Remember those abhorrently ugly (and almost certainly orange) laminate countertops in your first apartment? One good bump along the edge and a piece of the laminate would break off from the subsurface — and there went part of your security deposit. Your landlord’s cheapness wasn’t totally responsible for the problem — the layers of the countertop just weren’t well bonded together.
Many materials in our modern world are laminated — that is, they’re composed of multiple layers of materials held together by molecular bonds. Over time and exposure to outside factors, like a hard impact or extreme temperatures, the bonds between layers can weaken in polymers, composites and even steel. The layers can then separate and break, a process called delamination.
When delamination occurs, the material — and anything made from it — can experience catastrophic failure. It’s a huge problem regardless of whether you’re building a steel suspension bridge, a concrete skyscraper, a space shuttle or a bioabsorbable medical device.
So why don’t we do something to strengthen the molecular bonds between layers, you ask? As it turns out, a group of MIT researchers has developed a way to do exactly that. Headed by Dr. Brian Wardle of MIT’s department of aeronautics and astronautics, the NECSTlab has developed a method that uses vertical aligned carbon nanotubes (VACNT) to fill in micron-sized gaps between plies (layers), thereby strengthening the material’s overall structure.
The space between layers “is often where cracks form and propagate in composite laminates,” Dr. Ryan Williams, a senior scientist with N12 Technologies Inc., told Composites World. N12 holds the exclusive license to MIT’s patented VACNT technologies. “We are mitigating crack formation and propagation by putting trillions of carbon nanotubes in the way.”
The technology is called NanoStitch, and researchers are exploring a host of applications for it. In testing, researchers were able to reduce interlaminar shear stress — the forces that cause the separation of layers — by about 30 percent. Check out Composites World’s article “The end of delamination?” for a more detailed and technical explanation of how the technology works.
Delamination has been a chronic problem for as long as humans have been putting layers of materials together to create something new. If NanoStitch technology really can end delamination, it will mean a wealth of products made from composites and polymers will be stronger and more durable. With this advancement, landlords will have to find another reason besides chipped countertops to keep your security deposit!