Although fire windows already exist, they contain a carcinogenic gel, and their production generates a lot of waste. However, a new technology that works in the same basic way is said to be safer and less wasteful. Normally, this kind of window consists of two pieces of glass with a layer of transparent acrylamide-based hydrogel in between.
Once the pane facing the flame is heated to the point of breaking, the gel will be exposed to the flame. When the water in the gel continues to boil, the temperature of the bottom pane will decrease through the evaporative cooling effect. In addition, the gel forms a thick layer of insulating salt on the second layer of glass, further protecting it.
Scientists at the Fraunhofer Institute for Environment, Safety and Energy Technology in Germany, in order to find a more harmless alternative to the toxic acrylamide hydrogel, they conducted experiments with a variety of substances. After about 60 failed attempts, they finally found an undisclosed "basic ingredient" that met the requirements.
It is not carcinogenic and has no other dangers, but it can still keep windows intact when exposed to temperatures exceeding 1000 oC for up to 2 hours. In addition, on a production line that is producing indoor fire doors made of such glass, only 20 kilograms of waste are generated every day. In contrast, according to Fraunhofer’s data, the production of traditional fire windows generates 150 to 160 kilograms of waste per day.
At present, this kind of glass is used in the reconstruction of the Frankfurt Global Tower and the construction of the big tower.