Elastomers

Introduction

At the molecular level, studying different materials is the job of a material scientist. These scientists study, research, and develop new materials which help shape modern industries. Depending on properties, composition, and other factors, all materials in this world are divided into various types and classes.

Polymers are a very interesting class of materials or substances that can be termed omnipresent. The term polymer is used to refer to substances whose molecules are large and consist of a large number of repeating portions or subunits. From natural presence in the human body to synthetic development over the years, polymers exist in various forms. They are used in an almost uncountable number of areas, and without them, our existence would come to a standstill; literally!

In this tutorial, we will discuss a special type of polymer known as an elastomer.

What are Elastomers? Explain with Examples.

Elastomers are polymers with two special properties.

• Firstly, as the name implies, they are elastic, i.e., they can be stretched without breaking and as soon as we let go, they go back to their original size.

• Secondly, they are viscous in nature. You can think of viscosity as the “thickness” of a certain fluid. For example, honey is more viscous than water. Scientifically, viscosity refers to the resistance of a material against deformation.

• Another property to keep in mind about elastomers is that the intermolecular forces in them are generally weak. This is what makes them so elastic since it allows them to stretch easily. The most common example of an elastomer is rubber. As you might have experienced, rubbers are easy to deform, and they quickly revert to their original size once we leave them be. Elastomers are also used to manufacture seals and adhesives.

Types of Elastomers

While elastomers have a large number of classifications, they can be broadly divided into two categories: thermoset, and thermoplastic. We will discuss these two types below

Thermoset Elastomers

These elastomers cannot be reshaped or remolded once they are manufactured even if we apply heat and pressure. They are highly resilient to a large variety of conditions. The name “thermoset” is given to these polymers since, after initial heat treatment, they get “set” and no longer get affected by heat.

You can think of thermoset elastomers as hard-boiled eggs. After hard-boiling, the eggs solidify and now, can no longer be reshaped.

Polyesters and silicones are two common examples of thermoset elastomers.

Thermoplastic Elastomers

These elastomers can be reshaped and remolded even after their initial manufacturing. All we need is some heat and we can reshape them as we please. Think of these elastomers as ice cream. Ice creams solidify but become liquid again upon taking out of the freezer. We can then re-freeze it into any shape we want.

Polyethylene, nylon, and PVCs are the most common examples of thermoplastics.

Properties of Elastomers

We have listed the three main properties of elastomers above. Let us discuss them in detail −

Viscosity

The viscosity of a substance is its ability to resist deformation. Viscosity is generally attributed to fluids and informally, you can think of viscosity as thickness. A glass of milkshake is “thicker” than water. That is, milkshake has a higher viscosity.

Elastomers have a higher viscosity than other polymers. And compared to common liquids we know of like water and honey, the viscosity of polymers is much higher. You can put this into perspective by imagining how “thick” rubber is as compared to water and honey.

Elasticity

Elasticity is the ability of a substance to stretch and revert to its original shape after the sources causing deformation are removed. Thus, rubber bands are highly elastic, whereas wood is much less elastic and might even break if too much force is applied.

Elastomers are associated with high elasticity. As previously mentioned, rubber is a type of elastomer, and you must have noticed how elastic rubber is. Elastomers are also used to manufacture adhesives.

Low Intermolecular Forces

All materials, whether solid, liquid or gaseous, are held together by intermolecular forces. These forces keep the molecules that make up the substance stay together. In elastomers, these forces are generally weak. This property is responsible for the high elasticity of elastomers since low intermolecular forces allow them to stretch easily.

Difference between Elastomer and Polymer.

Technically, elastomers are a subclass of polymers. Thus, instead of being different from polymers, they have some extra properties that not all polymers have. Here’s a summary −

Elastomers	Polymers
Elastomers are polymers with high viscosity and elasticity, and low intermolecular forces.	Polymers are materials that are formed by the repetition of large molecules hundreds and thousands of times.
All elastomers are polymers	All polymers aren’t necessarily elastomers.
Elastomers have high elasticity and viscosity.	The elasticity of polymers can vary depending on their structure.
Elastomers are amorphous polymers.	Polymers might be amorphous or crystalline.
Elastomers are flexible and can withstand pressure.	Polymers are generally rigid and break under pressure. Some polymers, like elastomers, are an exception to this property.

Application of Elastomers

The applications of elastomers are numerous. Not only are synthetic elastomers used in the industry and our day-to-day lives, but there are also natural elastomers without which, a large number of our daily tasks would not get completed.

• Natural rubber, derived from the rubber plant is an elastomer and is used to manufacture slippers and latex products.

• Silicone is also an elastomer that is used to manufacture an enormous number of items we use in our day-to-day lives.

• For example, a large number of baking products are made out of silicone so that they can withstand high temperatures.

• Elastomers are also used to manufacture rubber seals and adhesives. The tires used in cars and bikes are also manufactured from a variety of synthetic elastomers, as are the wipers used on car windshields.

Conclusion

Elastomers are a type of polymers characterized by high viscosity and elasticity, with low intermolecular forces. This means that they can stretch and revert to their original configuration without breaking. A common example of elastomers is rubber.

Elastomers are classified into thermoset and thermoplastic elastomers. The former of these become “set” after initial heat treatment and can no longer be remolded. The latter can be reshaped and remolded any number of times via the application of heat and won’t lose its original properties. Elastomers are a subclass of polymers and thus, aren’t technically different from polymers. They just happen to have a few extra properties which come in useful in a large number of applications such as car tires, windshield wipers, latex products, slippers, spandex, etc.

FAQs

Q1. Give an example of polymers that occur in the human body.

Ans. DNA chains inside the human body are an example of polymers.

Q2. What type of bond characterizes polymers?

Ans. Polymers are bonded via covalent bonds.

Q3. What are monomers?

Ans. Polymers are formed by large-scale repetition of a group of molecules or atoms. This group of atoms/molecules which, when repeated gives us the polymer is known as a monomer.

Q4. Inside a polymer, can multiple types of monomers exist?

Ans. Yes. A polymer can be made up of a single monomer, or it can be manufactured by the repetition of different types of monomers, giving rise to what is known as a copolymer.

Q5. Can the same monomer lead to different kinds of polymers?

Ans. Yes. Depending on manufacturing conditions, the outcome can differ significantly, leading to different kinds of polymers from the same monomer.