Plastic

Plastic is a man-made material.

It can be many shapes. We can mold it or press it. This lets us make boxes and bottles.

It is light and lasts a long time. People use it for toys and cars. It is also used for medical tools. Most plastic comes from gas or oil. Some come from plants. It can stay in nature for a long time. This can hurt the oceans. Many things are made of plastic every day.

Plastic is a material made by people. It is made of polymers. Polymers are long chains of tiny parts. These chains are made of many repeating units. Most of these chains use carbon atoms.

Scientists can change the chains to make new things. They add side chains to the main backbone. This helps change how the plastic feels or works.

There are two main kinds of plastic. The first kind is called thermoplastics. These can melt when they get hot. This lets people mold them into new shapes many times.

The second kind is called thermosets. These can only take shape one time. If you heat them again, they do not melt. They just break apart.

We use plastic for many things. About 40% is used for packaging. Other kinds are used for building houses.

Some plastics are very strong. They can even replace metal in cars. This makes cars lighter. However, most plastic is not reused. This can cause pollution in our oceans.

Plastic is a very useful material made by people. It is a type of synthetic material made of polymers. Polymers are long chains made of many repeating units called monomers. Most of these chains have a backbone of carbon atoms.

Scientists can change how a plastic works by adding side chains. These side chains hang from the main backbone of the polymer. They change how the material feels or behaves. Plastic is famous for its plasticity. This means it can be molded, pressed, or extruded into many shapes.

It is light, strong, and very cheap to make.

There are two main ways that plastics react to heat. The first group is called thermoplastics. These can melt when they get hot. This allows them to be molded into new shapes many times.

Common examples include polyethylene and polyvinyl chloride. The second group is called thermosets. These can only take a shape one time. Once they are solid, they stay that way even if they get hot again. If you heat them too much, they decompose instead of melting.

Some thermosets have closely cross-linked polymers that hold them together.

People have been making new kinds of plastic for a long time. The first fully synthetic plastic was called Bakelite. A man named Leo Baekeland invented it in New York in 1907. He was also the person who came up with the word "plastics." Since then, many scientists have helped us understand these materials. Hermann Staudinger is known as the father of polymer chemistry. Herman Mark is known as the father of polymer physics. Their work helped us learn how to build better materials.

We use massive amounts of plastic every single year. Between 1950 and 2017, humans made about 9.2 billion metric tons of plastic. In 2023, the world produced over 400 million metric tons. About 80% of this is called commodity plastic. These are cheap plastics used for things like food containers and toys.

Packaging is the biggest use, making up about 40% of usage. In India, packaging uses 42% of all plastic. In developed countries, about one third is used for packaging and building. Other uses include cars, which can be up to 20% plastic.

Plastic helps us in many ways, but it also causes problems. In cars, plastic can replace metal to make vehicles lighter. This can improve fuel efficiency by 6% to 8%. However, most plastic is not reused or recycled. Only about 9% of all plastics are recycled globally.

Much of it ends up in landfills or as pollution in the ocean. Some plastic even breaks down into tiny pieces called microplastics. These can hurt ecosystems and human health. It is a hard job to manage all the plastic we create.

Plastic is a vast category of synthetic or semisynthetic materials. These materials are primarily composed of polymers, which are long molecular chains. The defining feature of plastic is plasticity. This term refers to the ability of a material to be molded, extruded, or pressed into many different solid forms. This adaptability makes plastic incredibly useful for modern life. It is often lightweight, durable, and resistant to chemicals. Because it is inexpensive to produce, it is used in almost every industry worldwide.

To understand how plastic works, we must look at its molecular structure. Most plastics consist of organic polymers. These polymers are built from long chains of carbon atoms. These chains are made of many repeating units called monomers. The main path of the chain is called the backbone. To change how a plastic behaves, scientists add side chains. These side chains hang from the backbone and are attached to the monomers. The specific structure of these side chains determines the final properties of the material.

Scientists classify plastics in several different ways. One common method is by their chemical structure. This includes groups like acrylics, polyesters, silicones, and polyurethanes. Another method is by the chemical process used to make them, such as condensation or cross-linking. Plastics can also be grouped by physical properties. These properties include hardness, density, and thermal resistance. Some plastics are even classified by how they react to radiation or organic solvents.

A vital classification is based on how plastics react to heat. Thermoplastics are materials that do not undergo a chemical change when heated. They can be melted and molded into new shapes many times. Examples include polyethylene and polyvinyl chloride (PVC). In contrast, thermosetting polymers, or thermosets, can only take a shape once. After they solidify, they stay in that shape permanently. If you apply high heat to a thermoset, it will decompose rather than melt.

Thermosets often consist of closely cross-linked polymers that hold the structure together.

The history of plastic began in the early 20th century. The first fully synthetic plastic was Bakelite. Leo Baekeland invented Bakelite in New York in 1907. Baekeland is also the man who coined the term "plastics." Since then, many scientists have advanced the field. Hermann Staudinger is often called the father of polymer chemistry. Herman Mark is known as the father of polymer physics. Their work helped turn materials science into a sophisticated discipline.

Today, the scale of plastic production is enormous. Between 1950 and 2017, an estimated 9.2 billion metric tons of plastic were produced. More than half of that total was made since 2004. In 2023, preliminary figures showed over 400 million metric tons were produced. About 80% of this is known as commodity plastic. These are inexpensive plastics used for mass-produced items like packaging and food containers. In 2015, packaging alone consumed 146 million metric tons of commodity plastic.

Engineering plastics make up about 20% of global production. These are more expensive and much stronger than commodity plastics. They are often used in specialized applications like vehicle parts. In modern cars, plastic can replace metal to reduce weight. This can improve fuel efficiency by 6% to 8%. Even though cars are about 50% plastic by volume, plastic only accounts for 12% to 17% of the total vehicle weight.

Despite its benefits, plastic creates major environmental challenges. Most plastic produced has not been reused. Only about 9% of all plastics are recycled globally. About 14% of discarded plastic has been incinerated. This means much of it ends up in landfills or as pollution. An estimated 8 to 12 million tons of plastic enter the oceans every year. This pollution often creates garbage patches in the sea. There is also great concern regarding microplastics, which are tiny particles that can threaten ecosystems and human health.