Difference between thermoplastic and thermosetting plastic with examples and uses
Plastics are synthetic polymers made of various monomeric units. We use plastics in almost every field of life. All plastics do not have the same type of arrangement of monomeric units. In some monomeric units, the arrangement is linear, whereas in others, it is cross-linked. Polythene is an example of a plastic. It is used for making commonly used polythene bags. Plastic can be classified as thermoplastic and thermosetting Plastic. Keep reading to know more details about thermoplastic.
What is Plastic?
Plastic is a polymer consisting of synthetic or semisynthetic organic compounds. Some plastic can be shaped when soft and then harden to keep the given shape.
Types of Polymers
1. Based on molecular force
Elastomer
Fibres
Thermoplastic
Thermosetting plastic
2. Based on occurrence
Natural
Semi-synthetic
Synthetic
3. Based on structure
Linear
Branched
Cross-linked
4. Based on thermal behaviour
Thermoplastic
Thermosetting plastic
What is Thermoplastic?
Thermoplastic is a plastic that has a strong force of attraction. These types of plastic become soft on heating and become hard on cooling. These types of plastic can be reshaped and remelted into a variety of shapes.
Common examples of thermoplastic are polyester, Teflon, polystyrene, and polypropylene.
Types of Thermoplastics
There are various types of thermoplastics. Below is the list of some thermoplastics.
Polyethylene terephthalate (PET) is one of the most easily recyclable plastics and it has excellent moisture and a barrier.
Polyvinyl chloride (PVC) is constituted by the polymerization of vinyl chloride. It is versatile plastic and used for packaging and the paper industries. It is resistant to wear and tear.
Polypropylene (PP) is made of polymerization of propane. It is a partially crystalline and nonpolar compound. This polymer is produced by the chain growth polymerization reaction.
High-density polyethylene (HDPE) is formed by the polymerization of ethylene. It exhibits less branching that's why it has a high density.
Low-density polyethylene (LDPE) is also made by polymerization of ethylene but it shows less branching than high-density polyethylene.
What is Thermosetting Plastic?
Thermosetting plastic is a polymer that is obtained by irreversible stiffening a solid soft and liquid prepolymer. Thermosetting plastic is also known as a thermoset. Examples of thermosetting plastics are bakelite and vulcanised rubber.
Types of Thermosetting Plastic
Listed below are some of the thermosetting plastics.
Epoxy Resin - These types of plastic contain an epoxide group. These are formed by the reaction of two or more compounds and emit heat and change the material from liquid to granular solid.
Melamine Formaldehyde - These types of plastics are obtained by polymerization of the monomer unit called formaldehyde with melamine. It hardens when heated after the setting can't be changed to a different shape.
Polyester Resin - Polyester resin is formed by the reaction of organic acids and polyhydric alcohols.
Urea-formaldehyde - Urea formaldehyde is formed by the polymerization of urea and methanol. These types of polymers have more hardness and high modulus.
Difference Between Thermoplastic and Thermosetting Plastic
Conclusion
Plastics are polymers of organic compounds. These can be divided into various types. The two most important types of plastics are thermoplastic and thermosetting plastics. This classification is based on the thermal behaviour of plastics. Thermoplastics are used for manufacturing toys, combs, and various types of containers as they can be remould after heating. Thermosetting plastics are used for making electrical switches, handles of various utensils, etc. as these plastics don’t soften on heating.
FAQs on Thermoplastic and Thermosetting Plastics Explained
1. What is the difference between thermoplastic and thermosetting plastic?
The main difference between thermoplastic and thermosetting plastic is that thermoplastics can be melted and reshaped repeatedly, while thermosetting plastics cannot be remelted once set.
- Thermoplastics soften on heating and harden on cooling due to weak intermolecular forces between polymer chains.
- Thermosetting plastics form strong cross-linked covalent bonds during curing, creating a rigid three-dimensional network.
- Thermoplastics are recyclable; thermosets are generally non-recyclable.
- Examples: Polyethylene (PE) is a thermoplastic; Bakelite is a thermosetting plastic.
2. What are thermoplastics?
Thermoplastics are polymers that soften on heating and harden on cooling without undergoing chemical change.
- Their polymer chains are held together by weak intermolecular forces.
- They can be melted, reshaped, and recycled multiple times.
- They are generally flexible and lightweight.
- Common examples include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), and polystyrene (PS).
3. What are thermosetting plastics?
Thermosetting plastics are polymers that become permanently hard and rigid after heating due to cross-linking.
- During heating, they undergo a curing reaction that forms strong covalent cross-links.
- Once set, they cannot be melted or reshaped.
- They are heat-resistant and structurally strong.
- Examples include Bakelite, melamine, and epoxy resins.
4. Why can thermoplastics be reshaped but thermosetting plastics cannot?
Thermoplastics can be reshaped because they have linear or slightly branched chains with weak intermolecular forces, whereas thermosetting plastics have strong cross-linked covalent bonds.
- In thermoplastics, heating overcomes weak forces, allowing chains to slide past each other.
- Cooling reforms the weak forces without chemical change.
- In thermosets, cross-links create a rigid three-dimensional network.
- Reheating thermosets breaks chemical bonds instead of softening them.
5. What are the types of thermoplastics?
The main types of thermoplastics include commonly used linear and branched addition polymers.
- Polyethylene (PE) – used in plastic bags and bottles.
- Polypropylene (PP) – used in containers and automotive parts.
- Polyvinyl chloride (PVC) – used in pipes and cables.
- Polystyrene (PS) – used in packaging and disposable cups.
- Polyethylene terephthalate (PET) – used in beverage bottles.
6. What are the examples of thermosetting plastics?
Common examples of thermosetting plastics include Bakelite, melamine, epoxy resins, and urea-formaldehyde.
- Bakelite – used in electrical switches and handles.
- Melamine – used in kitchenware and laminates.
- Epoxy resins – used as adhesives and coatings.
- Urea-formaldehyde – used in plywood and molded objects.
7. How are thermoplastics and thermosetting plastics formed?
Thermoplastics are usually formed by addition polymerization, while thermosetting plastics are typically formed by condensation polymerization with cross-linking.
- In addition polymerization, monomers like ethene form polymers such as polyethylene: nCH2=CH2 → (–CH2–CH2–)n.
- In condensation polymerization, small molecules like water are eliminated.
- Thermosets undergo further cross-linking during curing, forming a rigid structure.
8. What are the properties of thermoplastics and thermosetting plastics?
Thermoplastics are generally flexible and recyclable, while thermosetting plastics are rigid and heat-resistant due to cross-linking.
- Thermoplastics: low to moderate melting point, recyclable, softer, less brittle.
- Thermosets: high thermal stability, non-recyclable, hard, brittle, chemically resistant.
- Thermosets have better dimensional stability at high temperatures.
9. Can thermosetting plastics be recycled?
Thermosetting plastics cannot be recycled by melting because they contain permanent cross-linked covalent bonds.
- Reheating does not soften them.
- Excessive heat causes decomposition instead of melting.
- They may be mechanically ground and reused as fillers, but not remolded.
10. What are the uses of thermoplastic and thermosetting plastic?
Thermoplastics are used where flexibility and recyclability are needed, while thermosetting plastics are used where heat resistance and strength are required.
- Thermoplastics: packaging materials, bottles, toys, pipes, storage containers.
- Thermosetting plastics: electrical insulators, circuit boards, adhesives, laminates, cookware handles.
- Thermoplastics are common in consumer goods; thermosets are preferred in high-temperature or structural applications.
