Thin sheets of compressed fungi have excellent fire-resistant properties and could be used as a non-toxic, biodegradable alternative to current fireproofing materials.
In the past, fireproofing materials were made with toxic, flame-retardant chemicals like asbestos and polybrominated diphenyl ethers (PBDEs). These have been replaced with other flame retardants such as organophosphates, which are considered safer, but some studies have and .
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at RMIT University in Melbourne, Australia, and her colleagues have developed a more eco-friendly fireproofing material using mycelium 鈥� the root-like structure of fungi.
They grew mycelium from edible Basidiomycota fungi in containers of liquid molasses 鈥� a byproduct of sugar-cane refining. They also added sodium hydroxide to convert chitin, a component of the mycelium, into a substance called chitosan.
The mycelium grew as mats on top of the molasses, which the researchers peeled off and dried before pressing them into millimetre-thin sheets.
When they exposed the mycelium sheets to 800掳C flames, the chitosan component quickly formed an outer layer of char that protected the rest of the sheet from burning, says Huynh. 鈥淭he material caught fire for about one second then self-extinguished,鈥� she says.
The sheets only produced water and carbon dioxide when they were ignited, making them safer than existing flame-retardant chemicals, says Huynh. The team now hopes to develop fire-resistant cladding for homes and other buildings out of the fungi, which could be applied as a wallpaper-thin sheet or made into thicker, timber-like panels.
The material appears to be highly durable, says Huynh. Her team previously used it to make bricks, and she says she has had one sitting in her room for 10 years that hasn鈥檛 shown any signs of breaking down. 鈥淚 can still jump on it because it鈥檚 so strong,鈥� she says.
The fungus is killed during the drying process, so there is no danger of mushrooms growing out of the sheets, says Huynh.
However, scaling up production of the material could be challenging. 鈥淭he fungi don鈥檛 need light or electricity to grow, but they do need a big space if you want to grow enough for the building industry,鈥� says Huynh. 鈥淏ecause they鈥檙e biological organisms, they鈥檙e also prone to contamination.鈥�
Huynh says her team has been approached by industry groups that may be able to assist with this scale-up process.
Polymer Degradation and Stability
