April 21, 2008 - Biodegradable plastics aren't new, but in the past they've been pretty weak and expensive. Eco-geeks at the Missouri University of Science and Technology have come up with the anti-daywalker of plastic: All of its strengths, but it disintegrates in four months. Another is polylactic acid, which is made by fermenting starches, and breaks down in just 60 days—it's a possible candidate for water bottle plastics.