Thursday, May 31, 2007

The Trouble With Tires

Hey, here's a pretty neat advance on the recycling front. Here in Portland, we're big on recycling. We have weekly pickup of our paper, cans, jugs and bottles, scrap metal, cardboard, and most other things that can possibly know a second life. Everywhere you look there are recycling bins next to the trash can, reminding us that with a little extra effort (very little in Portland) we can send these items to be reformed and reused, instead of sending them off to populate a landfill. This community decision is reflective of both the "green" attitude here in Oregon, and the pioneer spirit which led many of our ancestors here, using and reusing our resources, refurbishing and remaking, rather than tossing things that might still have some use left in them. My next door neighbors just built a really great chicken coop (yes, you can have up to three chickens here in the city) entirely out of reclaimed materials. It's quite charming and functional, with sliding doors to unobtrusively get at the eggs, and an old french door, with the glass removed, for an entry. I think one of the things that satisfied them the most, besides the fact it's a really cute addition to their yard, is that they didn't buy a thing to finish the job. It' a fine accomplishment in recycling ingenuity.

Even here in Oregon, however, where recycling is a priority, there's a persistent blight on the "reuse it" record. Some things simply can't be used again, or made into something else with any facility. Chief example? Tires. Tire recycling is a big problem the world over, and many landfills are piled high with the troublesome trash because of the difficulty in finding ways to revive the treated rubber. According to Tom Simonite at, tire rubber, which has been vulcanized--treated with a chemical to make it strong and durable--isn't cooperative in the melting department. Since it won't melt, it can't be merged with new rubber to make new tires, and "retreading" has not been a particularly successful venture. It's just been too difficult to get new rubber to bond to the old tires. So, we're left with piles of tire discards. Haven't we all seen the giant tire graveyards where old tires go when they die? Simonite points out these tires have a tendency to release pollutants and catch fire, and with just the US producing 290 million tires worth of landfill-quality rubber in 2003 alone, it would be in our best interest to come up with some other way to address the problem.

This isn't to say that no one is trying any creative solutions to the tire dilemma. There is some creative tire usage going on. David Isaac, at Swansea University in the UK, says that tires are being ground up for flooring, and I saw a report recently about a fashion designer using bicycle tires for high fashion (seriously ugly, and probably smelly high fashion if you ask me), but, even if wearing tire rubber to the opera were to catch on, these alternatives can barely make a dent in the used tire supply. Wouldn't the best option be to make old tires into new tires, if that were possible? That's something Isaac and his scientist pals have been working on, and they have made some significant progress, using lots of scientific know-how and fancy sciency equipment:

Now, David Isaac and colleagues at Swansea University, UK, have shown that spinning ground-up tyres, called rubber "crumb", inside a chamber filled with ionised oxygen gas plasma could provide a solution.

"It makes the surface of the crumb much better at sticking onto new rubber," Isaac explains. "Without treatment, the interface between the old pieces and new rubber is very weak."

The treated rubber particles can then be added to fresh non-vulcanised rubber to make new tyres. Laboratory tests show that tyre rubber recycled in this way has similar tensile strength and other mechanical properties to completely new material.

Isaac says the plasma treatment appears to create reactive oxygen species - small, highly reactive molecules - on the surface of the rubber by opening up carbon bonds. This reactive surface adheres well to fresh rubber. But it will not stay that way for ever, so the researchers have to add it to new rubber straight away. In the long term, they hope to find a way to make the plasma treatment last longer.

Isn't that nifty? With this technology turning old rubber into new tires that are as strong and durable as the original, there's really no good reason I can see (with my limited understanding of science and economics) that this new approach can't make tire recycling a ubiquitous phenomenon. Now that they've got a workable method, the next step is to sell the technology to the tire manufacturers, and Isaac and crew have formed a company to do just that. Hopefully this method will catch on, making tire fires and tire graveyards a thing of the past. (Oh, and tire "planters" can go bye-bye, too! I know that the people who use old tires that way are being frugal and conservationist and all, but those things are just plain ugly, no matter what color they're painted. I know, I know--I'm being an aesthetics snob again.) Maybe it won't be too long before Bridgestone and Les Schwab are rolling out product lines that actually deplete the supply of used tires in the world. That would make a lot of Oregonians happy, Greens and pioneers alike.