Material Science News and Discussions

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Strong shape-memory adhesive could put Spider-Man to shame
By Michael Irving
May 02, 2024

https://newatlas.com/materials/spiderma ... -adhesive/
You can stop skulking around labs trying to get bitten by radioactive spiders – a new breakthrough could make it easier than ever to get Spider-Man’s wall-crawling powers. Scientists in Singapore have created a strong and reusable adhesive out of a shape-memory polymer, sticking to and detaching from surfaces by changing the temperature.

The polymer is called E44 epoxy, and at room temperature it’s a stiff and glassy plastic, but once heated up it becomes soft and rubbery. In that state, it can ooze into the tiny crannies and crevices of another surface, allowing it to form extra-strong bonds if it’s then cooled down. If you later want to remove it, all you need to do is heat it back up.

In tests conducted by scientists at Nanyang Technological University (NTU) Singapore, the adhesive was able to grab onto a range of different textures and didn’t leave any sticky residue behind. Through experimentation, the team found that the best shape for the material was a series of hair-like structures called fibrils, each a few millimeters wide.

For example, one setup used fibrils with a cross section of 19.6 mm2 (0.03 in2), with each being able to hold up to 1.56 kg (3.4 lb). Adding more fibrils increases the maximum weight the material can hold, with a palm-sized pad of 37 fibrils holding a 60-kg (132-lb) weight.

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Long-life low-carbon concrete switches 80% of its cement for coal ash
By Loz Blain
May 21, 2024

RMIT researchers have developed a new type of "green concrete" that incorporates twice as much recycled coal ash as existing low-carbon concretes, halves the amount of cement required, and lasts even longer than regular Portland cement concrete.

Coal ash is abundant around coal-fired power stations. In fact, that might be considerably understating things – globally, power stations produce around 1.2 billion tonnes annually, and in Australia coal ash accounts for nearly 20% of all waste. It's a staggering figure – and it's also a safe bet that this stuff will remain abundant long into the renewable energy transition.

Hence, it's an enormous potential material resource, and low-carbon concrete manufacturers have been using it as a cement substitute, typically replacing up to 40% of the cement. In an environmental sense, this kills two birds with one stone, making use of a massive waste product while cutting down on cement – which by itself accounts for somewhere around 8% of all global carbon emissions.

https://newatlas.com/materials/rmit-ash-concrete/

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Game-changing nanostrings vibrate longer than any solid-state material
By Michael Franco
May 22, 2024

"Imagine a swing that, once pushed, keeps swinging for almost 100 years because it loses almost no energy through the ropes." So says a Delft University of Technology researcher who has helped his team accomplish a parallel feat at the nanoscale.

In creating their super-vibrational nanostrings, Norte and his fellow TU Delft colleagues – along with scientists from Brown University – stretched out a strand of extremely resilient silicon nitride (Si3N4) to a length of 3 cm (1.2 in) while maintaining it at a thickness of just 70 nanometers. This is "equivalent to reliably producing ceramic structures with a thickness of one millimeter, suspended over nearly half a kilometer," write the researchers in a paper published in Nature Communications.

"Our manufacturing process goes in a different direction with respect to what is possible in nanotechnology today," says study co-author Andrea Cupertino, also from TU Delft.

"These kinds of extreme structures are only feasible at nanoscales where the effects of gravity and weight enter differently," she adds. "This allows for structures that would be unfeasible at our everyday scales but are particularly useful in miniature devices used to measure physical quantities such as pressure, temperature, acceleration and magnetic fields, which we call MEMS sensing."

Once the nanostrings were manufactured, they were clamped above a microchip. The strings were then shown to be able to vibrate 100,000 times per second without losing much momentum at ambient temperatures. Such a feat has previously only been exhibited by materials near absolute zero temperatures.

"The newly developed nanostrings boast the highest mechanical quality factors ever recorded for any clamping object in room temperature environments; in their case clamped to a microchip," says the TU Delft report.

https://newatlas.com/materials/nanostri ... te-longer/

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'Absolute miracle' breakthrough provides recipe for zero-carbon cement
By Michael Irving
May 23, 2024
https://newatlas.com/materials/concrete ... on-cement/

Concrete and steel production are major sources of CO2 emissions, but a new solution from Cambridge could recycle both at the same time. Throwing old concrete into steel-processing furnaces not only purifies iron but produces “reactivated cement” as a byproduct. If done using renewable energy, the process could make for completely carbon-zero cement.

Concrete is the world’s most used building material, and making it is a particularly dirty business – concrete production alone is responsible for about 8% of total global CO2 emissions. Unfortunately it’s not easy to recycle back into a form that can be used to make new concrete structures.