoplastic and Thermosetting Plastics

Most of the plastic that we see in our day to day life is Thermoplastic. In fact, 80% of the polymers found in the market are Thermoplastics. Though it’s costlier than thermosetting due to its recycled nature and properties to mold into anything makes it an ideal choice for industries.

Though thermoplastics can be melted and molded multiple times with each cycle it loses its properties. So there is a limit on how many times you can remold thermoplastics. When we use re-melted plastics in the mold we call it to regrind plastic. It’s an industry standard to use 10% regrind plastic and 90% virgin plastic in major applications.

Advantages Of Thermoplastics

  • Can be remolded multiple times
  • Can take any shape
  • Additives, color, fibers can be added easily
  • Regrind possible.
  • Reshaping capabilities available.
  • Offers good impact resistance
  • Usually chemical resistant
  • A superior finish is possible.
  • Can be molded with other polymers
  • Wide range of commercial applications.

Disadvantages of Thermoplastics

  • Not suitable for the high-temperature zone.
  • Not strong enough to withstand enough load
  • Regrind possible only for a few times.
  • Gets melt easily under heat
  • Costlier than thermosetting

Example of major commercial Thermoplastics

  • ABS- Acreno butadiene styrene
  • HIPS- High impact polystyrene
  • PC- Polycarbonate
  • PE-Polieyhelene
  • PP-Polypropylene
  • PVC- Polyvinyl chloride
  • PS- Polystyrene
  • Nylon

Also read : Two plate mold vs Three plate mold

What is Thermosetting plastics

Thermoset plastics get melted when the heat is applied and get the desired shape. But it can not be remelted due to the cross-linking polymerization. Thermoset plastics once molded are unaffected by any solvent or heat.

Thermoset plastics are usually brittle in nature and can not absorb impact loading, however, static loading capacity is great. So thermosets are usually used where static loading is of importance.

Difference Between Thermoplastic and Thermosetting Plastics

Since Thermoset plastics can withstand heat, often those are used where extreme heat might get encountered like home appliances, electronic products, etc. This type of plastic is also used in sealant applications as they don’t deform over time or temperature.

It’s a recent trend to use Thermoset plastic over metal as the load-carrying capacity of thermosets can be compared with metals. Though this type of transition is not very popular industries are moving away from metals to save on material cost and manufacturing cost.

Advantages of thermosets plastics

  • Can withstand enormous heat
  • Does not deform or melt when heat is applied
  • Excellent strength and load-carrying capacity.
  • An excellent option to replace metals.
  • Cost-effective plastic

Disadvantages of Thermoset plastics

  • Can not absorb impact loading
  • More of a brittle in nature than ductile
  • Greater finishes not possible.
  • Can not be remolded.
  • Can not be recycled.

Example of commercial Thermoset plastics

  • Melamine
  • Bakelite
  • Epoxy resins
  • Phenolic resins
  • Polyesters

Difference Between Thermoplastics and Thermosetting plastics: Comparison

Sl #ThermoplasticsThermosetting
1They are liner polymersThey are crosslinked polymers
2Can be reused multiple timesCan not be reused
3Low melting pointHigh melting point
4Low strengthHigh strength
5High impact resistanceLow impact resistance
6Not fireproofUsually, fireproof up to some extent.
7No chemical reaction during mouldingUndergo chemical reaction during moulding
8Ductile in natureBrittle in nature
9Affected by solventNot affected by solvent
10More varieties of plastics availableLess varieties of plastics available


Both thermoplastics and thermosets are widely used in commercial applications and both have their pros and cons. The primary difference between Thermoplastics and thermosetting plastics is how they respond to heat due to the chemical structure.

If there is one major difference that distinguished both plastics is that Thermoplastic can be reused but Thermoset plastic can not be.

I hope you had a fair amount of idea about the difference between Thermoplastics and thermosetting plastics If you still have questions or doubts then do write in the comment section and we can take it forward from there.


A 2004 batch Mechanical Engineering graduate From NIT, Agartala. Close to 16 years of experience in the field of consumer electronics and appliances domain as a Sr. Design Engineer and Team Leader in India and the United States. A GD&T practitioner, with expertise in Lean Manufacturing and Six Sigma. Crazy about exploring CAD-CAM tools and in his free time love to go for a ride with his champ, Rian.