Plastics: Introduction, Types, Examples and Properties

Plastics are the common name given to a wide range of synthetic or semi-synthetic materials that contain polymers as a main ingredient. These materials can be moulded, extruded or pressed into solid objects of various shapes. Moreover, they are lightweight, durable, flexible, and inexpensive to produce. As a result of all these beneficial characteristics, their use has become widespread. However, the use of plastics have several disadvantages, the most severe of which is pollution. Additionally, plastics are conventionally derived from fossil fuel-based chemicals like natural gas or petroleum. However, recently new variants made from renewable materials, such as corn or cotton derivatives have also come up. Read on to learn more interesting facts about plastics.

What Are Plastics?

The word ‘plastic’ is derived from the Greek word ‘plastikos’ that means ‘fit for moulding’. The world’s first fully synthetic plastic invented in New York in 1907, by Leo Baekeland, and it was named Bakelite. Today, several different types of plastics are produced; for instance, polyethylene is widely used in product packaging, and polyvinyl chloride (PVC), because of its strength and durability are used in construction and pipes. Some examples of plastics are polystyrene, Teflon, vulcanised rubber, polyurethane, resins, etc. As plastics are easily moldable, we can make different plastic products. They are also easy to carry and are actively used in transporting goods. Due to its non-reactive nature, plastics do not corrode.Plastics are also called polymeric substances as they are capable of being moulded under application of heat and pressure. This property of getting moulded and shaped is called ‘plasticity’.

The special properties of plastics are that they are non-reactive, bad conductors of electricity, non-corrosive, transparent, tough, etc. These all properties of plastics together make them very useful for manufacturing a wide range of products. Some of the examples of plastics include PET (Polyethylene Terephthalate), PVC (Polyvinyl Chloride), LDPE (Low-density polyethene), HDPE (High-density polyethene), etc.

Types of Plastics

As we know that plastics are polymers, the various monomeric units are arranged in different patterns, i.e., linearly arranged or cross-linked. Thus, both types of monomeric units, as well as their arrangement, divides the plastics into different types.

If we heat a frying pan with a plastic handle and a simple plastic bottle, we will observe that the plastic bottle will melt immediately, and the frying pan handle will heat up without much physical change. This difference in behaviour is because both are made up of different types of plastics. The frying pan handle comprises thermosetting plastics, while the plastic bottle is made up of Thermoplastics. Let’s learn about them in detail.

1. Thermosetting Plastics – Heavily branched plastics that cannot be remoulded as they become hard on heating are known as thermosetting plastics. During manufacturing of such materials, plastics are cast in moulds, and once they become hard on cooling, they cannot be melted again.

Examples: melamine, Bakelite, urea-formaldehyde resins, etc.

1. As melamine can withstand high temperatures, it is used for making kitchenware, tiles.
2. Bakelite is a poor conductor of heat and electricity, so it is used for making handles of kitchen utensils, switchboards, etc.

2. Thermoplastics – The type of plastics that can be remoulded on heating as they melt and become soft and again become hard when cooled are known as thermoplastics.

Examples: Polythene, propylene, etc.

1. Polythene is used in manufacturing plastic bags, adhesive tapes, wires, toys, etc.
2. Hard Polyvinyl chloride is used in manufacturing construction pipes, while soft Polyvinyl chloride is used in manufacturing plastic bottles and containers that we use daily.

Properties of Plastics

1. Plastics are non-reactive. Due to this reason, they do not corrode as they do not react with water and air.
2. Plastics are easy to use as they are light, strong, and durable.
3. They can be moulded into various shapes.
4. Plastics are much cheaper than metals. Nowadays, plastic containers are very widely used.
5. Plastics are non-biodegradable, and on burning, they produce toxic gases that are very harmful to us and the environment.

Uses of Plastics

Plastics are very useful in all sectors of life. They are used in making several products. Some of them are discussed below:

Electrical Industry

Plastics are used to make the coverings of electric wires and handles of electrical tools, electric switches, etc., as they are poor conductors of heat and electricity. Apart from this, their durability and flexibility have made them an ideal choice for making safe, efficient, and reliable materials for such uses.

Plastic Containers

Plastics are highly resistant to chemicals and water, and this unique property makes them very useful in making airtight containers as food kept inside these containers do not get spoiled easily and can be stored for a long time. Plastic containers are of various forms like single-use, durable or recyclable plastic cups, glasses, bottles, airtight containers and many more. The complete packaging industry extremely depends on plastic containers.

Plastic Bottle Manufacturer

1. Plastic bottle manufacturing takes place in various stages. Plastic bottle manufacturers mostly use one of four types of plastic to produce bottles.
2. As polyethylene terephthalate (PET) is both strong and light, they are used to make plastic bottles for holding potable water.
3. High-density Polyethylene (HDPE) is used for making rigid and tough plastic bottles such as detergent bottles.
4. Low-density Polyethylene (LDPE) is used for making squeeze bottles.
5. Polypropylene (PP) is used for pill bottles for storing medicines.
6. Polycarbonate (PC) is used for manufacturing refillable water bottles and other reusable containers.

Plastic Bottle Manufacturing Process

In the first stage, plastic pellets are poured into ‘Reheat and Mould machine’ that heats them to a very high temperature, so that it becomes a thick liquid. This thick liquid of plastic is then injected into multiple-cavity moulds where it assumes the shape of long, thin tubes known as ‘parisons’ where the plastic hardens and sets into the shape of a bottle.

Plastic Recycling

Plastics are non-biodegradable materials. Each year about \(200\) million tonnes of plastics are produced, and if such a huge amount of non-biodegradable wastes is accumulated, our environment will be badly affected. So, the best option to deal with this problem is to recycle plastics. The melting and remoulding properties of plastics play a key role in recycling them.

Plastic Recycling Machine

Plastics are firstly sorted at recycling mills based on their size. Then high density and low-density plastics are separated by air pressure as there are a variety of plastics. Once sorting is over, the plastics are cleaned, and melted down and compressed into tiny pellets known as nurdles. These nurdles are ready to be reused and designed into new and completely different products.

Plastic Surgery

The process of reforming or repairing the body parts by the transfer of tissue, either in the treatment of accidental injury or for cosmetic reasons, is known as Plastic surgery. The term ‘Plastic surgery‘ is derived from the Greek word ‘plastikos’ meaning malleable or mouldable, and of course not because it requires the use of plastic. Silicone materials are mostly used as implants during plastic surgery. Thus, we should not confuse plastics and plastic surgery.

Summary

In brief, we can say that plastics are synthetic or semi-synthetic long chain polymers made up of repeating monomeric units having large molecular weight, mostly made up of organic compounds.

Based on the type and structure, plastics may be linear (Thermoplastics) as well as cross-linked polymers (Thermosetting). Strong and hard thermosetting plastics such as Melamine and Bakelite are used to make kitchenware handles, whereas soft and moldable thermoplastics such as polythene, PVC, etc., are used in manufacturing polythene bags, toys, pipes, and many more articles.

Though plastics being very useful in modern advancement and human development as they provide us with various valuable articles, it serves as a serious menace to our environment.

So, we should try our best to reduce, reuse and recycle plastic. Instead of recycling, whenever possible, we should try to minimise the use of plastics and reduce the level of environmental pollution caused by plastics. Very innovative use of waste plastics has come up as the construction of plastic roads.

Similarly such various measures should be taken to reuse and recycle plastics. Though we feel it is convenient to use and throw plastics, we should never forget the harsh effects it causes to our environment. Thus, we should use plastics in a very precocious manner.

FAQs on Plastics

The answers to the most commonly asked questions on plastics are given below:

We hope this article on ‘Plastics’ has helped you. If you have any queries, drop a comment below, and we will get back to you.