快猫短视频

BIODEGRADABLE plastic bags made from soya beans would be good for the
environment. They don鈥檛 take up landfill space, and because they degrade quickly
they are less likely to strangle or suffocate wild animals that encounter them.
There is only one problem: the plastic bags are so biodegradable that they
almost dissolve in the rain.

But Joshua Otaigbe, a materials scientist at Iowa State University in Ames,
has found that mixing the soya-bean protein with polyphosphate fillers and
silane produces a more durable and water-resistant plastic.

鈥淭he polyphosphate fillers increase the stiffness and strength of
soya-protein plastic,鈥� he says. 鈥淭hey are also able to reduce the water
absorbency.鈥� The silane retards water absorbency as well, and helps the
polyphosphate to bind with the soya-protein plastic.

In laboratory tests, the modified plastics have survived more than a year
underwater. The unmodified plastic dissolved in a few hours.

Otaigbe is now testing the soya-based plastics in soil to see how well they
degrade. He expects the materials to be useful in a variety of roles, from food
packaging to medical sutures. They may even turn up on the golf course as tees.
鈥淎fter you finish your round of golf you can throw them away to biodegrade in
the environment,鈥� he says.

The plastics will be relatively cheap, Otaigbe says, because soya beans are a
renewable resource. The crop is grown extensively in Iowa and neighbouring
states in the Midwest.