Polyethylene terephthalate

This is a special kind of plastic.

It is used to make many things. It makes clothes and clear bottles. It can even make shiny film.

We use it for soft drinks. It is very strong. It can hold many liquids.

We can recycle it to use again. Look for a small number 1.

This plastic helps us every day. Do you see it near you?

Polyethylene terephthalate is a very common type of plastic.

People often call it PET. When it is used to make cloth, it is called polyester. PET is used to make many things. It makes clothes like sportswear. It also makes clear bottles for soft drinks.

This plastic is made in a few ways. One way is a set of steps called a reaction. In this way, two parts mix together to make the plastic. Another way to get PET is to recycle old items.

PET can look different depending on how it is made. It can be clear like glass. It can also look white and cloudy. Some thin films made from PET are even used as space blankets.

PET is strong and hard to break. It is also easy to recycle. You can find a small number 1 on the bottom of PET bottles.

In 2020, the world made 82 million tons of PET. It is the fourth most common plastic in the world.

Polyethylene terephthalate is a very common type of plastic.

People often call it PET or PETE. When this material is used to make cloth, it is called polyester. It is a very important part of our modern world. In 2020, the world produced 82 million tons of it. It is actually the fourth most common plastic made on Earth. This is only behind polyethylene, polypropylene, and polyvinyl chloride.

Making PET is a step-by-step way of joining small parts together. Scientists use a thing called a reaction to build the plastic. One way involves mixing terephthalic acid with ethylene glycol. This can happen through a process called esterification. Another way uses dimethyl terephthalate and ethylene glycol through transesterification. During these steps, water or methanol is left over as a byproduct. Finally, a polycondensation reaction joins the units into a long chain.

People have been working with this material for a long time. J. R. Whinfield is credited with inventing the polyester fiber. He worked with James Tennant Dickson in England. They patented the material in 1941. A company called ICI first sold it as Terylene in the 1940s. Later, a company called E. I. DuPont launched the brand Dacron. In the Soviet Union, scientists developed a version called Lavsan in 1949.

PET can look and act in many different ways. It can be clear like a window if it is cooled quickly. This is called an amorphous state. If it cools slowly, it becomes semi-crystalline. This version can look white and cloudy.

It is very strong and can resist being broken. It is also used to make very thin films. Some of these films are even used for space blankets. These blankets reflect heat to keep things warm.

You likely use PET every single day without knowing it. It makes the clear bottles used for soft drinks.

It is also used in many types of clothing. Many people wear polyester sportswear or warm thermal layers. It is even used in car seats and 3D printing. Some people use a special version called PETG for 3D printing. It is even used to make parts for surgical tables. This shows how one material can do so many jobs.

Polyethylene terephthalate is a widely used thermoplastic polymer resin. It belongs to the polyester family of plastics. People often use the acronym PET or PETE to describe it. It is a highly versatile material used in many industries. In 2020, the global production of PET reached 82 million tons. This makes it the fourth-most-produced polymer in the world. It follows polyethylene, polypropylene, and polyvinyl chloride in total production volume.

Creating PET involves a series of chemical reactions to join small units. These repeating units have the chemical formula C10H8O4. One method uses an esterification reaction between terephthalic acid and ethylene glycol. This process produces water as a byproduct. Another method uses transesterification. In this version, ethylene glycol reacts with dimethyl terephthalate. This reaction produces methanol as a byproduct.

Following these steps, a polycondensation reaction occurs. This reaction joins the monomers into long polymer chains. This final step also releases water as a byproduct.

PET can exist in two different physical states. The first is the amorphous state. This occurs when the molten polymer is cooled very rapidly. Amorphous PET is transparent and clear. The second state is semi-crystalline. This happens when the molten material is cooled more slowly. In this state, the material forms many small crystallized areas called spherulites. Depending on the particle size, semi-crystalline PET can look transparent or opaque and white.

History shows how this material changed the textile and packaging industries. J. R. Whinfield and James Tennant Dickson patented PET in 1941 in England. The company ICI first commercialized it in the 1940s under the brand name Terylene. The name Terylene was created by inverting parts of the words poly(eth)ylene and ter(ephthalate). Later, E. I. DuPont launched the brand Dacron. In the Soviet Union, scientists developed a version called Lavsan in 1949.

In 1973, Nathaniel Wyeth invented the PET bottle, which was patented by DuPont.

The uses for PET are incredibly diverse. In textiles, it is known as polyester. It is used for clothing, sportswear, and automotive upholstery. In packaging, PET is used for rigid containers like soft drink bottles. To protect beverages like beer, manufacturers use a multilayer structure. They sandwich a layer of polyvinyl alcohol or polyamide inside the PET. This helps reduce oxygen permeability.

Flexible packaging also uses biaxially oriented PET, or BoPET. This film can be aluminized to create reflective surfaces. Such films are used in thermal insulation like space blankets.

PET also serves important roles in high-tech engineering. BoPET is used in the backsheets of photovoltaic modules for solar energy. It can also serve as a substrate in thin-film solar cells. In the automotive and aeronautical sectors, PET is used for various industrial parts. A special version called PETG is popular in 3D printing. PETG is used for high-end applications, such as surgical fracture tables. The surface of PETG can even be modified to be self-cleaning.

Scientists measure the quality of PET using intrinsic viscosity. This is a dimensionless measurement of the polymer's molecular weight. Different applications require different levels of polymerization. For example, textile fibers usually have an intrinsic viscosity between 0.40 and 0.70. Carbonated drink bottles require a higher viscosity, between 0.78 and 0.85. Engineering plastics and monofilaments require even higher levels, ranging from 1.00 to 2.00. This precision allows PET to be customized for almost any job.