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Thermoplastic and Thermosetting Plastic

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Last updated date: 23rd Apr 2024
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Introduction

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 

Thermoplastic

Thermosetting plastic 

These types of plastics are low in molecular weight. 

These are higher in molecular weight compared to thermoplastic.

Thermoplastics are formed by the process of addition polymerization. 

Thermosetting plastic is formed by the process of condensation polymerization.

These types of plastics have a low melting point and low tensile strength. 

These types of plastics have more melting point and more tensile strength.

These plastics have a weak force of interaction among chains. 

These plastics exhibit a strong force of attraction among chains.

These plastics can be reshaped and softened again.

These plastics cannot be softened and revamped again once formed. 

Here monomer is generally bifunctional. 

The monomer is generally polyfunctional.

They are soft, brittle, and weak.

These are hard, strong, and more brittle. 

Example: polyvinyl chloride, polyethylene. 

Example: urea formaldehyde, melamine formaldehyde.


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.

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FAQs on Thermoplastic and Thermosetting Plastic

1. Write the characteristics of thermoplastic.

The following are the characteristics of thermoplastics:

  • The chains in the polymer are associated with intermolecular forces.

  • On heating these types of plastics, the molecular force becomes weak and converts into liquid if high viscosity.

  • These polymers can be converted into a different shape.

  • These are light weighted and strong polymers.

  • These are recyclable plastics.

  • They act as a flame retardant.

  • These types of plastics are good heat and electricity resistant.

2. What are the uses of thermosetting plastics?

There are various uses of thermosetting plastics in day-to-day life:

  • These are used in the manufacturing of various automobile equipment such as for making brake pistons.

  • These are also used in various agricultural equipment motors and feeding troughs.

  • They are used to make various heat shielding devices.

  • They are used in the manufacturing of a wide variety of permanent parts in industries.

  • These are used in manufacturing gas and water pipelines.

  • These are also used in the production of medical equipment.

3. Give five examples of thermoplastic.

Polyethylene, polyvinyl chloride, Polyethylene terephthalate, Teflon, and acrylic are some examples of thermoplastic.

4. What type of material is plastic?

Plastics are polymers formed by the polymerization of the monomeric unit. Plastic may be semisynthetic or synthetic.