Glass may soon be replaced by an unlikely rival – bamboo. Scientists in China have turned regular old bamboo into a transparent material that is fire and water resistant and smoke suppressant. Silicate glass, made from sand, is still the right building material when you need something transparent but strong, like windows. But it is not particularly sustainable and can be heavy and fragile.
Transparent wood has been studied for a few years. Scientists chemically remove the lignin from the wood fibers and then process the remaining material. The end result is a material that is transparent, renewable and as strong or stronger than glass, while being lighter and a better thermal insulator. However, there are still some problems with using wood. It is much more flammable than glass and is already in high demand, with stocks taking a long time to replenish. So for the new study, researchers at the Central South University of Forestry and Technology (CSUFT) in China turned to bamboo (“CSUFT Develops Fireproof, Smoke-Resistant Transparent Bamboo“).
Bamboo has a rapid growth and regeneration rate, allowing it to mature and be used as a building material within four to seven years of growth. With a yield four times higher than wood per acre, bamboo is recognized for its outstanding performance.
The internal structure and chemical composition of bamboo is similar to wood, so the team used the same method to make it transparent. After the lignin is removed, the bamboo is sprayed with liquid sodium silicate, which makes it clear. It is then treated to make the material hydrophobic or water repellent.
The end result is a three-layer structure – silane on top, silicon dioxide in the middle and sodium silicate on the bottom. Bamboo is transparent, with 71.6% light transmittance, flame retardant, water repellent and blocks smoke and carbon monoxide. Mechanically, it has a bending modulus of 7.6 GPa and a tensile modulus of 6.7 GPa.
Not only could this transparent bamboo be used as a building material, but when used as a substrate for solar cells, it acted as a light management layer. This increased the power conversion efficiency of the cells by 15.29%. In future research, we will focus on the large-scale fabrication and multi-functionality of this transparent bamboo.
