Air-filled tires came in 1888 when John Boyd Dunlop wrapped a rubber tube inflated with air around the wheel rims on his son’s tricycle. Too bad he didn’t have this on hand.
It’s one of a driver’s worst nightmares. You hear or feel a pop under your car while driving down the highway. You stop, get out, and inspect, only to see a tire is flat. Great. What now?
If you aren’t in a position to change the tire, or never learned how, there’s a solution: spraying an inflator and sealant into the tire from an aerosol can. The handy product is best known under the brand name Fix-A-Flat. For all its instant gratification, this product is remarkably simple. It uses a liquefied propellant to inflate the tire while a latex emulsion foams to plug the leak.
Although a gas at room temperature, the propellant becomes a liquid when compressed into the can, explains Jiafu Fang, senior product development scientist for Shell Global Solutions, which has owned the Fix-A-Flat brand for close to a decade. When released from the can, the propellant evaporates. The propellant in a 16-oz can is able to expand and fill the whole tire. Fang says gases such as nitrogen and oxygen don’t compress as easily to fit in a convenient 16-oz can.
Currently, flat-fix product makers commonly use the nonflammable refrigerant hydrofluorocarbon (HFC)-134a, whose chemical name is 1,1,1-trifluoroethane, as a propellant. It’s also typically used in car air-conditioning units.
Visit “What’s that Stuff?” to continue reading about Fix-A-Flat.
Excerpted with permission, Chemical & Engineering News
Copyright © 2010 American Chemical Society