As the dealer hands over the keys, you slide into the driver’s seat of your new car, lean your head back, flip down the sun visor and place your hands on the steering wheel. You may not realize it, but nearly everything you’ve just touched is made of a special type of plastic called polyurethane.
Polyurethanes have been increasing automobile comfort and safety while decreasing energy use and road noise for more than 50 years.
Polyurethanes are a polymer composed of a chain of organic units, joined by urethane links. A highly versatile material, polyurethane can be very flexible, like foam seat cushions, or very rigid, such as exterior bumpers.
“Of course, Henry Ford’s first Model T did not roll off the assembly line in 1908 with the same modern comforts we enjoy in our vehicles today,” says Hamdy Khalil, senior global director-advanced technologies and innovation at Woodbridge Foam.
Early car seats were stuffed with horse hair, springs or wadding. Technological advances led to latex foam-rubber cushions, first installed in London bus seats in 1932.
Latex remained the material of choice for comfort until 1958, when General Motors started using polyurethane foam topper pads in the seats of some of its vehicles. The rest of the automotive industry followed suit.
“Polyurethane foams proved to be resilient, strong, lightweight, inexpensive to manufacture and easy to assemble,” Khalil says.
With more than 10.5 million light vehicles assembled in the U.S. and Canada during 2011, the automotive industry is a major consumer of polyurethanes. Your car at home may contain an average of 58 lbs. (26 kg) of the material.
Inside your car, headrests, seatbacks and seat cushions utilize a range of hard- and soft-polyurethane foams for optimum comfort and safety. Armrests, consoles, door handle pulls, gear-shift knobs and steering wheels are made of integral skin polyurethanes, which have a solid skin on the surface and cellular foam inside. Even the roof and floor – the car’s headliner and carpet underlay – contain polyurethane.
Polyurethanes also are at work outside your car and under the hood, comprising adhesives, coatings, primers, seals and gaskets.
“Molded polyurethanes give exterior body parts, including bumpers and door panels, an excellent strength-to-weight ratio,” Khalil says.
Here are a few ways that polyurethanes work behind the scenes to improve your driving experience:
- Comfort. In addition to supportive seats and headrests, polyurethane window seals and shock absorbers make a car more comfortable for drives long and short.
- Durability. Flexible polyurethane foam is designed to retain its shape over the lifetime of the car. In fact, polyurethane manufacturer The Woodbridge Group has tested vintage auto seat cushions salvaged from junk yards and found that even 10 to 15 years after manufacture, they still meet or exceed specification tests.
- Safety. In the event of an accident, polyurethanes play a huge role in energy absorption. Inside the car, polyurethane headrests minimize whiplash. Outside the car, polyurethane bumpers are specially designed to help absorb impact. Pillars made of polyurethane also absorb energy in a side collision.
- Weight reduction. Polyurethanes are lightweight by nature and can replace heavier traditional materials. For example, seat frames made from molded polyurethanes can be 35% lighter than metal stamped frames.
- Efficiency. Polyurethane’s lightweight structure reduces a car’s overall mass, increasing fuel efficiency and decreasing emissions levels, which costs consumers less money at the pump and benefits the environment. Scientists continually modify polyurethanes to make them even lighter; the density of polyurethane for major applications has been reduced 30%-40% in recent years. Polyurethanes also are tailor-made for each application, reducing scrap material and lowering vehicle costs.
- Space-saving. Scientists are using nanotechnology to reinforce polyurethanes, creating ever-thinner materials that perform as well or better than existing compounds.
- Strength. The power of polyurethane is that it ranges from completely flexible to almost as solid as steel.
- Sound-absorption. Scientists adjust polyurethane chemistry to create headliners, carpet underlays and molded plastic components under the hood that reduce the transmission of road noise. Even the car’s seating materials can be adjusted to improve acoustical performance and help ensure a quieter drive.
Advances in polyurethane chemistry continue to offer new and additional means to reduce vehicle weight while improving performance. And recent developments allow manufacturers to incorporate renewable additives.
“We can now incorporate natural oils into the polyurethane mix, which will help reduce carbon-dioxide emissions,” says Allan James, North American field marketing manager-composite structures for Dow Automotive.
“Containing up to 30% renewable content, new products enable automotive manufacturers to achieve sustainability goals. They also can improve a vehicle’s fuel economy, since the new material is up to 25% lower in density. An added bonus is that these products can also be faster to manufacture, which further reduces the resources needed to produce and operate an automobile.”
The flexibility of polyurethanes also allows for customization, a very important trend in the automobile industry.
“For example, car buyers in the near future will not be limited to the original-equipment manufacturer’s seat specifications. Rather, a very tall or very petite person could choose a seat with a geometry that suits them,” Khalil says.
As automotive technology evolves, polyurethanes will follow suit – just as they have done for the past 50 years.
Lee Salamone is senior director of the Center for the Polyurethanes Industry of the American Chemistry Council. CPI serves as the voice of the polyurethanes industry in North America, promoting its development and coordinating with polyurethane trade associations across the globe. http://polyurethane.americanchemistry.com/
