Types of Plastics and their Properties.

We see different types of materials in our surroundings but most of those materials are made up of plastics.

Plastic is a popular, useful material but we use a lot of it.

About every 3rd object we see is made up of plastic.

Plastic is also a polymer like synthetic fibre.

That means plastic is made up of repeating unit which are bonded to each other.

But we need to understand that all plastics do not have the same types of arrangements.

The arrangement of the repeating unit in plastic results in linear and cross-linked structure.

Usually, there are two types of plastic-based on their reaction upon being heated.

One from the two types of plastic is thermoplastic

Take a normal polythene bag and start burning it slowly.

Apart from the noxious smell it produces.

We see it melts and we also see droplets of melted plastic fall off.

Such plastic which gets deformed easily on heating and can be bent easily are known as thermoplastics.

The constituent units of thermoplastic have a linear arrangement.

Being heated thermoplastic become soft.

Now they can be recast into different shape and cooled causing them to harden.

Without any chemical change of course!

Therefore they can be recycled. Some of the examples of thermoplastic are

Polythene, Polyvinyl-chloride, Polystyrene,etc

Thermoplastics are used in the manufacturing of water pipes, drain pipes, packaging, bottles.

Now the second type of plastic is Thermosetting plastic.

On the other hand, there are some plastics which when moulded once.

can not be softened by heating. These are called thermosetting plastics.

Thermosetting plastic has a cross-linked arrangement of their constituent elements.

Thermosetting plastics can be melted and take any shape we offer.

But they take the shape of what we offer only once and can never be reshaped again.

After they have solidified, they stay solid forever.

On Subsequent heating, they do not become soft and hence do not change their shape.

Which makes them impossible to recycle.

Bakelite and Melamine are two examples of the thermosetting plastic.

The familiar electrical switches, hands of utensils are made up of Bakelite.

As it is a poor conductor of heat and electricity.

Plastic has properties due to which it is preferred over other materials and so we find it everywhere.

Let us see the properties of plastic.

Plastic is light and has strength So it is used to make cars, aircraft and spacecraft

Metals like iron get rusted but plastics do not react and is not rusted when exposed to water and air.

That is why they are used to store various kinds of material specially chemicals.

Plastics are generally cheaper than metals. So they are widely used in industry and for household articles.

We know that plastics are poor conductors of heat and electricity.

That is why electrical wires have plastic covering, and handles of screw drivers are made of plastic

Plastics find extensive use in the healthcare industry.

Some examples of their use are the packaging of tablets,

used in syringes, doctors’ gloves and a number of medical instruments

Revision

The constituent units of thermoplastic have a linear arrangement.

Thermoplastics can be recast in different shape and cooled causing them to harden and can also be recycled.

Thermosetting plastic has a cross-linked arrangement of their constituent elements.

Thermosetting plastics take the shape of what we offer only once and can never be reshaped again.

Bakelite and Melamine are two examples of the thermosetting plastic.

That’s our end!