Kirigami, the ancient Japanese art of paper cutting, has been adapted by researchers at Virginia Tech to make duct tape much stronger yet easier to remove than today's super tape.
From quickly securing household items to securing a safe seal on mailing packaging, it's helpful to have tape with a strong bond, but it can only be removed by cutting, as is the case with cardboard boxes, or by scraping, and you can be sure that pieces of it will stay on surface.
Professor Michael Bartlett's university group succeeded in significantly increasing the adhesive bond, that is, the sticky property, as well as making the substance easy to remove.
“This seemingly paradoxical combination of properties could revolutionize the application of robotic gripper, wearable health monitoring devices, and production to assembly and recycling,” Professor Bartlett explained.
Easy-to-remove masking tape was first developed in the 1920s to meet the needs of car painters who needed better options for two-tone car paint. Since then, factories have produced invisible tape for wrapping gifts, insulating tape for covering wires, and duct tape for more uses.
“Typically, when the tapes come off, they separate in a straight line along the entire length of the strip until the tape is completely removed. Strong adhesives are more difficult to peel off, while reusable adhesives promote strength-limiting separation.”
Bartlett, inspired by kirigami tried to control a "splitting path" in which folding and cutting to transform a flat sheet of paper is used, a technique children use when making paper snowflakes.
They made a series of U-shaped cuts on the adhesive backing and found that these cuts increased the adhesion of the tape by 60 times.
“The engineered cut can cause the adhesive's separation path to go backwards in certain places, which we call crack backpropagation, which makes the adhesive very strong. But when peeling in the opposite direction, it always goes forward, which makes it easier to remove.”
This is a rather unusual behavior, but very useful for making strong but easily detachable tapes.
The team also reported with a published study in Nature Materials that the type of tape doesn't matter. Kirigami has increased the grip of all the tapes tested, from packaging to medical. In all cases, adhesive bonds become much stronger.
“What really matters is the shape and size of the incision,” the engineers say. "We don't have to rely on a specific adhesive, but because the notches are made to a characteristic size that is determined by the physical properties of the adhesive, we've found this increases adhesion in every system we've tried."
“We're also taking a rapid digital manufacturing approach so we can quickly create highly customizable adhesives with adjustable strength,” Bartlett said. “This is very exciting for developing the adhesives of the future.”
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