Biodegradable reinforced plastics could replace landfills with compost heaps

Instead of landfills clogged with computer and car parts, packaging and a myriad of other plastic parts, a Cornell University fiber scientist has a better idea. In coming years, researcher Anil Netravali says, many of these discarded items will be composted.

The key to this "green" solution, he says, is fully biodegradable composites made from soybean protein and other biodegradable plastics and plant-based fibers.

"These new fully biodegradable, environmentfriendly green composites have good properties and could replace plastic parts in the interiors of cars and trains, in computers and in packaging materials and other consumer products," says Netravali, a professor of fiber science in the College of Human Ecology at Cornell. "They also provide excellent insulation against heat and noise.

Although the plant-based fibers may not be as strong as graphite, for example, they are low in cost, biodegradable and replenishable on a yearly basis," he says.

Instead of nondegradable plastics based on petroleum products, green composites, also known as reinforced plastics, use natural fibers that, for strength, are embedded in a matrix made of a plant- based or other resin. These fibers are obtained from the stem of an Asian perennial shrub and the resin made from a soy protein isolate-polymer.

Netravali notes that most nondegradable plastic composites, made from petroleum-based or synthetic polyurethane, polyethylene and polypropylene, end up in landfills. Not much can be reused or recycled. Plant-based green composites, however, could, he says, become inexpensive alternatives for many massproduced items. "They will be made from yearly renewable agricultural sources and would be environmentally friendly because they would naturally biodegrade once they were thrown on a compost pile."

Netravali's research group is working with a number of fibers including those obtained from kenaf stems, pineapple and henequen leaves and banana stems. The resin materials he is researching include commercial resins, such as polyvinyl alcohol and polylactones, and those derived from microorganisms.

The new composites could also substitute for wood in such applications as crates or building studs.

Netravali agrees that green composites are likely to be more expensive than nonbiodegradable plastics, but as they gain acceptance and the volume increases, they will become less expensive, he says.

For more information, contact Susan Lang,