Polyurethanes: Definition, Preparation, Properties and Application

What is Polyurethane?

Polyurethane (PU) is a polymer having organic units joined by urethane (also known as carbamate). Urethane is a compound that has an O-R group and an NH-R group bonded to the same carbonyl carbon.

Structure-of-Polyurethane

Polyurethanes are thermosetting polymers but their thermoplastic variants are also available in the market. Polyurethanes are prepared by the polymerization of toluene-2,6-di-isocyanate and ethylene glycol. If the reaction is carried out in the presence of a blowing agent, the product is polyurethane foam.

Preparation of Polyurethanes

Polyurethanes are formed by reacting a polyol (an alcohol with more than two reactive hydroxyl groups per molecule like ethylene glycol) and di-isocyanate or a polymeric isocyanate in the presence of suitable catalyst and additives.

Preparation-of-Polyurethane

Properties of Polyurethanes

1. Polyurethane has high load capacity in both tension and compression that may change shape under heavy load but will return to its original shape once the load is removed with little compression.

2. Polyurethanes possess high fear resistance along with high tensile properties.

3. Polyurethane material will remain stable with minimal swelling in water, oil, and grease.

4. Polyurethanes exhibit good electrical insulating properties.

Applications of Polyurethanes

1. Polyurethane foam is used for furniture stuffing, carpet backings, and insulation.

2. One of the most important uses of polyurethanes is in fabrics with elastic properties, such as spandex.

3. Polyurethane materials are commonly formulated as paints and varnishes for finishing coats t protect or seal the wood.

4. Polyurethane is also used in making solid tires and garments.

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