Back in 1937, the initial research on polyurethane polymers started in Germany. Researchers focused mostly on producing flexible fibers and foams. However, the product that we know today as polyurethane foam (PU foam) did not become available for commercial production until 1954.
The production process for polyurethane foam usually involves adding small amounts of blowing agents (which are volatile) to chemicals. This reaction will result in a lower density, higher energy absorption, and an increase in thermal insulation to the base material. The blowing agents aerate the base chemical, similarly to how baking soda aerates bread. The process of producing PU can be “bottled”. This is why you can buy sheets/blocks of PU foam or containers filled with the liquid mix that expands into foam after it is sprayed.
The health risks for polyurethane foam are minimal. The closed cells of the foam can open and release gas over time, which sometimes causes unpleasant odors. It is also recommended that adequate protection is used when spraying PU foam because it has been linked to respiratory problems. Besides this, PU can be highly flammable but in virtually all its forms it contains a fire retardant. The fumes from burning PU, however, can be highly toxic.
Uses as Insulation
Because of its high R-value, polyurethane foam is widely used for insulation. It can be found in rigid panels or spray foam. Spray foam is more versatile than the rigid panels. Panels have to be cut to the perfect shape to properly insulate. Spray foam, on the other hand, fills hard to reach nooks and crannies and gaps created by pipe or wire penetrations. Spray foam also helps to prevent mold growth and reduce the load on your HVAC system.
PU foam can also be sprayed onto surfaces, and it is widely used to insulate ships and boats. PU foam acts as both insulation and a corrosion inhibitor by filling in water traps and preventing condensation in gaps within the hull.
The chemical formula of PU can be tweaked and adjusted to get the right ratio of density, flexibility, and hardness. This means that polyurethane can suit a wide range of applications, including:
- Seating in automobiles, aircraft, trains and even furniture
- Resin transfer molding cores
- Paint and print rollers
- Footwear liners
- Structural cores for marine vessel construction
The Future of Polyurethane
Polyurethane foam has been a great benefit to our world and is continuously being improved. Engineers are looking for new applications of the foam while improving the formula.