Goodbye, silica. Hello, bamboo. Researchers from China’s Central South University of Forestry and Technology (CSUFT) have developed a transparent material derived from bamboo. While it may seem unusual, it’s not as farfetched as it sounds. Through a delignification process and various techniques, bamboo can become transparent. It can also boast a flame-retardant barrier, reducing heat release, slowing flame spread, and restraining the emission of combustible volatiles, toxic smoke and carbon monoxide.

Researchers have developed a novel flame-retardant, smoke-suppressing, and superhydrophobic transparent bamboo, poised as a promising substitute for silica glass. Photo: Research.

In an analysis posted in the journal Research, the researchers explain that bamboo shares similarities with wood, mainly because it is composed of lignin, cellulose and hemicellulose. Unlike wood, bamboo has a rapid growth and regeneration rate, allowing it to reach maturity and be used as a building material within four to seven years of growth.

Of course, bamboo is not a replacement for silica. Silica continues to be widely used (reaching approximately 130 million tons in 2020) and is highly transparent. However, it has many shortcomings—it’s brittle and dense. It also emits substantial carbon emissions and greenhouse gases during manufacturing.

Those faults have pushed researchers to find replacements, such as wood. Professors Yiqiang Wu and Caichao Wan of CSUFT explain that wood offers high transparency, excellent mechanical strength and superior thermal insulation properties. Wood can be turned into glass by brushing hydrogen peroxide onto thin planks, bleaching out the brown chromophores while leaving the lignin intact. A transparent epoxy is then infused, resulting in a material that allows 90% of visible light to pass through.

The researchers say bamboo has three advantages over traditional silica glass:

  • Its abundance and renewable nature align with environmental sustainability goals;
  • It exhibits high light transmittance and haze, enabling privacy while facilitating the entry of natural light indoors; and
  • It boasts low density and can regulate temperature and humidity, further positioning it as a promising alternative to conventional glass.

Despite bamboo’s benefits, there are challenges. It features impregnated organic polymers, such as epoxy and epoxy-functionalized polymethylmethacrylate, which release substantial heat and toxic smoke during burning, presenting a notable fire hazard and endangering human safety.

To offset the impregnated polymers, the researchers used a vacuum-impregnation technique to introduce an inorganic liquid sodium silicate (Na2O·nSiO2) into the delignified bamboo structure. The researchers also applied a hydrophobic treatment.

“Through this strategy, we can build a three-layered flame-retardant barrier comprising a top silane layer, an intermediate layer of silicon dioxide formed through hydrolysis–condensation of sodium silicate (Na2SiO3) on the surface, and an inner layer of Na2SiO3,” explains Wan. “This strategy achieves a long ignition time of 116 seconds, low total heat release of 0.7 megajoules/square meter (m2), low total smoke production of 0.063 m2, and low peak carbon monoxide concentration of 0.008 kilograms (kg)/kg.”

To achieve transparency in bamboo stems, the researchers explain that they used a delignification process using sodium chlorite, followed by infiltration with a refractive-index-matched filler and liquid sodium silicate, with a refractive index of 1.52. The researchers say that through delignification, the removal of lignin in bamboo, subsequent impregnation with liquid sodium silicate, and surface modification, they have achieved a transparent bamboo with 71.6% optical transmittance and 96.7% haze, making it ideal for uniform indoor lighting and privacy protection.

1 Comment

  1. It seems like this bamboo product would be an alternative for Acrylic or Polycarbonate or other plastic derivatives – more so than glass.

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