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Plastic sheets from corn sugar, plastics that degrade in the soil within weeks and plastic-producing trees — the material is all set for a makeover in the next few years.

While we fret about global warming and talk about developing renewable energy, we often gloss over another inconvenient truth: a large amount of our raw material for manufacturing comes from fossil fuel sources. Plastics are the best example of this problem. This ubiquitous material spoils the environment by not degrading for a long time and when it does degrade, it releases carbon dioxide into the atmosphere, thus contributing to global warming. So should we get rid of this material and find replacements? Not really, if some scientists manage to commercialise their work in the next few years.

In the last few years, scientists have made big strides in developing bioplastics as a serious alternative to conventional plastics. They are made from biological sources. Besides, they are more easily degradable, if not biodegradable. Scientists and engineers now think they can provide a bio alternative to some of the most widely used plastic products in the world: shopping bags, cutlery and other moulded products, films for coating and the like. Together they constitute more than one billion tonnes of the material on this planet.

At the University of Alberta in Canada, Professor Suresh Narine now makes polyurethane sheets from Canola. These sheets are usually produced from a petroleum-based substance called polyols. Meanwhile, at the Michigan State University, Ramani Narayan has developed processes to make plastic sheets from starch, and is also developing methods to make polyesters from vegetable oils. Metabolix, a private company in Massachusetts in the US, has pilot plants that make plastics through microbial fermentation. All of them and several other universities and companies are targeting a $250 billion industry.

One way to address the problem posed by plastics is to make them part of the natural carbon cycle. Plastics are now made from petrochemicals, and hence release carbon that went out of the atmosphere a million years ago. “The key issue in making plastics is managing carbon,” says Narayan.

Biodegradability, while perceived as being an important virtue of any product, is not critical if the product is part of the natural carbon cycle. We could degrade products through chemical methods as long as the process does not require the use of energy that will release fossil fuel carbon into the atmosphere. In fact, rapid biodegradability is often an undesirable feature of many manufacturing materials because the product then decays while in use. The term bioplastics does not indicate biodegradability, although bioplastics can be biodegradable under the right conditions. In fact, some petrochemical-based plastics are biodegradable.

At the University of Alberta, Suresh Narine had been working on using vegetable oils — lipids, to be strictly scientific — to develop plastics. In particular, he has now developed a method to make polyurethane plastic sheets from Canola oil. Polyurethane is a class of material that is rubbery or glass-like. It has a wide variety of uses like making rigid and flexible foams, adhesives and many other such products. Narine made polyurethane by passing ozone and then hydrogen under certain conditions and by using some catalysts. “The product is stable and does not degrade while in use,” says Narine, a fourth-generation Indian immigrant from Guyana. His university and a private company, yet unnamed, are building a pilot plant.

Narayan, on the other hand, had made plastics from starch a few years ago, and had set up a start-up based on this technology. He is now developing three kinds of bio-based plastic material: natural polymers from starch and cellulose, moulded products (like plastic spoons and knives) and engineering plastics from vegetable oil. He has developed biodegradable packaging material from different kinds of blending natural products, and some of them have recently found their way to India as Narayan has transferred the technology to an Indian company based in Chennai.

A large number of private companies are now developing commercial bioplastics. Cargill, a company based in Minneapolis in Minnesota, makes plastic sheets from corn sugar. Some companies make synthetic biodegradable plastic as well. BASF, a German chemical company, makes plastics that degrade in the soil within weeks. Yet, one of the most interesting technologies comes from Metabolix, a start-up from Massachusetts Institute of Technology. Metabolix uses microbes to produce plastics, but along with the production of the material, it also generates biofuels. Within five years, this company hopes to develop plants that will produce plastic in their leaves. This will also reduce the cost to a level that is one-fourth of what it is now. That will be a true revolution.

Source: The Telegraph (Kolkata, India)