United States. Researchers at Washington State University have developed an environmentally friendly plant-based material that, for the first time, works better than Styrofoam for insulation.
The foam is mainly made of cellulose nanocrystals, the most abundant plant material on earth. The researchers also developed a simple, environmentally friendly manufacturing process to make the foam, using water as a solvent instead of other harmful solvents.
The work, led by Amir Ameli, an assistant professor in the School of Mechanical and Materials Engineering, and Xiao Zhang, an associate professor in Linda and Linda's School of Chemical and Genetic Engineering, is published in the journal Carbohydrate Polymers.
Researchers have been working to develop an environmentally friendly replacement for Styrofoam. The popular material, made from petroleum, is used in everything from coffee cups to materials for the construction, transportation, and packaging industries. But, it is made of toxic ingredients, depends on oil, does not degrade naturally and creates pollution when burned.
While other researchers have created other cellulose-based foams, the plant-based versions haven't worked as well as Styrofoam. They are not as strong, nor do they isolate, and they degrade at higher temperatures and in humidity. To make cellulose nanocrystals, the researchers use acid hydrolysis, in which acid is used to break chemical bonds.
In their work, the WSU team created a material that is made of about 75 percent cellulose nanocrystals from wood pulp. They added polyvinyl alcohol, another polymer that binds to nanocellulose crystals and makes the resulting foams more elastic. The material they created contains a uniform cellular structure that means it is a good insulator. For the first time, the researchers report, the plant-based material exceeded the insulation capabilities of Styrofoam. It is also very light and can support up to 200 times its weight without changing shape. It degrades well, and burning it does not produce polluting ash.
"We have used an easy method to make high-performance composite foams based on nanocrystalline cellulose with an excellent combination of thermal insulation capacity and mechanical properties," Said Ameli. "Our results demonstrate the potential of renewable materials, such as nanocellulose, for high-performance thermal insulation materials that can contribute to energy savings, reduced use of petroleum-based materials, and reduced adverse environmental impacts."
"This is a fundamental demonstration of the potential of nanocrystalline cellulose as an important industrial material," Zhang said. "This promising material has many desirable properties, and to be able to transfer these properties on a large scale for the first time through this engineering approach is very exciting."
Researchers are now developing formulations for stronger, more durable materials for practical applications. They are interested in incorporating low-cost raw materials to make a commercially viable product and consider how to move from the lab to a real-world manufacturing scale.
The work was supported by the U.S. Department of Agriculture and WSU's Office of Marketing.
Source: Washington State University.
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