A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 1 1 2 MAGNETOCURING ADHESIVE Scientists at Nanyang Technological University, Singapore, invented glue that is activated by a magnetic field. Their “magnetocuring” glue has applications in environmental conditions where current adhesives do not work well. When the adhesive is sandwiched between insulating material like rubber or wood, traditional activators like heat, light, and air cannot easily reach it. The new adhesive is made by combining a commercially available epoxy adhesive with specially tailored magnetic nanoparticles made by the scientists. It does not need to be mixed with any hardener or accelerator, unlike two-component adhesives, making it easy to manufacture and apply. The adhesive bonds the materials when it is activated by passing through a magnetic field, which is easily generated by a small electromagnetic device. This eliminates the need for large industrial ovens to cure the glue, resulting in a smaller manufacturing footprint and less energy consumption. Potential applica- tions include high-end sports equipment, auto- motive products, electronics, energy, aero- space, andmedical manufacturing processes. Laboratory tests have shown that the new adhesive has a strength up to seven megapascals, on par with many of the epoxy adhesives on the market. Moving forward, the team hopes to engage adhesive manufacturers to collaborate on commercializing their technology. They have filed a patent through NTUitive, the university’s innovation and enterprise company. www.ntu.edu.sg. MORE DURABLE TOUCHSCREENS Using a new theoretical model, scientists at the University of Tsukuba, Japan, gained a better understanding of vibrational spread through disordered materials such as glass. They found that as the degree of disorder increased, sound waves traveled less and less like ballistic particles, and instead began diffusing incoherently. This work may lead to new heat- and shatter-resistant glass for smartphones and tablets. Understanding the possible vibrational modes in a material is important for EMERGING TECHNOLOGY The DOE’s Critical Materials Institute, Ames, Iowa, developed a low-cost, high-performance permanent magnet by drawing inspiration from ironnickel alloys found in meteorites. The new magnet rivals widely used alnico magnets in magnetic strength and has the potential to fill a strong demand for magnets that are rare-earth free and cobalt free. ameslab.gov/cmi. BRIEF controlling its optical, thermal, and mechanical properties. The propagation of vibrations in the form of sound of a single frequency through amorphous materials can occur in a unified way, as if it were a particle. However, this approximation can break down if thematerial is too disordered, which limits the ability to predict the strength of glass under a wide range of circumstances. Now, researchers have developed a new theoretical framework that explains the observed vibrations in glass with better agreement with experimental data. They demonstrate that thinking about vibrations as individual phonons is only justified in the limit of long wavelengths. On shorter length scales, disorder leads to increased scattering and the sound waves lose coherence. The equations for low frequencies start looking like those for hydrodynamics, which describe the behavior of fluids. The researchers compared the predictions of the model with data obtained from soda lime glass and showed that they proved a better fit compared with previously accepted equations. “Our research supports the view that this phenomenon is not unique to acoustic phonons, but rather represents a general phenomenon that can occur with other kinds of excitations within disordered materials,” the researchers say. Future work may involve utilizing the effects of disorder to improve the durability of glass for smart devices. www.tsukuba.ac.jp/en. Iron-nickel permanent magnets. Courtesy of DOE Ames Laboratory. From left: NTU faculty, Terry Steele, Raju V. Ramanujan, and Richa Chaudhary holding up various soft and hard materials bonded by their newmagnetocuring glue. Courtesy of NTU Singapore.
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