An international team of scientists has developed a new gel formula that helps protect buildings from fire. Tests show that the product is much more effective than currently used products. It is also environmentally friendly and has been approved by the US Forest Service.
The increase in temperature and the extension of the dry season caused by climate change mean that there are significantly more fires breaking out around the world than a dozen or so years ago. This is confirmed, among other things, by research by scientists from June this year, which shows that the number of fires has doubled between 2003 and 2023. Animals and people die in the elements, and fires consume not only vegetation, but also buildings and apartments.
In the face of such a threat, researchers around the world are looking for a solution to protect infrastructure from the devastating power of fire. Recently, a team of scientists from Stanford University and California Polytechnic State University published in the journal “Advanced Materials” the results of research on a new type of fire-resistant gel.
Current preparations work for a short time
Fire protection agents are nothing new these days. Made from super-hygroscopic polymers, they work similarly to the moisture-absorbing powder found in disposable diapers. When mixed with water and sprayed on a building, such an agent swells and turns into a gelatinous substance. When the preparation adheres to the walls and roof, it creates a moist barrier for fire. However, when exposed to high temperatures, it loses its properties.
– Currently used fire protection agents last for about 45 minutes, after which the water evaporates – says Dr. Eric Appel from the Department of Materials Science and Engineering at Stanford University.
The study's co-author said his team managed to create a gel with a different structure, which makes it work much longer.
The effects of climate change PAP
Excellent insulating properties
In the substance designed by Dr. Appel's team, the fire barrier is not only water trapped in the cellulose polymer molecules. The gel also contains silica particles, which play an additional protective role.
– We discovered a unique phenomenon in which a soft, spongy hydrogel changes to a solid form under the influence of high temperature. It then provides improved and long-lasting protection against fires – explains the lead author of the study, an expert in electrochemistry and materials science Changxin Lyla Dong.
When the water evaporates and the cellulose from the biopolymer burns completely, the gel-forming substance is left with silica particles. Its layer has excellent insulating properties, which means it protects the materials covered with it for longer, the scientists explain.
Promising test results
The new substance was tested with flames from a gas burner at a temperature of nearly 1,300 degrees Celsius. The temperature during a forest fire is usually around 500-550 degrees Celsius.
Scientists tried to light several pieces of wood covered with a fireproof gel with a blowtorch. As it turned out, the materials covered with the old composition of preparations ignited after about 90 seconds. Those on which the new gel was applied “resisted” the flames for seven minutes.
– Traditional gels do not work after the water evaporates. Our product, when exposed to fire, creates a silica aerogel that protects the substrate even when the water has completely evaporated – emphasizes Dr. Appel. He assures that the substance is harmless to the environment and people, and its residues can be easily removed.
Climate change and its consequences in the worldAdam Ziemienowicz, Maciej Zieliński/PAP
Accidental discovery
The new gels are based on Dr. Appel’s earlier work on forest fire prevention. In 2019, the researcher used similar materials as a carrier for substances for long-term plant protection. The preparation, sprayed on plants, was intended to prevent the spread of fire in areas where the risk of fires is particularly high.
The researcher admitted that the new discovery was, in a sense, a twist of fate.
“We wondered how these gels would behave on their own, so we simply spread them on a piece of wood and exposed them to a flame from a burner we had in the lab. We saw a super cool effect where the gels swelled up and turned into aerogel foam,” says Dr. Eric Appel.
It took researchers several years to perfect the final form of the gel. The preparation has been approved for use by the US Forest Service, a federal government agency within the United States Department of Agriculture.
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