Have a look around your surrounding and think for a moment. You will realize that most of things that you see are made up of plastic: chairs, tables, toys, cups, synthetic clothing material and the list goes on. We are talking about plastics because it is an essential element for human survival and plastics are made up of polymers. Classification of polymers is necessary as its demand and use are ever increasing.
Let’s start with an introduction to polymers; the word ‘polymer’ has been derived from two Greek words: poly which means many and ‘mer’ means unit. So, we can define polymer as something which is composed of many repeating units. In reality, polymer is defined as very large molecules that have high molecular mass and so they are also referred to as macromolecules. Macromolecules are ones which are formed by joining of repeating structural units and this repetition takes place on a very large scale.
Let’s move on to classification of polymers. Polymers cannot be classified under one category because of its several usages and different behaviors and structures. We can therefore classify it on the basis of the following considerations:
Classification of polymers based on origin
There are three types of classification under this category.
- Natural polymers: These are polymers which occur naturally and are found in plants and animals. For example: proteins, starch, cellulose and rubber. To add up, we also have biodegradable polymers which are called bio polymers; this will be discussed here a little later.
- Semi – synthetic polymers: They are derived from naturally occurring polymers and undergo further chemical modification.
- Synthetic polymers: These are man-made polymers. Plastic is the most common and widely used synthetic polymer. It is used in industries and various daily products.
Classification of polymers based on structure
This category has the following classifications:
- Linear polymers: The structure of polymers containing long and straight chains fall in this category. PVC, i.e. poly-vinyl chloride is largely used for making pipes and electric cables, is an example of a linear polymer.
- Branched chain polymers: When linear chains of a polymer form branches ,then such polymers are categorized as branched chain polymers. Low-density polythene is an example of branched chain polymers.
- Cross-linked or network polymers: These polymers are composed of bi-functional and tri-functional monomers. They have a stronger covalent bond as compared to various linear polymers. Bakelite and melamine are examples in this category.
We have classified the general polymers, but missed out on one and that is bio polymers. Bio polymers, as the name suggests is obtained from the living organisms. In a broad sense we can also say that these are biodegradable polymers. There is a difference between the synthetic polymers and the bio polymers; the structure is very well defined in case of bio polymers. Bio polymers include various bio molecules for instance carbohydrates and proteins. These molecules fold into characteristic shapes as found in protein molecules where folding occurs.
The polymers which are stable at high temperature are known as high-temperature polymers. The molecular weight of these polymers is high so that they are not destroyed at high temperature. These polymers find an extensive application in the health care industry. They are used for making sterilization equipments and is an important part of the chemical industry. High temperature polymers also find application in the manufacturing of heat and shock-resistant objects. To know more about classification of polymers, bio polymers and high temperature polymers kindly install our app, the Byju’s learning app.