Polyurethane (PU) is a polymer composed of organic units joined by carbamate (urethane) links. Generally it consists of single/two phases, the first phase may be a solid polymer matrix/gaseous phase matrix and the second phase may be present as foam in the form of fillers/fibers or other form.
Polyurethanes are versatile, modern, and safe. The polyurethane foams are chemically resistive to low range of pH levels and can withstand high temperatures. They can get back to normal stage without any adverse effect. Polyurethane foams are used in a wide variety of application to create all manner of consumer and industrial products that play a crucial role in making our lives more convenient, comfortable and environmentally friendly.
Polyurethanes are made by the exothermic reaction between alcohols with two or more reactive hydroxyl (-OH) groups per molecule (diols, triols, polyols) and isocyanates that have more than one reactive isocyanate group (-NCO) per molecule (diisocyanates, polyisocyanates) in the presence of suitable catalysts, surfactants, blowing agents, and additives. For example a diisocyanate reacts with a diol :
The group formed by the reaction between the two molecules is known as the ‘urethane linkage’. It is the essensial part of the polyurethane molecule
Polyurethane is combined with nylon to make more lightweight, stretchable garments. Over the years, polyurethanes have been improved and developed into spandex fibers, polyurethane coatings and thermoplastic elastomers.
The most common use for polyurethanes in major appliances is rigid foams for refrigerator and freezer thermal insulation systems. Rigid polyurethane foam is an essential and cost-effective material that can be used for meeting required energy ratings in consumer refrigerators and freezers thermal insulation systems. The good thermal insulating properties of rigid polyurethane foams result from the combination of a fine, close-cell foam structure and cell gases that resist heat transfer.
Polyurethanes are used throughout cars. In addition to the foam that makes car seats comfortable, bumpers, the car body, doors, and windows.
Polyurethane enables manufacturers to provide drivers and passengers significantly more automobile “mileage” by reducing weight and increasing fuel economy, comfort, corrosion resistance, insulation and sound absorption.
Building and Construction
Polyurethane’s excellent strength-to-weight ratio, insulation properties, durability and versatility makes it frequently used in building and construction applications. Both the affordability of these versatile materials and the comfort they provide homeowners have made polyurethane components part of homes everywhere.
Often referred to as “potting compounds”, non-foam polyurethanes are frequently used in the electrical and electronics industries to encapsulate, seal and insulate fragile, pressure-sensitive, microelectronic components, underwater cables and printed circuit boards.
Polyurethanes are commonly used in a number of medical applications, including catheter and general purpose tubing, hospital bedding, surgical drapes, wound dressings and variety of injection-molded devices. Their most common use is in short-term implants. Polyurethane use in medical applications can be more cost-effective and provide for more longevity and toughness.
Polyurethane packaging foam (PPF) can provide more cost-effective, foam-fitting cushioning that uniquely and securely protecting items that need to stay safely in place during transit. PPF is widely used to safely protect and transport many items, such as electronic and medical diagnostic equipment, delicate glassware and large industrial parts.