Microcracks have repeatedly become the cause of plane crashes and serious accidents associated with the destruction of bridges and pipelines. That is why the specialists responsible for the operation of complex engineering objects are faced with the task of detecting them as early as possible.
Experts from the University of Illinois, led by Professors Nancy Sotos and Scott White, have developed a new polymer coating for various materials of construction. Its main feature is the ability to change color in the event of the appearance of the smallest cracks.
The polymer contains epoxy resin microcapsules filled with a light yellow pH-sensitive dye. In the absence of damage, the capsules remain intact. But, as soon as a microcrack appears in the area of the gap, a dye is released, which immediately reacts with the epoxy resin. As a result, a bright red spot appears at the site of damage. The stain increases depending on the size of the crack.
The polymer has already been successfully tested on certain metals, glass and other polymers, the researchers said. The cost of the coating is low, since only 5% of it is microcapsules.
In the future, scientists intend to give the polymer self-healing properties. That is, at the beginning, the polymer, having changed the color, will “inform” about the presence of a crack, and after “curing” it, it will again assume its original color.