New type of glass inspired by nature is more…

New type of glass inspired by nature is more resistant to impacts

Using the iridescent mother-of-pearl often found lining seashells, researchers have engineered a new composite glass with a greatly boosted resistance to impacts.

Glass’s transparency and durability make it the material of choice in countless applications. But whether it’s used “in a car, a building or a smartphone, glass components are always the weakest links and the most fragile in the entire system,” said Francois Barthelat, a mechanical engineer at McGill University in Montreal who devised the new glass with his colleagues. Under stress, the inherently brittle nature of glass means that preexisting flaws within it can spread, triggering sudden catastrophic failure.

Strategies to make glass more impact-resistant include lamination, which bonds two or more glass plates together with thin layers of resin or other polymers in between, and tempering, which toughens glass through reheating and rapid cooling. However, Barthelat and his colleagues think they can do better by looking to nature for inspiration.

For the past 15 years, they have focused on the structure and mechanics of mother-of-pearl, an opalescent impact-resistant material, also known as nacre, that helps shield the soft bodies of mollusks from strong predator jaws. “Animals take relatively weak ingredients—a brittle mineral, soft proteins—and turn them into a hard yet extremely tough armor,” Barthelat said.

Read more.

Digitally programmable perovskite nanowire-b…

Digitally programmable perovskite nanowire-block copolymer composites

One-dimensional nanomaterials with highly anisotropic optoelectronic properties can be used within energy harvesting applications, flexible electronics and biomedical imaging devices. In materials science and nanotechnology, 3-D patterning methods can be used to precisely assemble nanowires with locally controlled composition and orientation to allow new optoelectronic device designs. In a recent report, Nanjia Zhou and an interdisciplinary research team at the Harvard University, Wyss Institute of Biologically Inspired Engineering, Lawrence Berkeley National Laboratory and the Kavli Energy Nanoscience Institute developed and 3-D printed nanocomposite inks composed of brightly emitting colloidal cesium lead halide perovskite (CsPbX3, where X= Cl, Br, or I) nanowires.

They suspended the bright nanowires in a polystyrene-polyisoprene-polystyrene block copolymer matrix and defined the nanowire alignment using a programmed print path. The scientist produced optical nanocomposites that exhibited highly polarized absorption and emission properties. To highlight the versatility of the technique they produced several devices, including optical storage, encryption, sensing and full color displays. The work is now published on Science Advances.

Read more.

Nature-inspired materials can be used in app…

Nature-inspired materials can be used in applications ranging from tunneling to space

Optimal materials for cutting tools of tunnel boring machines (TBM) were developed in the recently finished three-year long project “Innovative polycrystalline diamond (PDC) drag bit for soft ground tunnel boring machines” by TalTech materials scientists from the tribology and recycling group.

The history of tunnel boring machines can be traced back to 200 years ago when the first tunnels were built. In general, the materialsof a TBM that are in contact with abrasive particles can be divided into metals, ceramics and materials that combine them, i.e. composites. The composites usually have the highest wear resistance in aggressive environments. “We were trying to improve the wear resistance of materials of moving elements of a TBM and the composites were the right choice for further development,” the head of tribology and recycling research group, senior researcher of TalTech School of Engineering, Maksim Antonov explains.

The tests done during the research period were following the main goal—to prolong the lifetime of TBM cutting tools in order to minimize the need for their replacement. The tools made of materials with higher wear resistance can be replaced less frequently.

Read more.

Electron beam strengthens recyclable nanocom…

Electron beam strengthens recyclable nanocomposite

Polymers reinforced with carbon fibers combine strength and low weight. They also boast significant green credentials as they are less resource-intensive during production and use, and they are readily recycled. While the mechanical properties of continuous-fiber laminates are sufficiently competitive for applications in aerospace and automobiles, composites reinforced with short carbon fibers could be attractive for fast-manufacture, and even 3-D printing for applications with more moderate strength requirements. As a result, there is keen interest in optimizing the mechanical properties of short-fiber reinforced thermoplastics to maximize on the potential of these materials. László Szabó and Kenji Takahashi and colleagues at Kanazawa University and Kanazawa Institute of Technology have now demonstrated that irradiating short carbon fiber thermoplastics with an electron beam can improve their mechanical properties.

The researchers limited their study to polymers that so that the resulting composite could be readily recycled and remolded into other forms. With environmentally friendly concerns in mind they focused the study on the biobased cellulose propionate for the composite matrix. Their study included investigation of the effects of electron beamirradiation on the strength for polymers functionalized with esters to increase crosslinking, and enhanced with carbon fibers, as well as different forms during irradiation (dumbbells and pellets) and long and short extrusion nozzles.

Read more.

Bioinspired Materials—Graphene-enabled nicke…

Bioinspired Materials—Graphene-enabled nickel composites

Bioinspired engineering strategies rely on achieving the combined biological properties of strength and toughness inherent in nature. Tissue engineers and materials scientists therefore aim to construct intelligent, hierarchical biomimetic structures from limited resources. As a representative material, natural nacremaintains a brick-and-mortar structure that allows many viable toughening mechanisms on multiple scales. Such naturally occurring materials demonstrate an outstanding combination of strength and toughness, unlike any synthetic, engineered biomaterial.

In a recent study, Yunya Zhang and co-workers at the departments of Mechanical and Aerospace Engineering, Materials Science and Atom-Probe Tomography in the U.S. developed a bioinspired Ni/Ni3C composite to mimic nacre-like brick-and-mortar structure with Ni powders and graphene sheets. They showed that the composite achieved 73 percent increase in strength with only a 28 percent compromise in ductility to indicate a notable improvement in toughness.

In the study, the researchers developed optimized material of graphene-derived, nickel- (Ni), titanium- (Ti) and aluminum- (Al) based composites (Ni-Ti-Al/ Ni3C composite) that retained high hardness of up to 1000 °C. The materials scientistsunveiled a new method in the work to fabricate smart 2-D materials and engineer high-performance metal matrix composites. The composites displayed a brick-and-mortar structure via interfacial reactions to develop functionally advanced Ni-C based alloys for high-temperature environments. The results are now published in Science Advances.

Read more.

Scientists create new aluminum alloy with fl…

Scientists create new aluminum alloy with flexibility, strength, lightness

Aluminum is one of the most promising materials for aeronautics and automobile industry. Scientists from the National University of Science and Technology (MISIS) found a simple and efficient way of strengthening aluminum-based composite materials. Doping aluminum melt with nickel and lanthanum, scientists managed to create a material combining benefits of both composite materials and standard alloys: flexibility, strength, lightness. The article on the research is published in Materials Letters.

Lighter and faster aircraft and vehicles require lighter materials. One of the most promising materials is aluminum, or rather, aluminum-based composites.

Scientists from NUST MISIS scientific school “Phase Transitions and Development of Non-Ferrous Alloys” created a new strong Al-Ni-La composite for aircraft and automobile industry. Doping elements were added to the aluminum melt, forming special chemical compounds that further formed strong reinforcing structure.

Read more.

Researchers create soft, flexible materials …

Researchers create soft, flexible materials with enhanced properties

A team of polymer chemists and engineers from Carnegie Mellon University have developed a new methodology that can be used to create a class of stretchable polymer composites with enhanced electrical and thermal properties. These materials are promising candidates for use in soft robotics, self-healing electronics and medical devices. The results are published in the May 20 issue of Nature Nanotechnology.

In the study, the researchers combined their expertise in foundational science and engineering to devise a method that uniformly incorporates eutectic gallium indium (EGaIn), a metal alloy that is liquid at ambient temperatures, into an elastomer. This created a new material—a highly stretchable, soft, multi-functional composite that has a high level of thermal stability and electrical conductivity.

Carmel Majidi, a professor of Mechanical Engineering at Carnegie Mellon and director of the Soft Machines Lab, has conducted extensive research into developing new, soft materials that can be used for biomedical and other applications. As part of this research, he developed rubber composites seeded with nanoscopic droplets of liquid metal. The materials seemed to be promising, but the mechanical mixing technique he used to combine the components yielded materials with inconsistent compositions, and as a result, inconsistent properties.

Read more.

Regular

Predicting properties of composite materials

Ali Gooneie simulates on his computer what holds the world together right at its very core: atoms, molecules, molecular chains and bundles – then lumps and fibers, which emerge thereof. With his calculations, the Empa researcher can also explain properties we can feel with our fingertips: smooth and rough surfaces, flexible and rigid materials, heat-conductive substances and insulators.

Many of these properties have their origin deep inside the materials. Metal or wood, plastic or ceramics, stone or gel – all of these have been examined many times before. However, what about composite materials? How do the properties of such materials come about and how can they be altered in a desired way? A tedious trial-and-error approach in the lab is no longer sufficient in today’s fast-paced research; nowadays, you need computer-assisted predictions to be able to decide quickly which experimental path you will have to take.

Gooneie is one of many computer simulation experts who work in various research labs at Empa. He studied polymer technology at Amirkabir University of Technology in Tehran and did his doctorate at the University of Leoben in Austria. “Although after my engineering degree I immersed myself ever deeper in the world of physics formulae, I never lost touch with the real world,” he says. “For me, simulations are not an end in themselves. I use them to explain the effects we observe in materials.”

Read more.

New way to beat the heat in electronics: Rice …

New way to beat the heat in electronics: Rice University lab’s flexible insulator offers high strength and superior thermal conduction

A nanocomposite invented at Rice University’s Brown School of Engineering promises to be a superior high-temperature dielectric material for flexible electronics, energy storage and electric devices. A lab video shows how quickly heat disperses from a composite of a polymer nanoscale fiber layer and boron nitride nanosheets. When exposed to light, both materials heat up, but the plain polymer nanofiber layer on the left retains the heat far longer than the composite at right.

[…]

The nanocomposite combines one-dimensional polymer nanofibers and two-dimensional boron nitride nanosheets. The nanofibers reinforce the self-assembling material while the “white graphene” nanosheets provide a thermally conductive network that allows it to withstand the heat that breaks down common dielectrics, the polarized insulators in batteries and other devices that separate positive and negative electrodes.

The discovery by the lab of Rice materials scientist Pulickel Ajayan is detailed in Advanced Functional Materials.

Read more.

qingzinano: Nano-microfiber Composites For F…

qingzinano:

Nano-microfiber Composites For Filtration

Nanofibers prepared by molecular self-assembly are in general not self-supporting and therefore require stabilizing scaffold structures. In fact, a lot of research in the past has been done with supramolecular self-assembly of molecules forming a network of nanofibers used as organo/hydrogelators. But efforts to use them as a self-standing membrane or as free fibers were not strong. Therefore, the self-assembly of trisamides was also tried on a substrate, i.e., other microfiber nonwovens, leading to microenanofiber composites (Fig. 4.4) used for filtration (Weiss et al., 2016).

Do NOT follow this link or you will be banned from the site!