Polyurethane is used in millions of products. Everywhere that a “rubber” or plastic foam is needed, polyurethane is a candidate. One very large application is running shoes and other soles of shoes. Another large application is making structural members, such as beams and joists for buildings out of rigid polyurethane foams. Shoe soles wear down, becoming a polyurethane dust which suffuses our environment, much like rubber dust that comes off automobile tires (many of which are made of polyurethane too). But structural members are usually indoors, not worn down and not exposed to ultraviolet light so they have long lives, even possibly beyond the lives of the buildings they are in.

Pipe coverings are often made of polyurethane foam as are many pool toys or children’s toys. Foam fillings for pillows and furniture are normally polyurethane. The latter application leads to dangerous fumes during a fire as burning polyurethane releases cyanides into the air.

When a new use for excess polyurethane resins or light foams is sought, it is common to divert them into the very accommodating and low spec carpet backing industry.

It would make sense to build all applications for long, long lives, by building the polyurethane parts in such a way that they could be used over and over. For example, by making structural members a small percentage stronger than minimum specifications, and then adjusting the fasteners used for them to be easily removable (no cements used) , they could be reused in multiple buildings. This might require some standardization of the spans or members or spaces they are used in, rather than untethered, wild west custom specifications for each building.

Even shoe soles could be made replaceable in such a way that most of the plastic shoe was retained while only the sole was renewed. This challenging application would require some special research.

What is NOT very useful is a general plan for grinding up or otherwise modifying polyurethane into a degraded form that loses all sight of its original function as the part is destroyed to become barely a plastic material with no obvious function. And yet this is exactly the kind of research that occurs first to scientists who have been enthralled by the wasteful siren song of recycling. Consider this report: