Polyurethane facts for kids

Plastic pipe with insulation. The red pipe, and the black mantle are made of polyethylene, the yellow-brown foam is made of polyurethane

Polyurethane is a polymer. Its name is often shortened to PU or PUR. A polyurethane is typically produced by reacting a polymeric isocyanate with a polyol.

In 2008, the global consumption of polyurethane raw materials was above 12 million metric tons, and the average annual growth rate was about 5%.

When did polyurethane appear?

Prof. Otto Bayer in 1952 demonstrating his creation

The story of polyurethane begins in the early 20th century. Scientists were experimenting with different ways to combine chemicals, and in the 1930s, they discovered a way to create a new type of plastic using isocyanates and polyols. These are long chemical names, but basically, they're the key ingredients in the polyurethane "recipe." Otto Bayer, a German chemist, is often credited with much of the early work on polyurethane, laying the groundwork for its future widespread use. The first patents related to polyurethane were filed around 1937.

How is polyurethane made?

A kitchen sponge made of polyurethane foam

Imagine mixing two special ingredients together – that's basically what happens when polyurethane is made. These ingredients are called isocyanates and polyols. When they're mixed, a chemical reaction happens, and this reaction creates long chains of molecules that link together to form the polyurethane.

The exact properties of the final polyurethane depend on the specific isocyanates and polyols used, as well as other additives that might be included. These additives can change the color, flexibility, hardness, and other characteristics of the final product. It's like adding different spices to a recipe – each one changes the final taste!

Different types and uses

Polyurethane comes in many forms, each with its own special properties and uses. Here are a few examples:

• Flexible Foam: This is the type of polyurethane you probably find in your furniture cushions, mattresses, and pillows. It's soft, comfortable, and provides good cushioning. The flexible foam is created by adding specific chemicals that make the polyurethane chains more flexible and less rigid. This type of foam is often used in car seats, too. The production of flexible foam involves carefully controlling the reaction between the isocyanates and polyols to create a material with the right balance of softness and support. Millions of tons of flexible polyurethane foam are produced globally each year.

• Rigid Foam: This is a much harder and denser type of polyurethane. It's often used as insulation in buildings and refrigerators. Its excellent insulating properties help keep buildings warm in winter and cool in summer, saving energy and reducing energy bills. Rigid foam is also used in packaging to protect fragile items during shipping. The production of rigid foam involves using different isocyanates and polyols, and often adding blowing agents to create a foam structure with many tiny air pockets that trap heat.

• Elastomers: These are rubber-like materials that are strong, durable, and flexible. They're used in things like shoe soles, wheels, and seals. Elastomers are known for their ability to withstand repeated stretching and bending without breaking. The production of elastomers involves carefully controlling the cross-linking of the polyurethane chains to create a strong, flexible network.

• Coatings: Polyurethane can also be used as a coating for many surfaces. It can protect surfaces from scratches, wear and tear, and it can also provide a beautiful finish. Polyurethane coatings are used on floors, furniture, and even cars. The production of polyurethane coatings involves dissolving the polyurethane in a solvent to create a liquid that can be applied to a surface. The solvent then evaporates, leaving behind a hard, protective coating.

• Castings: Polyurethane can be poured into molds to create various shapes and objects. This is used to make things like wheels, gears, and other mechanical parts. The process involves carefully controlling the reaction between the isocyanates and polyols to ensure the polyurethane cures properly within the mold.

Polyurethane and the environment

Like many materials, the production and disposal of polyurethane can have an impact on the environment. However, advancements in polyurethane technology are leading to more sustainable options. Some manufacturers are developing bio-based polyurethanes, which use renewable resources instead of fossil fuels. Recycling polyurethane is also becoming more common, with some companies developing methods to reclaim and reuse polyurethane waste.

Polyurethane in everyday Life

You probably encounter polyurethane every day without even realizing it. Think about your shoes, your furniture, your car, your refrigerator – all of these things might contain polyurethane. It's a truly versatile material that plays a significant role in our modern lives.

Images for kids

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  MDI isomers and polymer

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  Polyurethane foam made with an aromatic isocyanate, which has been exposed to UV light. Readily apparent is the discoloration that occurs over time.

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  A high-pressure polyurethane dispense unit, showing control panel, high-pressure pump, integral day tanks, and hydraulic drive unit

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  A high-pressure mix head, showing simple controls (front view)

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  A high-pressure mix head, showing material supply and hydraulic actuator lines (rear view)

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  A low-pressure mix head with calibration chamber installed, showing material supply and air actuator lines

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  Low-pressure mix head components, including mix chambers, conical mixers, and mounting plates

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  5-gallon (20-liter) material day tanks for supplying a low-pressure dispense unit

See also

In Spanish: Poliuretano para niños