AsianScientist (Jun. 4, 2020) – Researchers at the University of Science and Technology of China have used cellulose, the most abundant organic molecule on Earth, to develop a strong and light plastic substitute. Their findings have been published in Science Advances.
While plastics are strong, lightweight and inexpensive, plastic waste poses an environmental risk. Broken down by waves, sunlight and marine animals, a single plastic bag can become 1.75 million microscopic fragments that end up in our bodies through the food chain and water supply.
To develop an alternative to plastics, a team led by Professor Yu Shu-Hong has turned to cellulose, the main material in the cell walls of plants. Cellulose nanofibers, which can be derived from plants or bacteria, are stronger than steel and more heat resistant than silica glass, making them in ideal nanoscale building block for constructing high-performance materials, Yu said.
Using the bacteria Gluconacetobacter xylinus, the team first produced cellulose hydrogels that they cut into sheets. After treatment, the sheets were stacked, pressed together and heated until they were completely dry, resulting in cellulose nanofiber plates. These cellulose nanofiber plates were four times stronger than steel and tougher than aluminum alloy, despite being only half its density.
Unlike plastics or other polymer-based materials, the cellulose nanofiber plates were extremely heat resistant, with a thermal expansion coefficient similar to that of ceramic materials. Furthermore, the plates retained their strength despite undergoing ten rapid thermal shocks where they were baked at 120°C and then immersed in -196°C liquid nitrogen.
The researchers reported that the plates could be produced for as little as US$0.50/kg, making them cheaper than—and thus likely to displace—most plastics. In particular, they suggested that the low density, toughness and thermal stability of the cellulose nanofiber plates makes it an attractive and environmentally-friendly engineering material particularly useful for aerospace applications.
The article can be found at: Guan et al. (2020) Lightweight, Tough, and Sustainable Cellulose Nanofiber-derived Bulk Structural Materials With Low Thermal Expansion Coefficient.
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Source: University of Science and Technology of China; Photo: Shutterstock.
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