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Corn on the Job: Shri Ramaswamy's research advances our understanding of the interaction of water and corn-based plastics

Office of the Vice President for Research: What goes around, comes around. In the late 1960s polymers were the hot thing. Twenty years later, the material was, well no longer so hot. Plastics were an inexpensive commodity, mostly a world of oil-based resins, pressed, extruded, or blow molded to shape using low-cost, high-speed production techniques.

Now the field has come alive again. For proof, look no further than the 2005 Minnesota State Fair. Hundreds of thousands of people at this year's State Fair picked up that most ubiquitous of giveaways: the plastic carry-bag. Most were of the normal, petroleum-based plastic variety, functional to be sure, perhaps even colorful. But sooner or later, those bags, having done their job, will land unceremoniously in waste bins—and eventually in landfills.

But clogging landfills is not the only possible destiny for some fairgoers' bags. The bags that Shri Ramaswamy and his colleagues at the College gave away had another attribute: They contained plastics derived from agricultural products, and were (and are) biodegradable. They were made with poly lactic acid (PLA), which is one of the biobased polymers recently introduced in the marketplace. "These corn derived plastics essentially degrade within 30 days. So if you have the right conditions—temperature, humidity, and bugs [bacteria], which are typical of industrial compost sites—they go completely back to water and lactic acid and leave no solid waste pollution," Ramaswamy explains.

The use of bio-based PLA plastics in the food industry is growing faster than a Chia Pet soaked in Miracle-Gro. Consumers value "green" plastics for their ecological benefits. With the advancement in technology, and given today's oil prices, bio-based polymers are very cost competitive to conventional petroleum-based polymers. Researchers at the University of Minnesota are working to improve the properties and performance of the bio-based polymers.

Ramaswamy and his colleague, Professor Rich Cairncross from Drexel University, recently received a grant to study one of the problems associated with the type of plastic made from corn-derived PLA. The project is an investigation into the moisture transport and degradation kinetics of PLA products. "I'm working on the use of this plastic in water bottles," says Ramaswamy. "Being bio-based, PLA interacts with moisture and transmits water easily. This is one of the reasons why PLA degrades so quickly and completely. At the same time, ease of transport of moisture through PLA can pose problems in long-term storage and use in applications such as water bottles. The water will evaporate out of the bottle, right through the bottle walls."

Read the full article: http://www.research.umn.edu/spotlight/ramaswamy.html

Learn more about this topic:

Bandyopadhyay, A.; Ramarao, B. V.; Ramaswamy, Shri. Transient moisture diffusion through paperboard materials. Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2002), 206(1-3), 455-467.
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Ramaswamy, S.; Gupta, M.; Goel, A.; Aaltosalmi, U.; Kataja, M.; Koponen, A.; Ramarao, B. V. The 3D structure of fabric and its relationship to liquid and vapor transport. Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2004), 241(1-3), 323-333.
Find It at U of M Libraries

Bandyopadhyay, A.; Ramarao, B. V.; Ramaswamy, Shri. Transient moisture diffusion through paperboard materials. Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2002), 206(1-3), 455-467.
Find It at U of M Libraries

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