As landfills overflow with discarded plastics, scientists have been working to produce a biodegradable alternative that will reduce pollution. Now a Tel Aviv University researcher is giving the quest for environmentally friendly plastics an entirely new dimension -- by making them tougher than ever before.
Prof. Moshe Kol of TAU's School of Chemistry is developing a super-strength polypropylene -- one of the world's most commonly used plastics -- that has the potential to replace steel and other materials used in everyday products. This could have a long-term impact on many industries, including car manufacturing, in which plastic parts could replace metallic car parts.
Durable plastics consume less energy during the production process, explains Prof. Kol. And there are additional benefits as well. If polypropylene car parts replaced traditional steel, cars would be lighter overall and consume less fuel, for example. And because the material is cheap, plastic could provide a much more affordable manufacturing alternative.
His research has been published in the journal Angewandte Chemie.
Better building blocks
Although a promising field of research, biodegradable plastics have not yet been able to mimic the durability and resilience of common, non-biodegradable plastics like polypropylene. Prof. Kol believes that the answer could lie in the catalysts, the chemicals that enable their production.
Plastics consist of very long chains called polymers, made of simple building blocks assembled in a repeating pattern. Polymerization catalysts are responsible for connecting these building blocks and create a polymer chain. The better the catalyst, the more orderly and well-defined the chain -- leading to a plastic with a higher melting point and greater strength and durability. This is why the catalyst is a crucial part of the plastic production process.
Prof. Kol and his team of researchers have succeeded in developing a new catalyst for the polypropylene production process, ultimately producing the strongest version of the plastic that has been created to date. "Everyone is using the same building blocks, so the key is to use different machinery," he explains. With their catalyst, the researchers have produced the most accurate or "regular" polypropylene ever made, reaching the highest melting point to date.
Using resources more efficiently
By 2020, the consumption of plastics is estimated to reach 200 million tons a year. Prof. Kol says that because traditional plastics aren't considered green, it's important to think creatively to develop this material, which has become a staple of daily life, with the least amount of harm to the environment. Cheaper and more efficient to produce in terms of energy consumption, as well as non-toxic, Prof. Kol's polypropylene is good news for green manufacturing and could revolutionize the industry. The durability of the plastic results in products that require less maintenance -- and a much longer life for parts made from the plastic.
Beyond car parts, Prof. Kol envisions a number of uses for this and related plastics, including water pipes, which he says could ultimately conserve water use. Drinking water for the home has been traditionally carried by steel and cement pipes. These pipes are susceptible to leakage, leading to waste and therefore higher water bills. But they are also very heavy, so replacing them can be a major, expensive operation.
"Plastic pipes require far fewer raw materials, weighing ten times less than steel and a hundred times less than cement. Reduced leaking means more efficient water use and better water quality," Prof. Kol explains. The replacement of steel water pipes by those made of plastic is becoming more common, and the production of plastics with even greater strength and durability will make this transition even more environmentally-friendly.
Prof. Kol holds the Bruno Landesberg Chair in Green Chemistry at TAU.
- Konstantin Press, Ad Cohen, Israel Goldberg, Vincenzo Venditto, Mina Mazzeo, Moshe Kol. Salalen Titanium Complexes in the Highly Isospecific Polymerization of 1-Hexene and Propylene. Angewandte Chemie International Edition, 2011; 50 (15): 3529 DOI: 10.1002/anie.201007678
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