Rice and egg whites transform wood into a translucent window alternative

The windows and smartphone screens can one day be built from clear wood mixed with egg whites and may be safely composted at the end of life.

Researchers are interested in using wood to make biodegradable alternatives to glass with better insulating properties or replacing plastics with electronic devices. Wood was previously transformed into a transparent material by altering or removing organic polymer lignin from it and injecting epoxy as a replacement, which produces a non-biodegradable product.

now Bharat Baruah Kennesaw State University in Georgia and his colleagues have developed a process of replacing synthetic epoxy with natural egg whites and rice extracts.

“[Previous examples of transparent wood are] It’s very difficult to integrate, it’s difficult to make, and you spend a lot of time, energy and money making them, so we thought of making something that can be easily made naturally,” says Barua.

He was urged to use egg whites in his home building in Assam, India, which dates back to the 1500s, using a cement-like mixture containing sand, sticky rice and egg whites. “It was cement from the time and those buildings are still there,” Barua says. “They are still there, over the fourth century and beyond, and after the fifth century, but that has always been fascinating to me.”

The team ingested a sheet of balsa wood, soaked sodium sulfate, sodium hydroxide, and diluted bleach in a vacuum chamber, removing lignin and hemicellulose, leaving only a paper-like cellulose structure. The voids of the ingredients were then filled with a mixture of rice extract and egg whites and then dried in an oven at 60°C (140°F) to create a translucent plate with a slight brown tint. “It’s not 100% transparent, but it’s translucent,” says Barua. “And it’s biodegradable.”

Barua and his colleagues built a small birdhouse equipped with clear wooden windows as a basic mockup, and found to remain cool at 5-6°C (9-11°F) when exposed to heat lamps than the same birdhouse equipped with glass windows. The study will be presented today at the American Chemical Society’s Spring Conference in San Diego, California.

Barua said further research will investigate technologies to improve the strength and thermal properties of the material, as well as transparency.