Thermosetting polymers or thermosets are prepared by a chemical reaction of at least two or more materials. One of the reactants is a monomer which forms the final chain of polymer. The second component is a cross-linker or comonomer which acts as a cross-linking substance. The cross-linker helps to combine 2 or more strands of monomers together. A generalized thermosetting process can be shown as follows:
Image-Thermosetting of uncross-linked polymer
For practical uses, thermosets are usually moulded for giving them a useful shape before they set into a hard form. There are a variety of ways in which these can be moulded, some being:
Reaction Injection Moulding (RIM): The two components required to make a thermoset are initially put into two separate tanks from which they are pressure fed into a mix-head. After mixing, they are fed into the mould. The final reaction and shape of the end product happens in the mould.
Resin Transfer Moulding (RTM)
We are not explaining each one in detail because that is out of scope of this article.
Thermosetting polymers have a cross-linked 3D structure. This structure inherently provides these polymers higher strength and breakage resistance. Some of the physical and chemical properties are also dependent on the components which are used to create the polymer. We list down some key properties below:
Thermosetting plastics are resistant to heat. But when very high heat is applied, they decompose before reaching melting point.
These are generally brittle in nature, because of loss of elasticity upon heating.
Once moulded or cured, these cannot be re-shaped by application of heat.
The density of thermoset is dependent on constituent components used to create the polymer.
Thermosets are generally resistant to chemical attacks.
As mentioned above, thermosets have some unique properties which make them highly useful for some of our day-to-day needs. Some of the common uses of thermosetting polymers are:
These are used to produce permanent parts for a wide range of industries.
Thermosets are used to produce electrical goods and components, including insulators and panels.
These are used to produce construction equipment panels.
Because they are heat resistant, they are used to produce heat shields.
In automobiles, thermosets are used to produce brake pistons.
These are used in multiple agricultural equipment including feeding troughs and motors.
Bakelite: Bakelite is phenol formaldehyde resin with monomer chemical formula of (C6-H6-O.C-H2-O). It is a brownish solid substance and was also the first plastic ever made with synthetic components.
Epoxy Resin: These are a class of polymers which contain epoxide groups. These are generally used in adhesives.
Melamine Resin: Also known as melamine formaldehyde, it is one of the most common plastics used to make kitchen utensils and other household products.
Duroplast: Duroplast is a fiber-reinforced plastic which is used to manufacture automotive parts. It is usually reinforced with cotton or wool.
Urea-Formaldehyde: As the name suggests, it is produced from urea and formaldehyde, and is used to make adhesives, boards and other moulded products.
So, this completes our topic on Thermosetting Polymers or Thermosetting Plastics or Thermosets. We hope you enjoyed learning about it. For more details and other topics, please log on to Vedantu website and download Vedantu learning app.