ADVANCED MATERIALS & PROCESSES | OCTOBER 2024 6 METALS | POLYMERS | CERAMICS POLYMER FOAM SOAKS UP OIL SPILLS Researchers at the University of Waterloo, Canada, developed a polymer material that can absorb more than eight times its weight in oil, offering a new method to clean up spills and accidents. The polymer foam turns into a gel upon contact with oil, thereby preventing groundwater contamination. Applications include use around electric transformers and oil storage facilities that face groundwater leak risks due to accidents or natural disasters such as earthquakes and hurricanes. To determine which material would work best for oil absorption, researchers measured various gel densities and tested their mechanical properties and capacity to hold as much liquid as possible without becoming saturated. Each polymer foam is designed to allow water to pass freely through its porous structure, but triggers a chemical reaction once it comes in contact with oil. The polymer that the team developed features a spongy texture but becomes a semisolid, gel-like substance that seals in oil and prevents leaks. The material is also lightweight and easy to transport. Any oil trapped in the gel can be recovered through a secondary process. The team will now work with industry partner Albarrie Canada to apply their research ADHESIVE-FREE METHOD JOINS WOOD AND METAL Researchers at Graz University of Technology, Austria, achieved an extremely strong bond of wood with both metal and polymer composites by using 3D printing and an ultrasonic joining technique. The team has now successfully tested two methods by which strong joints can be achieved without using adhesives or screws. Applying the new techniques to wood holds promise for the aircraft, automotive, and furniture industries. Beech, oak, carbon fiber-reinforced polyamide and polyphenylene sulfide, 316L stainless steel, and Ti-64 alloys, were used as test materials. With the AddJoining technique, a component made of polymer composite is affixed to and printed directly onto a surface, in this case wood, using 3D printing. The printed material penetrates into the wood pores and causes a chemical reaction, similar to the reaction of glue with wood. The resulting connections were highly successful in mechanical load tests, which were conducted on the untreated wood surface. Even more durable joints could be achieved by introducing a micro- or nano-structure into the wood through laser texturing or etching, which increases the pores and enhances the bonding surfaces. The new technology works especially well with complicated 3D geometries because the components are printed directly onto the surface in whatever geometry is required, say researchers. In ultrasonic joining, highfrequency vibration with low amplitude is applied to the wooden component using a sonotrode. In contact with the base component—in this case, polymer or a polymer composite material—the friction generates heat at the interface, melting the surface of the polymer part. Molten polymer infiltrates the naturally porous wood surface, resulting in a very stable spot joint from a mixture of mechanical interlocking (due to melted plastic solidifying again in the wood) and adhesion forces. Joints could be further strengthened by pretreatment of the wood surface with laser texturing. www.tugraz.at. In ultrasonic joining, wood and the base component are joined by frictional heat. Courtesy of Wolf/TU Graz. Novelis Inc., Atlanta, recently completed its Green Bond financial commitments. Projects include a $2.4 million solar installation in Pieve, Italy, commissioning of a third recycling furnace in Neuss, Germany, and construction of a new recycling plant for beverage cans in Bay Minette, Ala. novelis.com. BRIEF
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