Polyurethane (PU) is a thermoplastic polymer with good mechanical properties and excellent elastomeric properties. Its industrial uses range from construction to medicine.
This article provides an overview of polyurethane resins and their usage in composite, adhesive and coating applications specific to construction, marine and more general moulding applications. For a more general overview, readers should not neglect to consider medical, space, automotive and aerospace sectors.
What is Polyurethane Resin?
Polyurethanes are a class of block copolymers. They are synthesized from three different reagents: a polyol, a di- or multi-isocyanate, and a chain extender.
In contrast to epoxies, they can be either thermoplastics or thermosets.
In many cases they are block copolymers containing chemically connected hard and soft blocks (segments).
Uses of Polyurethane
Polyurethanes (PUs) are used either alone or as constituents of composites, coatings and adhesives. They are also used as foams and varnishes – applications discussed elsewhere.
The video below shows some of the lining and coating applications of polyurethane resin.
History of Polyurethanes
Polyurethanes were developed by Otto Bayer in 1938. DuPont led the commercial manufacture under the Lycra® brand. Since then, the number of polyurethane types and applications has expanded considerably.
Reinforcements
The inclusion of a reinforcement material expands and enhances the properties of a polyurethane system.
The type of reinforcement is application-specific.
For instance, resin-bound driveways use aggregate, which provides a higher level of mechanical strength to complement the more flexible and softer nature of polyurethane. This creates a more durable material that avoids the brittleness of epoxy. On the other hand, roofing applications might use a textile fabric. This makes it ideal for structures like roofs that can undergo a degree of structural movement.
