Chemistry: Matter and ChangeChapter 23: Substituted Hydrocarbons and Their ReactionIn the NewsQuiet RiceFebruary 2005One of the neatest things about science is the fact that you never know what you're going to discover next. This is obviously true for archaeologists who are sifting through the remnants of a lost civilization, or for marine biologists who take a mini-submarine down to the deep sea. What you may not realize, though, is that it's just as true for chemists working in labs. Here's a great example of a scientific surprise: Chemistry and Industry Magazine reported this year that Japanese chemists have developed a new material that can be used to make better roads. This new material is highly durable, which of course good roads have to be, as well as resistant to friction. It may improve the way roads are constructed all across Japan. How have these chemists produced this impressive new material? By experimenting with a substance that isn't new at all . . . rice. The Secret Ingredient Yep--rice. In an age of super-polymers, the Japanese team decided to try working with good old fashioned rice bran. The “bran” is a brownish part of the rice plant the comes between the grains and the husks. Rice bran is what's known as a “waste product.” That means it's usually just thrown away, or at best fed to cattle. It's an easy substance to come by. When mixed with resin and asphalt, though, everyday rice bran was found by these chemists to form a new material with many interesting properties . . . such as the ability to make a hard, smooth driving surface. Who would have thought that? More Rice, Less Noise That's not all the chemists found: rice bran-based surfaces were discovered to have other properties that are equally useful. One is that water runs off them nicely, which is a good thing if you want a material that can sit outside in the rain all day without going soggy. Another is that they are resistant to temperature change, which is a good thing if you want a material that can sit outside in the sun all day without cracking. Best of all, though, rice bran-based surfaces absorb sound efficiently--in fact, up to 25% more efficiently than roads made just of asphalt. This ability to absorb sound waves is no small issue, especially when you consider how many congested urban area there are in Japan. Chemists have been working for some time on trying to come up with less noisy roads. Now, that may sound funny. After all, roads don't make noise, cars do. Right? Well, yes and no. Passing cars send out pressure waves--noise--but roads reflect those waves, which has the effect of getting more of them to your ear. It's like saying “Mirrors don't produce light, candles do.” That's true, but a room with mirrored walls will be brighter than one with black walls, because more of the ambient light will be bounced toward your eyes. Chemists have in the past tried mixing different things, such as glass filaments, with asphalt in order to increase its sound-absorbing properties. Some mixtures work better than others. Now, it seems, rice bran roads may be the best of all. Coming Soon to a Road Near You Of course, a more noise-absorbent road is a good thing anywhere. America isn't exactly known for its quiet cities, either. So don't be surprised if some day soon when you visit New York or Chicago or Los Angeles, that smooth, dry, quiet ride you take is the result of rolling on rice . . . and some clever chemistry. Activity: Try walking around the house in different shoes. What kind make the most noise? What make the least? Can you change the amount of noise you make by staying away from certain surfaces? See if you can come up with a way to walk completely through the house without making any noise at all, simply by paying attention to where you step and what's on your feet. Science Daily: The Society of Chemical Industry: Living on Earth: |  |
