Public Release: 

Vietnamese Chemist Finds New Use For Old Cashew Shells

University of Cincinnati

Cincinnati -- A unique research collaboration between the University of Cincinnati and Vietnam could lead to new rubber products improved by the oil squeezed out of old cashew nuts.

Vu-Thi-Yen has been working with Distinguished Research Professor James E. Mark for a little over a year under a National Science Foundation grant to stimulate U.S.-Vietnamese partnerships. Mark is known worldwide for his polymer research and is a member of UC's Polymer Research Center. Vu was working as a research chemist in Hanoi before coming to UC to work on her doctoral degree.

The goal of the research project is to find readily available natural products which can be used to improve the properties of rubber. Vietnam already produces a great deal of latex, the natural ingredient for rubber. Unfortunately, natural rubber doesn't hold up very well in the environment.

"It's easily degraded by sunlight," said Vu. "Natural rubber needs an anti-oxidation agent to prevent it from degrading in sunlight and air."

Fortunately, cashews are also plentiful in Vietnam, and heating cashew shells produces a sticky resin known as cardanol. In her first set of experiments, Vu purified samples of cardanol she brought to UC from Vietnam and blended them with latex to see if the rubber would be more durable.

The idea worked. With assistance from the College of Polymer Engineering at the University of Akron and UC's department of materials science and engineering, she was able to make several samples of blended rubber using cardanol and test their properties. They all turned out to be stronger and longer-lasting than plain latex alone.

The only problem arose when Vu ran out of cardanol samples and had to get more from Vietnam. "When I ran out of samples, I had to request more from a colleague in Ho Chi Minh University, and he had to ship them by mail. He had to do a lot of paperwork."

In addition to cardanol, Vu is also making blends using castor oil, another commonly available ingredient in Vietnam. She says the castor oil is very different chemically from cardanol, so she expects it to have a different effect on the properties of rubber.

Her primary goal is not to make a better tire. She said the ultimate applications of her research will be determined by industry once the properties of the new rubber blends are known. But she expects the benefits of her research to stretch far beyond the University of Cincinnati and Ho Chi Minh University.

"Once we develop applications, we can apply them to industry. Then, other countries may want to use our methods and materials," said Vu.

That would bring a big boost to the economy of Vietnam, but it would also mean long-term environmental benefits. Relying on renewable resources rather than oil-based chemicals is a major advantage. And, no one will have to worry about what to do with all those leftover cashew shells anymore.

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