[Chemistry Class Notes] on Uses of Plastics Pdf for Exam

Polymers are long chains of molecules (mostly carbon) bonded to each other. The smallest molecule which has to be repeated again and again to form a long chain is called a monomer. In other words, a monomer is the repeating unit of a polymer.

 

Polymers can have a linear structure, branched or cross-linked structure. Most of the materials that are called Plastics are polymers. 

 

Plastic is a specific type of polymer that can change its shape. Plastics are made from petroleum. Many things around us are made of Plastics. For example Polythene, toys, bags, chairs, tables, boxes etc.

 

There are some well-known Plastics around us. They are polypropylene (chair, tables etc), polystyrene(Plastic spoons & forks, cups etc), polyamide (usually known as nylon) used in toothbrushes, car parts etc. Polythene is a very commonly used Plastic, mostly in the form of carrying bags.

 

Types of Plastics

There are two major types of Plastics based on their heat management nature. They are: 

 

1. Thermosetting Plastics

The Plastics which when cooled and hardened once lose their ability to change dimensions on heating are known as thermosetting Plastics. These Plastics retain their shapes and can not return to their original form i.e they are irreversible. This type of Plastic is used for making auto parts, aircraft parts etc.

 

Bakelite and melamine are some examples of thermosetting Plastics. Once they are given a shape and cooled, they cannot be melted again to form a new shape.

 

2. ThermoPlastics

Plastics that soften upon heating and return to their original form are called thermoPlastics. They can be moulded and remoulded again and again. ThermoPlastics are used for low-stress applications such as Plastic bags or high-stress mechanical parts. This type of Plastic is first heated and then cooled to get the final shape. The material can be reheated, reshaped and cooled repeatedly i.e thermoPlastics are recyclable. They do not lose their dimension changing ability.

 

For example, Polythene and poly-ethylene are the most commonly used thermoPlastics in our daily life.

 

Plastic Recycling

Recycling is a difficult process that involves many processing steps. Before recycling, we have to collect the Plastic material that is to be recycled i.e waste or scrap Plastic. Then, every Plastic item is separated according to its type because different types of Plastics must be processed in different ways and not all Plastics are recyclable. After this, washing has to be done to remove impurities that enhance the quality of the manufactured product. Cleaned and dried Plastic items are then melted at a regulated temperature and moulded into a new shape.

 

This reduces high rates of polluting land and water bodies. At the same time, recycling puts less pressure on virgin materials to produce new Plastic products.

 

Advantages of Plastics

Plastics of the following advantages over metals:

1. Plastics are highly flexible as compared to metals. For industries that need designing options, geometry and different kinds of textures, Plastics are going to be the most suited materials.

2. Plastics are cheaper as compared to metals. The manufacturing of Plastic parts is budget-friendly.

3. Plastics are highly durable and can last for an indefinitely long period. Metals, on the other hand, are much more prone to chemical and weather susceptibilities.

4. The specific gravity of Plastic is much lower making it an extremely lightweight material.

5. The manufacturing of Plastic is a faster process as compared to metals.

Uses of Plastics

Plastics are highly durable, lightweight and most importantly can be moulded into any form or shape. These properties account for the largest usage of Plastics. Plastics are extremely versatile materials and can be used for a wide variety of purposes. Some usage of Plastics are given below: 

1. The ability to be moulded makes Plastic ideal packaging material. Plastics in packaging help to keep foods safe and fresh.

2. Being durable and lightweight, Plastics have helped in the electronic field. From computers and cell phones to television and microwave, almost all appliances around us make some use of Plastic.

3. Plastics are used to make safety gear like helmets, goggles etc. Plastics are used in the construction industry due to their low maintenance and high durability.

4. Plastic is strong and lightweight, that is why it is useful in making toys, electrical switches and other household products.

5. Being non-reactive with air and water, Plastic is used to store water in Plastic bottles and other chemicals in chemical laboratories. 

6. Plastic is a poor conductor of electricity and heat. Its insulation property is used for coating the electric wire and to make handles of cooking utensils and various household products.

Fun Fact: 

John Wesley Hyatt invented the first synthetic Plastic in 1869. In 1907, Leo Baekeland invented bakelite which was the world’s first completely manufactured synthetic Plastic.