Material physics: Japanese cutting art inspires super-sticky adhesive tape
An adhesive tape of any kind that adheres strongly and is easy to remove. Researchers developed such an adhesive strip with a pattern inspired by kirigami.
If you pull adhesive tape off a parcel, the cardboard sometimes tears. Not ideal, which is why a team led by Michael Bartlett from Virginia Tech developed an adhesive tape that adheres strongly but can also be easily removed. As the working group wrote in the journal Nature Materials, they modelled their work on the Japanese art of kirigami cutting. The experts cut a scale-like pattern into the adhesive tape, which increased the adhesive strength by a factor of 60. At the same time, the adhesive strip could be removed from a surface in a specific direction.
In Kirigami, a sheet of paper is folded and cut to create a three-dimensional image. Based on this, Bartlett and his colleagues developed a pattern and lasered it onto an adhesive tape. The pattern runs over several lines and consists of rectangular shapes similar to a "U". In other words, the researchers cut three of the four sides of the rectangular shape. If you now pull the adhesive tape in such a way that the sides of the "U" that are not cut are lifted first, the strip comes off. However, it was much more difficult to get the tape off in the other direction.
The researchers describe the physical mechanism behind the process as reverse crack propagation, which is actually known from fracture mechanics. The adhesive tape comes loose as cracks form in the adhesive. However, as soon as you reach the cutting pattern when peeling it off, the forces are concentrated on the narrow strips between the U shapes. There they are finally trapped on the uncut sides of the "U". The result: the direction of the crack propagation is reversed - the adhesive tape adheres even more strongly.
Which type of tape the scientists used was irrelevant for the result - the adhesive force increased each time with the cut pattern, they report. In addition, it would work on surfaces of different materials, under both dry and moist conditions. According to the experts, it was also important that they did not have to change the material or its chemical composition. The cutting pattern alone would have increased the adhesive force by a factor of 60.
For one test, the researchers then sealed one package with their Kirigami adhesive tape and another with normal adhesive tape. They then dropped bricks onto the parcels. The normally taped box collapsed the second time, while the other still held up after the fifth time. "We can take normal parcel tape and reinforce it as necessary," emphasises project team member Chanhong Lee from Virginia Tech according to a press release. "But at the same time, it is possible to detach it. This is very useful for packaging that is also reusable and can play a role in sustainability."
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Cover photo: Alex Parrish / Virginia Tech
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