24 April 2008

Environmentally friendly plastics plan

One of the greatest marketing moves ever, bottled water, adds more than 30 billion water bottles to America’s landfills, creating a mountainous environmental problem.

However, there is now a plan afoot to create a type of plastic that can dissipate within four months.

New breeds of biodegradable and bioavailable plastics are in the design stage in an effort to reduce the tons of plastic waste that end up in the nation’s landfills each year, according to a research team from Missouri University of Science and Technology led by Dr. K.B. Lee, professor of chemical engineering. Bioavailable plastics contain substances that living systems can absorb during their normal physiological functions.

By combining and modifying a variety of bio-based, oil-based, and natural polymers, the team wants to create optimal blends that can make agricultural films, bottles, biomedical and drug delivery devices, and more.

Although companies already sell biodegradable polymers, the products are often expensive, of poor quality, or developed for specific applications. That is why the team is investigating how they can add in bio-based fillers, such as starch and fibers, to reduce the cost in a variety of commercial applications.

The group is also interested in incorporating glycerol—a major byproduct of the biodiesel process—in the new plastics.

Some of the group’s new polymers incorporate renewable resources, such as polylactic acid, which results from fermented starch. The group’s interest level in renewable resources results from their research and development efforts on developing efficient and cost-effective biodiesel and corn ethanol processes.

“Different chemical and biological mechanisms are responsible for the degradation of polymers,” said Mahin Shahlari, a chemical engineering Ph.D. student at Missouri S&T. “For example, it’s known that polylactic acid will degrade in 45 to 60 days if composted at temperatures between 122 to 140 degrees Fahrenheit.”

As polylactic acid degrades, the material reacts with water to decompose into small molecules, which then mineralize into water and carbon dioxide.

“In general, the main end products of polymer degradation are water and carbon dioxide,” Shahlari said. “Polylactic acid has the potential of replacing the regular water bottles, and we anticipate that our research could be incorporated into that field too.

“We are not just molding and extruding commercially available biodegrable resins. We also are incorporating nanotechnology, supercritical fluid technology, and graft copolymer compatibilization, most of which are developed and patented by our group.”

For related information, go to www.isa.org/environment.