Now plastic from milk protein and clay

BANGALORE - Scientists have reported development of a new ultra-light bio-degradable foam plastic material made from two unlikely ingredients — the protein in milk and ordinary clay.

The American Chemical Society (ACS) said the news comes amid ongoing concern about plastic waste accumulating in municipal landfills causing environmental pollution, and reliance on imported oil to make plastics.

The new lighter-than-a-feather plastic could become a new bio-degradable substitute for Styrofoam - which is a trademark of Dow Chemical Company for polystyrene foam, the ACS said in a press release Wednesday.

David Schiraldi of Case Western Reserve University and co-workers reported the discovery in “Biomacromolecules”, a monthly journal published by the ACS.

The new environment friendly substance could be used in furniture cushions, insulation, packaging and other products, the ACS said.

Schiraldi and colleagues explained that 80 percent of the protein in cow milk is a substance called casein, which finds uses in making adhesives and paper coatings. But casein is not very strong, and water can wash it away.

To strengthen casein and boost its resistance to water, the scientists blended in a small amount of clay (sodium montmorillonite) and a reactive molecule called glyceraldehyde which links caseins protein molecules together.

The scientists freeze-dried the resulting mixture, removing the water to produce a spongy aerogel — a substance very light and airy.

To make the gossamer foam strong, they cured it in an oven and then tested its sturdiness. The researchers found that their spongy material was strong enough for commercial uses. It was bio-degradable with almost a third of the material breaking down within 30 days, the report said.

According to the US Environmental Protection Agency, more than 29 million tons of non-biodegradable plastic waste ends up in landfills each year in the US. Once in the landfill, it does not bio-degrade.

According to ACS, the technology to create bio-degradable plastics from biomass, such as corn and soybeans, has been around for more than 70 years. But plastics made from these sources are expensive.

The ACS said that US scientists at Virginia Polytechnic Institute have also been finding ways to create bio-degradable plastics from agricultural byproducts such as poultry feathers and eggs that would be comparable to petroleum-based plastics. The protein keratin found in feathers is a major component of hair and nails - making them hard and strong.