Kate Ter Haar/Flickr via Creative Commons

The disposable shopping bag is environmentally problematic. Between 500 billion and 1 trillion plastic bags are consumed each year. They require large amounts of energy and resources to create, and impose hidden costs for the consumer and the environment. The plastic bag has therefore inspired scientists, manufacturers, and designers to create better alternatives. As I wrote previously on ARCHITECT, CycleWood Solutions has developed a disposable "Xylobag" that safely biodegrades in 150 days.

Other strategies address the disposal of existing, non-biodegradable plastic bags. One surprising solution involves the transformation of discarded bags into one of the most sophisticated and rarified of materials: carbon nanotubes. Researchers at the University of Adelaide have recently developed a method for converting conventional plastic bags into carbon nanotube membranes, which are ultra thin films comprised of microscopic cylinders of carbon.

Hundreds of times stronger than steel, yet six times lighter, carbon nanotubes represent one of the most promising emerging materials, with potential applications in biomedicine, energy, and sensing technologies. Research has also been conducted to build everyday products such as computer processors and headphones.

"Non-biodegradable plastic bags are a serious menace to natural ecosystems and present a problem in terms of disposal," said Dusan Losic, a professor at the School of Chemical Engineering, in a University of Adelaide press release. "Transforming these waste materials through 'nanotechnological recycling' provides a potential solution for minimising environmental pollution at the same time as producing high-added value products."

To make the conversion, Losic and fellow scientists heated disposable plastic bags in a furnace, creating polymer vapors that transformed into layers of carbon. They then "grew" the carbon in cylindrical form on membranes of nanoporous alumina. The idea came from Losic's student and doctoral candidate Tariq Altalhi, who argued that any carbon source would suffice for creating the nanotubes.

Although considerable heat and processing energy are required for the conversion, the method produces no toxic waste. Moreover, it enables the remarkable transformation of one of the world's most mundane and troublesome materials into one of its most advanced substances.

Plastic bag photo used with permission via a Creative Commons license with Flickr user katerha.

Blaine Brownell, AIA, is a regularly featured columnist whose stories appear on this website each week. His views and conclusions are not necessarily those of ARCHITECT magazine nor of the American Institute of Architects.