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Well, it's maybe a bit premature, but if they can replace metal with ligthweight plastic it could be a real boost to space exploration.
Mother-of-pearl inspires super-strong plastic
* 19:00 04 October 2007
* NewScientist.com news service
* Tom Simonite
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It looks like a sandwich wrapper but this sheet is as tough as steel, thanks to a new technique that can make the strengths of nanostructures on a much larger scale (
A plastic made at room temperature from clay and a common ingredient of paint and glue is a strong as steel and a match for materials made using much higher temperatures.
The substance mimics the structure of mother-of-pearl, and its creators say further development of their new technique could provide lighter body armour, as well as aircraft and vehicle parts.
Engineer Nicholas Kotov and colleagues at University of Michigan at Ann Arbor, US, have solved a problem that has baffled materials scientists for more than 30 years.
"When you tried to build something you can hold in your arms, there were difficulties transferring the strength of individual nanosheets or nanotubes to the entire material," Kotov explains.
Nanotubes and other structures have impressive mechanical strength, but getting them to take the strain in a composite material is not easy. Instead the other materials used to hold them together bear the brunt and buckle, snap or tear instead. The new material, however, is stiffer than any nanotube fibres made to date.
Unique properties
Kotov's team used a new manufacturing process to make the new plastic from a polymer called polyvinyl alcohol (PVA) commonly used in paints and glue, and nano-sized sheets of mineral that make up a particular clay called Montmorillonite. The 1 nanometre thick by 10 nm square particles of the clay mineral are very strong. PVA is not, but is very good at enveloping and bonding to small particles.
To create the new material, the team use a robotic arm that builds up layers, one material at a time. It dips a piece of glass into the PVA solution and then into a solution containing the clay particles. Once those two layers have dried, the process starts again. It took 300 layers of each material to produce a sheet of material the thickness of a piece of plastic sandwich wrap.
The transparent sheet's response to stress would earn it the name "plastic steel" says Kotov, if it was a bit more elastic. It has similar properties to Kevlar, and some strong ceramic materials, all of which require much more energy to make.
"It is hard to imagine that a combination of pretty mundane everyday materials like clay and PVA can give such unique mechanical properties," says Kotov. Stiffness and tensile strength are at least 10 times greater than any other nanocomposite made before, he adds.
'Velcro effect'
Two features give the material its strength. Firstly, the layered structure allows the particles in the clay to stack into a "bricks-and-mortar" arrangement that braces them against one another. The arrangement is similar one of nature's strongest materials – mother-of-peal, or nacre – which is built up in layers by the molluscs that line their shells with it.
Second, the mix of PVA and clay forms strong but not permanent hydrogen bonds between the layers. That allows what Kotov calls a "Velcro effect" where they break and reform under stress.
Kotov and colleagues are now working a process to make larger areas of the plastic, and with new variations on the technique.
Journal reference: Science (vol 318, p 80)
Mother-of-pearl inspires super-strong plastic
* 19:00 04 October 2007
* NewScientist.com news service
* Tom Simonite
Printable versionEmail to a friendRSS FeedSyndicate
It looks like a sandwich wrapper but this sheet is as tough as steel, thanks to a new technique that can make the strengths of nanostructures on a much larger scale (
A plastic made at room temperature from clay and a common ingredient of paint and glue is a strong as steel and a match for materials made using much higher temperatures.
The substance mimics the structure of mother-of-pearl, and its creators say further development of their new technique could provide lighter body armour, as well as aircraft and vehicle parts.
Engineer Nicholas Kotov and colleagues at University of Michigan at Ann Arbor, US, have solved a problem that has baffled materials scientists for more than 30 years.
"When you tried to build something you can hold in your arms, there were difficulties transferring the strength of individual nanosheets or nanotubes to the entire material," Kotov explains.
Nanotubes and other structures have impressive mechanical strength, but getting them to take the strain in a composite material is not easy. Instead the other materials used to hold them together bear the brunt and buckle, snap or tear instead. The new material, however, is stiffer than any nanotube fibres made to date.
Unique properties
Kotov's team used a new manufacturing process to make the new plastic from a polymer called polyvinyl alcohol (PVA) commonly used in paints and glue, and nano-sized sheets of mineral that make up a particular clay called Montmorillonite. The 1 nanometre thick by 10 nm square particles of the clay mineral are very strong. PVA is not, but is very good at enveloping and bonding to small particles.
To create the new material, the team use a robotic arm that builds up layers, one material at a time. It dips a piece of glass into the PVA solution and then into a solution containing the clay particles. Once those two layers have dried, the process starts again. It took 300 layers of each material to produce a sheet of material the thickness of a piece of plastic sandwich wrap.
The transparent sheet's response to stress would earn it the name "plastic steel" says Kotov, if it was a bit more elastic. It has similar properties to Kevlar, and some strong ceramic materials, all of which require much more energy to make.
"It is hard to imagine that a combination of pretty mundane everyday materials like clay and PVA can give such unique mechanical properties," says Kotov. Stiffness and tensile strength are at least 10 times greater than any other nanocomposite made before, he adds.
'Velcro effect'
Two features give the material its strength. Firstly, the layered structure allows the particles in the clay to stack into a "bricks-and-mortar" arrangement that braces them against one another. The arrangement is similar one of nature's strongest materials – mother-of-peal, or nacre – which is built up in layers by the molluscs that line their shells with it.
Second, the mix of PVA and clay forms strong but not permanent hydrogen bonds between the layers. That allows what Kotov calls a "Velcro effect" where they break and reform under stress.
Kotov and colleagues are now working a process to make larger areas of the plastic, and with new variations on the technique.
Journal reference: Science (vol 318, p 80)
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