2024-08-26 15:52:27
During an experiment with plywood, the researchers demonstrated how the new gel changed from hydrogel to airgel when heated with a gas torch. The torch burns at a higher temperature than would occur in a fire. – ANDREA D’AQUINO
MADRID, 26 years ago. (EUROPE PRESS) –
Stanford researchers have developed a waterproofing gel intended to be sprayed on buildings and critical infrastructure helps prevent them from burning during forest fires.
The study, published in Advanced applicationsshowed that the new gels last longer and are more effective than existing commercial gels.
“Under typical wildfire conditions, current water-enhancing gels dry in 45 minutes,” he said. in a word Eric Appel, associate professor of materials engineering and technology in the College of Engineering, is the lead author of the paper. “We have developed a gel that will contain an extended application window (it can be sprayed further ahead of the fire and still get the benefit of protection) and will work better when the fire arrives.
Absorbent gels are made from highly absorbent polymers, similar to the absorbent material found in disposable diapers. Mixed with water and sprayed on a soil, They swell into a gelatinous substance that adheres to the outside of the system, creating a thick, moist crust.. But the conditions in the area of the forest fire are very dry: Temperatures can approach 100 degrees, with strong winds and zero percent humidity, and even water trapped in a gel evaporates quickly.
In the gel made by Appel and his colleagues, water is the only first level of protection. In addition to the cellulose-based polymer, the gel contains silica particles, which are left after the gels are subjected to heat. “We have discovered a unique phenomenon where a soft, squishy hydrogel seamlessly transforms into a solid airgel shield under heat, offering enhanced and long-lasting protection against severe burns. This eco-friendly achievement goes beyond current business solutionsthat offers superior and scalable protection against large fires,” said the author of the study, Changxin Dong.
“When the water boils and all the cellulose dissolves, we’re left with silica particles that gather in the foam,” Appel said. “This form is very insulating and ends up dissipating all the heat, completely protecting the substrate under it. “
Silica forms an airgel, a strong, porous base that is an excellent insulator. Similar silica aerogels are used in space applications because they are very light and They can avoid many heat transfer methods.
The researchers tested several formulations of their new gel by placing them on pieces of plywood and exposing them to the direct flame of a gas torch, which burns at a much higher temperature than a forest fire. The most effective process lasts longer than 7 minutes before the plate starts to charge. When they tested a commercially available waterproofing gel in the same way, it protected the plywood for less than 90 seconds.
“Traditional gels don’t work once they dry out,” Appel said. “Our materials form this silica airgel when exposed to light that continues to protect treated substrates after all the water has dried. These materials can be washed easily once the fire is out. “
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