A newly developed adhesive that achieves tack by a magnetic field could lead to serious energy and cost savings for companies that need to put things together on an industrial scale.
In order for the mixture of chemicals in most epoxy-based adhesives to harden or cure, some kind of environmental impact such as heat, light, or moisture must be applied.
Here, this is achieved by a “magneto-curing” process, which is promoted as an option when conventional adhesives are not particularly effective, or in heat-sensitive applications, or when a lot of insulating material is involved (making it tricky to apply heat, light or moisture).
The adhesive works by combining commercial epoxy with tailor-made magnetic nanoparticles that mix manganese, zinc and iron: these nanoparticles heat up when electromagnetic energy passes through them, securing the materials in place.
“Our key development is a way to cure the adhesive within minutes of exposure to a magnetic field, while preventing the surfaces to be applied from overheating,” says materials scientist Terry Steele of Nanyang University of Technology (NTU) in Singapore.
“This is important because some surfaces we want to bond to are extremely sensitive to heat, such as flexible electronics and biodegradable plastics.”
The new adhesive is easier to apply, acts faster and requires less energy and space than conventional mixtures. It does not require a hardener or accelerator and can be adjusted to control the maximum speed and heat temperature as applied.
For example, in the case of carbon fiber products, such as bicycles and helmets, large furnaces are needed to heat the material for many hours for the epoxy adhesive to harden. Unlike this innovative new solution, a small electromagnetic device is required.
In particular, the researchers say that a gram of conventional epoxy adhesive takes an hour in a 2000 W oven to repair. In contrast, a gram of magnetotemir glue takes only 5 minutes in a 200 W electromagnetic device, which appears to be about 120 times less energy to complete the process.
“The curing of our newly developed magneto-adhesive takes only minutes, instead of hours, and yet is able to secure surfaces by bonding high strength, which is of great interest in the sports, medical, automotive and space industries,” say materials scientist Richa Chaudhary.
“This efficient process can also lead to cost savings because the space and energy required for conventional heat curing are significantly reduced.”
The newly designed process eliminates the risk of overheating and uneven heating, and can still achieve high tack of up to 7 megapascals – just like the glue that will start to replace. It took three years to get to this point, and researchers are now looking for commercial partners to collaborate with.
Wood, ceramics and plastics have been tested by this magneto-curing process, which means it is versatile but also very efficient, and there are ways it could potentially improve the speed of modern production lines.
Everything from sports equipment to aerospace components could be combined more efficiently with the new glue, the team says, and the benefits in terms of energy use and carbon emissions could be extremely significant if the material can be grown outside the lab.
“Our temperature-controlled magnetic nanoparticles are designed to mix with existing adhesive formulations in a single pot, so many epoxy-based adhesives on the market could be converted into magnetic field-activated adhesives,” says materials scientist Raju Ramanujan.
The research was published in Applied materials today.