In the manufacturing world, urethane and polyurethane are often talked about interchangeably, despite them being different. When it comes to the science of the two compounds, they have slightly different chemical formulas. They are also used in different ways because their chemical formulas make them better for some uses and inappropriate for others. The two have different toxicity levels, too. Polyurethane is relatively safe, but urethane can be toxic for some animals and it can cause nausea when ingested by humans.
What is Urethane?
Scientifically, urethane is called ethyl carbamate or ethyl urethane. It is made by reacting a polyol and isocyanate. Polyols have a variety of functions based on the boiling temperature, viscosity, and polarity. Isocyanates are highly reactive chemicals with low molecular weight; these are commonly used in manufacturing as foams, fibers, and coatings.
When the polyols and isocyanates are combined in a chemical reaction, the resulting urethane can be molded into the shapes that manufacturers need for their projects.
What is Polyurethane?
Polyurethane is also a polymer made up of polyols and isocyanates that the urethanes link together. With the polyurethane, the urethanes are linked by polymerization, which happens when small monomers are combined to make a large molecule called a polymer. The monomers can be the same or can be made of different compounds. Usually, more than 100 monomers are combined to create products with elasticity, viscosity, tensile strength, or other necessary properties.
When making polyurethanes, only the isocyanate with one reactive isocyanate group is linked with alcohol that has two hydroxyl groups. This combination is what makes polyurethanes so versatile.
How Do Urethane and Polyurethane Differ from One Another?
When looking at the two words, it becomes easy to see how they are different. The prefix “poly” means many, so polyurethane has many urethane compounds. Meanwhile, urethane is on its own, as its own chemical group. Polyurethanes are composed of a variety of urethane groups. And they are modified to adjust the properties and qualities of the polyurethane.
When working with urethane, you will see that it can be both soft and rigid, giving it a very different use when compared to any polyurethane. For example, urethanes are commonly used in pesticides and insecticides.
Stated by polyurethane manufacturers, polyurethanes are used in very different ways compared to urethane. For example, polyurethane can be stiff and rigid, making it ideal for use in solid forms, like footwear, car parts, or factory parts. It is also commonly used as a flexible foam. Polyurethane is not as toxic and in many cases, it is not toxic at all. Polyurethane does not have a melting point, so it can withstand a wide range of temperatures because it is a thermoset polymer.
Benefits of Using Polyurethane
Polyurethane is a versatile material with mechanical properties that allow it to solve problems in a variety of situations. Polyurethane has a practically limitless list of uses that offer benefits and advantages that no other material has.
Better than Rubber and Plastic
Manufacturers appreciate polyurethane because it behaves like a combination of rubber and plastic. It has more durability than rubber, while also being harder than rubber. But, it has more flexibility than plastic. Because of this flexibility, polyurethane is stronger and more impact-resistance than both rubber and plastic.
Resistant to Impact and Abrasion
If you need a product that is resistant to wear and tear, polyurethane is it. The resistant qualities do not diminish at low temperatures either. Polyurethane has become popular when a product needs an abrasive-resistant material that works in a variety of environments. When compared to products made of plastics, metals, and elastomers, polyurethane has nearly ten times the abrasion and impact resistance.
Oil and Chemical Resistance
Many other materials struggle to retain their strength against oils and chemicals. Look at how easily steel rusts when exposed to water and air. Polyurethane remains stable when exposed to oil, water, and chemicals. In some instances, polyurethanes might swell slightly in some chemicals, but it still remains stable. Manufacturers that need an elastomer material that will maintain properties in chemical plants, subsea, and other wet conditions, polyurethane is the one to choose.
Multiple Manufacturing Uses
Polyurethane is an affordable material to use in manufacturing. It is used for prototypes, one-time parts, and one-off parts because of its flexibility. Polyurethane can be made into a limitless number of colors by adding pigments. And, ultraviolet shielding can be added to keep the colors constant. They can also be manufactured in weights that range from a few grams to over a ton.
Polyurethane’s Resilience
Because polyurethane has so much resilience, manufacturers turn to it when they need to make shock-absorbing products. The resilience of polyurethane makes it ideal for products that need to recover quickly and withstand high-vibration. Since resilience is a product of hardness, it can be manufactured in shore hardnesses that range from 20 SHORE A to 85 SHORE D on the Shore Durometer.
Maintains Shape
Polyurethane is a durable material that has several other qualities that manufacturers and customers appreciate. One is that it maintains its shape after being compressed. It might change while compressed, but it will return to its original shape. This recovery shows how flexible the material is and how it can be used in high-flex fatigue applications. It is also tear-resistant.
Bonding Properties
Manufacturers also appreciate the bonding properties of polyurethane. The material bonds to itself. And it bonds to materials like plastics and metals. It makes it useful in automotive manufacturing and products like wheels and inserts.
Polyurethane is a durable material that makes it useful in nearly any situation. It is even resistant to mold, mildew, and fungus, so it can be used in a wide range of environments, too. The product is affordable to manufacture and with subtle changes, polyurethane can be used as a foam, a rigid product, or a flexible one.