Researchers from Stanford have developed a water-enhancing gel to be sprayed on homes and critical infrastructure to prevent them from burning in wildfires.
The research, published in Advanced materialsshows that the new gels last longer and are significantly more effective than existing commercial gels.
“Under typical wildfire conditions, current hydrohydrating gels dry in 45 minutes,” he said in a statement. Eric Appelassociate professor of materials science and engineering in the College of Engineering, who is the paper’s lead author. “We developed a gel that would have a wider application window (you can spray it further ahead of the fire and still have protection) and would work better when the fire arrives.
Hydrostimulant gels are made from super-absorbent polymers, similar to the absorbent powder found in disposable diapers. When mixed with water and sprayed on a building, they swell into a gel-like substance that adheres to the outside of the structure, creating a thick, wet shield. But conditions near a wildfire are extremely dry: temperatures can be close 100 degreeswith strong winds and zero percent humidity, and even water trapped in a gel evaporates quite quickly.
More durable and improved protection
In the gel designed by Appel and his colleagues, water is just the first layer of protection. In addition to a cellulose-based polymer, the gel contains silica particles that remain when the gels are subjected to heat. “We discovered a unique phenomenon in which a soft, spongy hydrogel seamlessly transforms into a robust aerogel shield under heat, providing enhanced and long-lasting protection against wildfires. This environmentally friendly advance outperforms current commercial solutions, providing a superior and scalable defense against wildfires,” said the study’s lead author, Changxin Dong.
“When water boils and all the cellulose burns off, we end up with silica particles gathered into a foam,” Appel said. “That foam is highly insulating and ends up dispersing all the heat, completely protecting the substrate below.
Silica forms an aerogel, a strong, porous structure that is an excellent insulator. Similar silica aerogels are used in space applications because they are extremely lightweight and can avoid most heat transfer methods.
The researchers tested different formulations of their new gel by applying them to pieces of plywood and exposing them to the direct flame of a gas torch, which burns at a considerably higher temperature than a wildfire. Your most effective formula lasted more than 7 minutes before the plate began to char. When they similarly tested a commercially available water-enhancing gel, it protected the plywood for less than 90 seconds.
“Traditional gels They don’t work once dry“Appel said. “Our materials form this silica aerogel when exposed to fire that continues to protect the treated substrates after all the water has evaporated. These materials can be easily washed once the fire is out.”
Gels that enhance water retention showing formation of heat-activated silica aerogels for protection of critical infrastructure during catastrophic wildfires
