Environment Clean Generations: plastics

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Food-based Plastics A Good Idea?

Once upon a time, food was used for one thing: eating. Today, it has a much more complicated role; scientists, manufacturers and policy makers are exploring whether food could one day eliminate our dependence on oil. Food-based fuels like ethanol and biodiesel are increasingly replacing gasoline and diesel in our fuel tanks. Now, some think food can do the same thing to the plastics industry, helping to replace more than 900,000 barrels of oil and natural gas used to manufacture plastic in the United States daily [source: U.S. EIA].

Food-based plastics, made out of everything from corn to sugarcane, have rapidly grown in popularity over the past several years. Packaging materials, gift cards, cell phone casings -- all can be made from these eco-friendly materials. As the quality of food-based plastics improves, they will have broader and broader applications.

Proponents cite two main advantages of food-based plastics over their petroleum-based counterparts. First, they're made from a renewable resource. As long as farmers grow the crops these plastics are made out of, production can continue indefinitely. Second, food-based plastics are widely considered to be easier on the environment. For instance, they require much less energy to produce than traditional plastics and release fewer greenhouse gases in the process. Better yet, they break down into harmless organic compounds -- in the right conditions.

Now for the drawbacks. One of the most glaring is their relatively low melting point. While popular plastics like polyethylene terephthalate (PET) may have melting points well beyond 400 degrees Fahrenheit (204 degrees Celsius), some plant-based plastics turn into puddles just from being left in a car on a sunny day [source: Machinist Materials]. For instance, polylactic acid (PLA), a corn-based plastic used by retail giant Wal-Mart among other companies, can have a melting point of just 114 degrees Fahrenheit (46 degrees Celsius) [source: Royte]. As a result, food-based plastics are simply unsuitable for a wide range of applications.

What's more, food-based plastics may not be as environmentally friendly as they appear. While they are biodegradable, most only break down under very specific conditions found in industrial composting plants. That means you can't simply throw them on the compost pile in your backyard and expect them to turn into soil, and if they do end up in a landfill, they break down just as slowly as conventional plastics.

While food-based plastics can be recycled, they can't simply be mixed in with other recyclable plastics. In fact, the recycling industry considers food-based plastics a "contaminant" that takes time and money to process.

A final argument against food-based plastics is that generating them requires land and resources that could be going to producing actual food. Already, the U.S. Department of Agriculture (USDA) estimates that, by 2014, nearly a quarter of all grain production will go toward making ethanol and other biofuels; if food-based plastics take off, that number could climb even higher [source: Baker and Zahniser]. Environmentalists also worry about the harmful effects of the pesticides and genetically modified crop strains used to create some of these plastics.

But don't give up on food-based plastics yet. While they still represent less than 1 percent of the plastics market, some very large companies have committed to both improving and using the plastics moving forward [source: Environmental Leader].

For instance, electronics manufacturers Panasonic and NEC have both announced the development of food-based plastics with significantly improved durability, heat resistance and ease of production compared to products currently on the market. Metabolix, another bioplastics manufacturer, has developed a plastic called Mirel that biodegrades in normal compost piles.

Production costs for food-based plastics are rapidly dropping as well, which, coupled with their widening range of applications, will make them a much stronger alternative to conventional plastics moving forward. Perhaps the strongest argument for food-based plastics, however, is that after we've finally exhausted our supply of oil, they'll still be waiting for us.

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Posted in: contaminant,environment,Food-based Plastics A Good Idea?,gasoline,landfill,materials,plastics

Plastic Ocean

The most plastic at the surface of the western Atlantic centers off of Atlanta and stretches from Virginia to Cuba. The number of plastic pieces in that area has not changed in more than 20 years. It's a mystery where all our extra plastic is going, raising concerns for the environment and health.

The concentration of plastic bits floating on the surface of the Atlantic has held steady for more than 20 years, found a new study, even as people use and discard ever-increasing amounts of plastic.

With growing concerns about plastic in the environment, the surprising new finding raises questions about where all that stuff is ending up.

“We know that the global production of plastic has increased at a very high rate, and we know that plastics in the waste stream have also increased over time,” said Kara Lavender, an oceanographer at the Sea Education Association in Woods Hole, Mass.

“We infer that plastic in the ocean is most likely increasing,” she added. “So how come we’re not seeing increasing amounts of plastic in areas where the plastic is accumulating? That’s the mystery.”

Although massive garbage patches have drawn lots of attention lately to plastic in the oceans, few studies have looked at exactly how much is out there and where it’s going. Lavender realized she had the perfect data set just waiting to be analyzed.

For nearly 40 years, the Sea Education Association (SEA) has been taking college students on educational semesters at sea. As part of the program, students have sampled surface waters by dragging a one meter-wide mesh net behind their live-aboard ship.

The net, which catches anything bigger than one-third of a millimeter wide, has been dragged throughout the western Atlantic, from Newfoundland to the southern Caribbean. When it comes back onboard after sampling a nautical mile, SEA students use tweezers to pick through the plankton, jellies, tiny fish and occasional tar balls.

Within the gooey brown mush, they count and record every single piece of plastic. For the new study, Lavender and colleagues compiled 22 years' worth of those numbers.

One of the work’s major findings, published this week in the journal Science, was to show for the first time that the highest concentration of plastic in the western Atlantic is centered in a region offshore at about the latitude of Atlanta. The bulk of the waste stretches from Virginia to Cuba.

To the surprise of Lavender and her colleagues, the study also showed no overall change in the amount of plastic snared from 1986 to 2008, even though they assume more plastic is making its way into the ocean.

“I expected to see the line go right up,” she said. “It took us a good year to decide, no, we have not seen an increase, no matter how you slice it.”

Where is all the missing plastic?

One theory is that it’s breaking down into really tiny pieces that the nets can’t catch. Another possibility is that it’s sinking below the surface, either because tiny organisms are growing on it and weighing it down, or because birds, fish and other animals are eating it and excreting it.

Or maybe the plastic is getting incorporated into tissues of animals that mistake it for food.

Each scenario offers consequences to be concerned about. When animals eat plastic, they can damage their insides, become malnourished, or consume chemical pollutants, which tend to stick to plastic like a sponge. These pollutants may then work their way through the food chain all the way up to people.

When drifting plastic becomes homes for colonizing organisms like barnacles, they can become vehicles for invasive species, added University of Hawaii oceanographer David Karl, whose recent work has shown that plastic is like the bottom of a boat -- an easy target for ocean slime.

Degenerating plastics also release chemicals with unknown consequences.

“Plastic is a chemical compound that does not naturally occur in nature,” Lavender said. “We could be altering the chemistry of the ocean.”

Of course, the findings could also be good news, Karl said. Maybe the plastic is simply washing back up onto shore. Or maybe people are being more careful with trash disposal and recycling, and less plastic is getting into the ocean, though he admitted that was a hard scenario to believe.

“This may be another unplanned experiment of humankind,” Karl said. “Since the 1950s, we’ve been putting plastic into the ocean. Now we’re trying to figure out where it’s gone and what it’s done and what the impact is ecologically.”

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Posted in: ocean,plastics,production

Biodegradable Styrofoam

    Scientists have developed a Styrofoam-plastic out of mostly clay and milk proteins. The material is lightweight, sturdy and largely biodegradable. Before the material can go mainstream, researchers need to overcome practical and technological hurdles.

              We already have plastics made from corn and sugar. Now, scientists have created a Styrofoam-like material using mostly milk proteins and clay.
Ultra-light and largely biodegradable, the plastic might some day become a green alternative to petroleum-derived foam packaging blocks, among other applications.

              "The idea that we could go from milk and dirt to plastic foam seems attractive," said David Schiraldi, a polymer scientist at Case Western Reserve University in Cleveland. "Clay is pretty close to inexhaustible. Our only effluent is water vapor. It seems pretty green to me."
The research began with an accidental discovery in the lab. One of Schiraldi's students freeze-dried clay and got something intriguing enough to warrant a closer look. So, the team started mixing the clay with a variety of materials.
When they added a cow's milk protein called casein, they ended up with a super-light, fluffy, and foam-like material. With further experimentation, they hit on a recipe that worked well enough for publication in the journal Biomacromolecules.

"The process," Schiraldi said, "is simplicity itself."
The researchers start by throwing a scoop of clay and some water into a kitchen blender. Two minutes of mixing produces what Schiraldi's students call a clay smoothie.
Next, they add some casein powder, a dried version of the most common protein in milk. The final ingredient is a tiny amount of a glycerol-based material, which basically stiffens up the solution's chemical bonds.
After running the blender one last time, the scientists pour the dirty-looking water into molds and freeze them like ice-cubes. Then, they freeze-dry it get all the water out.

                The result, Schiraldi said, is a material that has all the same properties of Styrofoam, but is 98 percent bio-based. At 100 degrees Celsius (212 degrees Fahrenheit), the milk-containing foam lets out a few drops of water. But it stays sturdy up to 200 degrees Celsius (392 degrees Fahrenheit).

                In tests conducted by the U.S. Department of Agriculture, close to a third of the new material broke down after about 45 days in industrial compost conditions. That's a huge environmental leap beyond Styrofoam and other types of Expanded Polystyrene Foam, a category of materials that is often used as disposable packaging for electronics and other products.
"Compared to expanded polystyrene foam, we're in a different league," Schiraldi said. "Styrofoam lives forever."

                The research spawned a brand new start-up company called Aeroclay, Inc., which is using the patented technology to develop practical products. Schiraldi imagines a plastic factory of the future that taps into vats of milk instead of oil.
                Before milk-based plastics will go mainstream, though, there are technological hurdles to overcome. For example, scientists will need to make sure that the new material doesn't smell like sour milk.
There are also practical market pressures to contend with, said James McGrath, a chemical engineer at Virginia Tech in Blacksburg.
                "It makes a nice quote to say this is going to replace polystyrene foam, but there are a lot of issues," McGrath said, "including economic ones and the price-to-volume relationship."
               "It always looks good to come up with something like this," he added. "It's a very worthwhile objective to pursue."

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Posted in: biodegradable,environment,plastics,styrofoam

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