That mine runs fully automated ore trucks and the owner Rio Tinto wants to automate the rest. 950 ppl produce 18% of the world's iron ore from that pit.
Isn't the tradition that something reaches mass market before whatever suppression and disinformation campaigns, paid for by the industry, before there's a strong enough response and therefore reaction by elected officials - who otherwise don't pay attention to such issues? Hopefully it's not harmful/toxic, but we don't seem to have an apparatus that counters the above influence; sugar, cigarettes, asbestos, etc.
I agree with concerns about recyclability. I would also raise concerns about the renewability and/or toxicity of the base materials. If they are petroleum-based, this feels like a losing proposition.
Unfortunately the recyclability and the lack of toxicity are contradictory, they cannot be satisfied simultaneously for this kind of materials.
As long as the 2-dimensional polymeric sheets do not decompose, they will not be toxic, as they cannot enter a living cell (in the form of fine dust they could cause the same problems as any mineral dust, e.g. respiratory damage through purely mechanical action).
However if they do not decompose, they can be recycled only by burning.
If they can be decomposed into monomers by heat, light or chemicals, then the monomer can be recycled. However in that case some spontaneous decomposition will also occur in old objects made of the 2-dimensional polymer and the released monomer molecules would cause toxicity problems.
So only one of these 2 features must be chosen and optimized.
Plastics can be toxic by leaching additives without the polymer itself breaking down. Moreover, much of the damage caused by microplastics (i.e. only mechanically broken down) is poorly understood. At the very least, they seem to harbour novel collections of microbes that aren't necessarily benign.
Poly(lactic acid) can be decomposed into lactate monomers by water, and the released lactate monomer can be oxidized to pyruvate and used as food by the Krebs cycle, or converted to glucose via gluconeogenesis. The lethal dose is in the grams per kilogram, so it won't cause toxicity problems.
The article mentions that it's melamine, which we currently find in Magic Erasers. It isn't recyclable or biodegradable, but seems to be non-toxic enough to be a regular fixture in the household cleaning arsenal.
It would be far better to use it as (long-lived) building material than as a sponge that quickly degrades and gets rinsed down the drain.
It is quite certain that a 2-dimensional polymer cannot be recycled like metal, glass or a thermoplastic material, i.e. by remelting or by plastic deformation at high temperatures, because a 2-dimensional polymer cannot be deformed without breaking covalent bonds and it cannot flow in a liquid state.
So this new material might behave like the existing cured polymeric resins, e.g. epoxy resins, which form a 3-dimensional network of covalent bonds after curing, so they cannot be melted, and which when heated decompose before melting. Such materials can usually be recycled only by burning.
Nonetheless, there might be a more complex way to recycle the new materials, if the new materials would decompose in monomer molecules when heated or if there would exist some solvent able to break the bonds between monomer molecules, transforming the solid 2-dimensional polymer into a solution of the monomer molecules.
If such a method to depolymerize the 2-dimensional polymer would exist, the obtained monomer could be reused to synthesize again 2-dimensional polymers.
If the depolymerization is impossible then these materials would be used in the same way like the already existing and widely used insoluble and infusible polymeric resins.
More important for their success is what processing methods will be applicable for them. After the 2-dimensional sheets are formed, they cannot be processed by any of the popular methods, e.g. injection in a mold. The thermoset polymers behave similarly after curing, but they are produced in a state where they are only partially polymerized in 1-dimensional molecules, so they can be molded in the final shape and the complete polymerization happens later.
For now, it seems that these new 2-dimensional polymers can be made only as sheets, and then you must cut them in the shapes that you need, which will waste material in comparison with making the same shape from a thermoplastic or thermoset material.
Another problem not mentioned is that of the fracture toughness. They have made some tensile strength measurements and there is no doubt that the 2-dimensional polymers will have outstanding tensile strength. However the problem is which will be their fracture toughness for bending. Graphite has a similar structure and it also has excellent tensile strength in the direction parallel with the sheets, but it is also extremely fragile when you bend it.
An advantage of the 1-dimensional polymers is that they, like metals, can be deformed without breaking covalent bonds, which results in high fracture toughness for metals and 1-dimensional polymers, unlike the substances with 2-dimensional networks of covalent bonds (e.g. graphite) or 3-dimensional networks of covalent bonds (e.g. diamond), which are fragile.
So more research is needed to determine how useful these 2-dimensional polymers can really be.
In any case, just achieving their synthesis is already a very impressive result.
Your answer illustrates why, after all these years, HN is still one of the best places to lurk. As someone who forgot most of what he learned in HS chemistry, and didn’t take any collegiate courses, what material would you recommend to learn about this stuff?
I am sorry but I cannot give a good recommendation as some years have passed since I have last searched for chemistry books in this domain.
If you go to Amazon and you search, e.g., for "Polymer Chemistry" and for "Materials Chemistry", you will find much more than 100 books. However I do not know which are the best among the recent books.
A less risky way than ordering such a book, and finding after paying for it that it is a dud, would be to go to an online site like Library Genesis, search there for such books (there are plenty), browse through them and maybe, if you find what you need, choose one or more to buy in printed form.
Alternatively, you can read the Amazon reviews for such books, to determine which would be worthy. The Amazon reviews for such specialized items as a science book are usually more trustworthy than for items of general interest.
Not the person you're replying to but William D Callister's Material Science and Engineering is a pretty standard engineering book I've seen used in my different universities across 2 continents (and have studied from too), so I'm going to say that it's a good starting point.
You seem to be assuming that the 2D polymers extend indefinitely. If instead their growth is limited such that the molecules tile, overlap, and layer, they may be more amenable to manipulation such as thermoforming, thermosetting, etc.
The paper claims that they have obtained 2D sheets of very large extent, not small flakes that can overlap.
The advantages that they claim over conventional polymers, e.g. inpermeability and high tensile strength, are conditioned by such large extents. If the 2D sheets would be small enough to slide over each other and insert between other sheet fragments, so that plastic deformation would be possible, then they would also lose any advantages over traditional polymers.
> If the 2D sheets would be small enough to slide over each other and insert between other sheet fragments, so that plastic deformation would be possible, then they would also lose any advantages over traditional polymers.
I suspect that as with many composites, these qualities fall along a spectrum, and that there are significant nonlinearities (as in "a little goes a long way") that can be usefully exploited.
Too bad the article does not actually say what the material is made out of. Does this beat UHWMPE? Because UHMWPE is already damn strung stuff for its weight. But the big downside being that because it is so damn dense it cannot be thermoformed (the big plus being that it also has a huge range of temperature resistance)
edit:
Correction, it looks like they call it "polyaramide" which sounds like it is similar to Aramid like Kevlar. Interesting
> For the monomer building blocks, they use a compound called melamine, which contains a ring of carbon and nitrogen atoms. Under the right conditions, these monomers can grow in two dimensions, forming disks. These disks stack on top of each other, held together by hydrogen bonds between the layers, which make the structure very stable and strong.
I recall hearing similar claims of graphene a while back. I realize that the lag time between academic proof-of-concept and commercial availability is large, but I still haven't heard of any products coming out that are made of graphene. Do these materials' use cases overlap?
That doesn't help if it expands differently from the rebar and concrete. One of the advantages of rebar is that it has a similar coefficient of thermal expansion so when there are temperature changes the concrete and rebar expand and contract in sync and don't have stresses from that.
Lots of problem here - it doesn't expand/contract at the same rate.
So it will likely delaminate over time.
It is also not inert.
So it may in fact, be attacked by soil PH, etc (maybe not, not enough info in the article).
Also, one of the problems with coating most things is achieving good enough adhesion that it both doesn't delaminate, and that molecules can't slip through.
There are already very good non-steel rebar - fiberglass. Many manufacturers, easily searchable. I'm astonished it hasn't completely taken over the construction industry, as rusting steel rebar expands and destroys the concrete it is supposed to be reinforcing (concrete is great in compression, lousy in tension).
Can't wait for 3D printed parts made out of this stuff.
> the new material’s elastic modulus — a measure of how much force it takes to deform a material — is between four and six times greater than that of bulletproof glass. They also found that its yield strength, or how much force it takes to break the material, is twice that of steel, even though the material has only about one-sixth the density of steel.
That's going to make for some fun prints.
Edit: density of steel is 7.85 g/cm3 and 1/6 of that is 1.3 which makes it less dense than wood! (1.5 g/cm3) It floats!
It's hard to say without reading the paper itself, but in general one should be skeptical of claims that such-and-such material is stronger than steel. The properties that make steel interesting are not its elastic modulus or yield strength.
This material is probably closer to graphite (which beats steel in elastic modulus and yeild strength) than something you would actually want to use in a structural application. It will probably be ~very~ difficult to print.
It's dirt cheap and incredible versatile. It has many different crystal structures that can give you an incredibly wide range of properties. General purpose mild steel used in buildings. Stainless steel that resists corrosion. Maraging steels used in aerospace.
Also, the high modulus is interesting. Some components are stiffness limited such that you couldn't use aluminum or titanium even if you wanted.
Well, its elastic modulus and yield strength are pretty important, actually. Being stiff and strong is pretty fundamental to a lot of its uses. It's stiffer and stronger than most other everyday materials and virtually all everyday plastic materials. Glass, quartz, alumina, zirconia, and porcelain are stiffer than steel, and glass can be stronger, but they're all brittle rather than plastic, which is pretty inconvenient and often makes them very weak in tension. Wood, most other fired clay, aluminum, brass, nearly all organic polymers, mica, cotton, dirt, etc., are much floppier and weaker than steel.
But there are a lot of metals that are somewhat stiffer and stronger than steel, like chromium, platinum, and tungsten, while still being somewhat plastic. The great advantage that steel has over them is that it's unbelievably cheap. It's even cheaper than brass, bronze, and lead!
Plasticity (ductility and malleability) is important for a couple of reasons. First, as I mentioned above, it greatly increases the fraction of the material's theoretical strength you can get in practice. Second, it allows you to form the material instead of cutting it to shape. That's the property you're using when you wrap a sandwich in aluminum foil or tie a gate shut with baling wire. You can't do that with porcelain foil or porcelain rod. Third, ductile failure happens gradually rather than suddenly, which is important in some cases.
The other really interesting thing about steel is that it's hardenable. This is very significant because cutting and forming hard things is hard. So it's routine to cut or form steel in its soft state to get more or less the shape you want, harden it, and then grind it and maybe lap it to the precise shape you want. Grinding and especially lapping can be very precise and cut very hard materials, but they're very slow processes.
Finally, steel can withstand much higher temperatures than organic materials, or even most other common metals.
These are, I think, the major reason why steel has so extensively displaced what Andrew Carnegie liked to call "inferior materials".
The two main properties that make steel interesting are 1) cost 2) toughness.
Toughness in a material science sense is the ability to absorb energy before failure. This has two major components, yield strength (energy to initiate deformation) and ductility (ability to deform without fracture).
The ductility of steel (and of many other metals) is what drive their use in structural applications, whereas many materials, i.e. ceramics, have higher yield strength but almost no ductility. Even though many glasses are "stronger than steel", if you drop a glass bowl and a steel bowl only one will shatter. If your I-beam shatters you are in trouble.
Steel is interesting in comparison to other metals because iron and carbon are abundant and the iron-carbon system has a lot of interesting features that can increase both strength and ductility.
It's really tough (i.e. not just strong but ductile as well i.e. able to stretch more without fracturing like a brittle material would) and relatively cheap to manufacture (both because the industrial process is scalable, and because iron is incredibly abundant). When cost isn't an issue, you don't use normal low alloy steel - you use expensive alloying elements like chromium for corrosion-resistant stainless steel or more relevant to this comparison, nickel for maraging steel which is several times as strong as ordinary steel.
Mainly it's the ability to absorb energy and punishment. Many materials have an elastic range, where if you deform it within that range, it will return to its original shape. Of those, a lot of materials, including many metals, are relatively brittle - once you push it past its "elastic limit" it just breaks. There are ways to make steel more like that too, but in general steel doesn't break at that point, it "yields" or deforms permanently (inelastically). You can keep on deforming it (and in fact it actually gets slightly stronger while you're doing that, which is an interesting feature) and it goes way way beyond what you would think possible before it finally breaks. So as a result it can absorb tons of energy, which makes it interesting for strength applications. The steel frame of a building in an earthquake for 30 seconds is absorbing tons of energy while hopefully not collapsing, or even in the worst case it at least allows a bunch of extra time for at least some of the occupants to escape. Or a steel-framed car that crashes into a pole - the steel crumples, absorbs energy, and slows the car somewhat more gradually in the process. If the frame were a brittle material it might just shatter on impact.
It's a thermoset plastic - melamine - and not very suitable for either resin or thermoplastic printing. It looks like polarized light is part of the polymerization process, to get 3d linkages, so even if you could print, you'd only get super strong layers, not necessarily strong overall prints.
How does this compare with carbon fiber-epoxy laminate for elastic modulus? I don't have a ballpark figure for bulletproof glass. Looks like a typical carbon fiber laminate has similar, if slightly higher density (around 1.5 g/cm3).
>The researchers have filed for two patents on the process they used to generate the material, which they describe in a paper appearing today in Nature. MIT postdoc Yuwen Zeng is the lead author of the study.
Anyone think they could find the patent that were filed? Or is it only once they're approved that you can see them?
The article touches on potential to use instead of steel, perhaps even in buildings. But I imagine its heat tolerance would likely kill any chances of that, no?
It's potentially a thermoset plastic in which case it should be able to resist somewhat high temperatures (maybe 300C). So not fireproof but not terrible either.
As a comparison, various types of insulation are rated for 60/90 minutes at 1000 degrees Celsius, while some types of brick are rated for 180 minutes. If this material can't sustain similar temperatures, it's unlikely it will be used in construction.
There are a bunch of standards for material fire classification, which may differ from country to country, but they're not really available to read online for free most of the time. You can do some googling around A1 fire classes, EI fire rating and so on.
A useful thing to know is that a house fire revolves around 800 degrees Celsius typically, so you should expect various materials that have a fire resistance rating to take more than that for a sustained period.
Yep. This is a very interesting material, and of course it's a research prototype -- but it's not very strong. They list the modulus as 12.7 GPa and the yield strength (= ultimate tensile strength, since the film tears) as 488 MPa.
In comparison, polyimide (PMDA-PPD), which also easily solvent processable, has a modulus of 8.9 GPa, and a yield strength of 350 MPa.
Less equal comparisons involve polymers that are molecuarly aligned by drawing, spinning, or chemical processes. Dyneema UHMEPE has a modulus of 110 GPa and a ultimate tensile strength of 3.5 GPa. Kevlar is similar; it utilizes interlocking hydrogen bonds to convey strength. Even stronger are glass fibers (>4 GPa tensile strength) or PAN carbon fiber (> 6 GPa tensile strength).
You of course lose some strength when you make composites out of fiber -- but irregardless this polymer is many times weaker and softer.
I'm familiar with the Bisalloy steels because I have them here right in front of me (metal fabricator by trade and laser cutter operator past 8 years).
Just a heads up - strength is not a single metric. There is tensile (pulling), compression, and shear (sliding) strength. There's also Young's modulus (how much something stretches), fatigue limits (steel can work perpetually with deformations under a certain threshold).
There's also specific strength (strength per kg) vs strength per volume and strength per dollar.
Steel also comes in lots of different flavors, with very different (orders of magnitude) strengths.
Yeah I was annoyed about how the article didn’t say what strength they were measuring.
Not of course saying improvement in any of those metrics is bad, but the comparison being made needs to say what is being compared, and how it compares to the existing best in class.
Also those metrics can vary with direction. For steel they're usually pretty uniform, but this new substance forms "2D sheets" so it's likely strength will be highly directional. Maximum tensile and compressive strength are likely to be 90° apart.
It can form films, which they tested because coatings for things like solar panels and cars and tools are profitable.
They also tested bulk plastic. It takes a long time to set, with hours in a gel phase, so epoxy-like mold pouring, flooring, and other bulk plastic applications are likely.
It might be awesome for bullet proof armor, safety equipment, and lightweight cordage and fabrics.
The synthesis is simple - it's an advance using polarized light at particular wavelengths in novel chemistry, probably inspired by the recent discovery in electrochemistry that can impose specific chirality on well known reactions.
> The researchers found that the new material’s elastic modulus — a measure of how much force it takes to deform a material — is between four and six times greater than that of bulletproof glass. They also found that its yield strength, or how much force it takes to break the material, is twice that of steel, even though the material has only about one-sixth the density of steel.
The problem with this is that steel is a large class of alloys, with a wide variety of properties depending on the chemical and physical makeup of an alloy. Even "types of steel" that people are familiar with - e.g. stainless steel - are not specific alloys but themselves classes of alloys. I'm not a metallurgist but I assume there are dozens if not hundreds of alloys qualifying as steel.
So when someone writes an article saying "it's stronger than steel!" that's exciting, but it's not enough information. In this case we know it's stronger by yield strength. We can say the new material's yield strength is twice that of the weakest known steel alloy, but no more than that.
You can see here, there is a wide gulf between the weakest and strongest alloys just in this chart, which only has five alloys and a handful of different treatments. Yield strength is anywhere from 210MPa to over 1600MPa, an 8x difference.
Subchart (g) in the image shows a plot of yield strength against elastic modulus, and it looks like the plot tops out around 1.4 GPa, meaning the strongest tested configuration by yield strength is weaker than that of tempered 4140 and 4340 steels, while nearly 7x stronger than hot-rolled 1020 steel. I don't know if "2D yield strength" is different than what is shown in the amesweb.info table, though.
I think you're missing the novel polymer for the steel-forest. Its a 2d polymer (spans a plane instead of forming strings, which is new) that has material properties that make it comparable to materials that we think of as strong.
The part where it gets rigorously classified can come later. The people involved with this project were themselves probably not metallurgists.
> yield strength, or how much force it takes to break the material
That's not yield strength.
Yield strength is how much force is required to permanently deform the material.
Ultimate tensile strength is the force required to break the material.
One great thing about steels is that they tend to work-harden.
Typical 250 grade mild steel, meaning it takes in excess of 250 MPa force to permanently stretch a 10mm round diameter section, usually has an ultimate tensile strength exceeding 400 MPa.
I’ve often heard that spider silk is stronger per kg (or is it per m^3?) than steel. Are they talking about pulling, compressing, sliding, or all of the above?
For those, they are actively swapped around where cost vs weight trade offs happen.
steel vs aluminum vs magnesium, vs titanium in engineering application, where for example engine blocks, airplane parts, car parts, battery components, etc. all have a long history of this.
It’s a complicated process because the trade offs are not simple cost/weight/strength.
Steel has an nearly infinite fatigue lifetime for instance, so steel springs are great.
Aluminum does not, so aluminum springs are terrible - among other things. No amount of weight savings can likely fix that problem in a useful way.
These pose big challenges in aircraft in particular where aluminum skins and fuselages make flight doable/economic, but means pressurized aircraft in particular have a finite lifespan in pressurization cycles/takeoffs and landings before they fall apart, no matter how nicely you treat them.
Several major accidents (including the top of an airliner coming off and sucking a flight attendant out over the pacific on the way to Hawaii) happened before this was fully understood.
Titanium is in theory much better, but is incredibly difficult to work with(requiring forgings in most cases, and being almost unmachinable), and very expensive as the bond it forms with oxygen is so strong the normal fluorine based processing used with Aluminum won’t work. Yeah, you read that right.
Fire danger (such as magnesium engine blocks burning) is also a non trivial thing to mitigate. Titanium can be one of the worst offenders here (powdered titanium fires can burn SAND used to try to put it out as an oxidizer), which makes working with it hazardous in some cases. Iron, which will also burn, is generally so mellow when it does that burning it is a normal operation while scrapping and cutting it and you can’t get a runaway from doing so except in truly difficult to achieve circumstances (it’s what an oxy-acetylene cutting torch is doing).
Pressurization cycles is what killed the reputation of the first commercial civilian jet, the De Havilland Comet.
The British were good in early jet design and actually introduced jet aircraft into the non-military world, but the early hulls would fail catastrophically after a certain, relatively low # of cycles, tearing the fuselage apart mid-flight and killing everyone on board. After several such incidents in short order, the entire fleet was grounded and scientists came up with solutions, but by then, the reputation of Comets was tarnished and Boeing came with a competing 707 model.
These days, the UK does not have a domestic jet manufacturer anymore.
>Several major accidents (including the top of an airliner coming off and sucking a flight attendant out over the pacific on the way to Hawaii)
It was actually an inter-island flight so lots of short flights (and therefore pressurization cycles relative to flight hours or miles). The amazing thing was that the plane was able to make an emergency landing.
Thanks for tracking down the specific incident! If I remember correctly, the obvious cycling issue got figured out pretty early (60’s?) - due to other earlier accidents, that part wasn’t a surprise and they thought they had figured out how to deal with it.
There was a presumption that like steel and several other materials, once it hit a specific low stress point the fatigue life became infinite, and that point was just so much lower for aluminum it just LOOKED like it has no infinitive fatigue life point.
> Titanium is in theory much better, but is incredibly difficult to work with(requiring forgings in most cases, and being almost unmachinable), and very expensive as the bond it forms with oxygen is so strong the normal fluorine based processing used with Aluminum won’t work. Yeah, you read that right.
I have a spoon bought from Amazon which they claim is made from titanium. [Lockheed_SR-71_Blackbird](https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird)
claims 31 aircraft made from titanium and first flew in 1964. Given they got it off the ground in 1964 and can make a spoon in 2022 what kind of machining problems are left to solve for titanium? Usually it's the other way round like make s spoon from wood for 5,000 years then make an aircraft in 1905.
If it is the same type of spoon I’m thinking of - they are indeed titanium! Forged titanium, at least the version I got.
Because it’s a small part with no significant critical tolerances, it’s also only $10-$20 for a few grams of metal, and only 5x as expensive as a typical spoon.
The equipment required to forge it is also doable in a garage due to the small surface area the forging is happening over (force required goes up as the surface area goes up - which is squared for the dimensions, so very rapidly gets very large).
It isn’t truly impossible to machine titanium (generally - like most metals the alloy, heat treatment, etc. matter a lot), it’s just so much harder and requires so much more expensive tooling that it’s hard to justify economically except in niche applications.
It’s improving though with better insert based machining tools and hardier insert material.
I’ve heard of some impressive titanium 3D printing using sintering techniques that also have a lot of promise.
Many of the alloys (many more than say aluminum) are nearly impossible due to material characteristics and do require EDM to machine.
Decades ago I happened to get a tour of the Edwards Air Force Base SR71 hangar (near the end of their effective time in service) and the machinists there were very proud of their EDM work for this reason.
Pulling (tensile), which is also the direction steel is unusually strong in (from a materials perspective).
Compression wise it’s close to a wet noodle the way it’s manufacturable (though that has more to do with cost/practical production/gathering methods - if we could get a solid chunk of it I imagine it would be pretty strong in compression).
Sliding, it’s a fiber, so very weak in that sense (barring the same scenario above). It actively flexes, so isn’t strong’
As I recall my material science, it's not so much that steel is weak in compression but, if you have a rod of steel (i.e. much longer than it is thick), if you compress it, it will buckle and shear. As you suggest--I'd have to look up the numbers--but a large cube of steel probably has similar strength with tensile and compressive loads.
ADDED: In fact, if you deform a supported I-beam you get similar amounts of tension and compression on the bottom and top respectively at the mid-point of the beam (given a variety of assumptions).
As I wrote in another comment, my material science and mechanical engineering is very rusty at this point. :-) But, yeah, I-beams basically wouldn't work if steel were weak in compression because, assuming a straightforward loading of a supported beam you're basically putting one flange of the beam in tension and the other flange in the equivalent amount of compression. So the fact that one part of the I-beam is strong would be pretty much irrelevant if the other part were weak.
Tensile, mostly, but it's not stronger, it's tougher. The other answers to your question so far are all wrong or missing the central point.
Spider silk has ultimate tensile strength comparable to some high-strength steels, around 1.4 GPa. Everyday steels are significantly weaker, around 0.4 GPa. Some steels have higher tensile strengths, like 2.6 GPa maraging steel. There are many materials with similar or higher tensile strengths: E-glass (3.5 GPa), carbon fiber (typically 4.1 GPa, 7 GPa for Toray T1100G), kevlar (3.8 GPa), zylon (5.8 GPa), boron (3.1 GPa), sapphire (1.9 GPa), diamond (2.8 GPa), graphene (130 GPa), dyneema (3 GPa). Some of these, like dyneema, are even comparable in density to spider silk. So what's so special about spider silk?
Where spider silk is outstanding is that it combines high strength with high extensibility. Think of rubber: cast iron or diamond are much stronger than a rubber tire in the sense that they can bear heavier loads on the same cross section, whether in tension, compression, or shear; but if you hit a cast iron pot or a diamond with a sledgehammer they will break, while a rubber tire will be unharmed. This is because the rubber deforms under the blow, slowing down the hammer without ever experiencing a very high force.
If you integrate the force on a spring over a distance (∫ F · dx), you get the change in the energy of the spring. If you integrate it over the spring's entire working range, you get its energy capacity as a spring. Every solid object is a spring, so you can do this for any solid object. "Stress" is force divided by cross-sectional surface area, and "strain" is extension divided by length, and the presumption of linear elasticity theory is that the stress–strain relation of a material, as well as its yield stress and breaking stress, are properties of the material rather than of particular objects made from it.
If, instead of integrating force over distance, you integrate stress over strain, you get the amount of deformation energy the material can absorb per unit volume without breaking, for example in an impact. That's the material's theoretical toughness.
All the other high-strength materials in the above list either deform plastically or break at under 10% extension; many of them break at under 0.1% extension. Spider silk breaks at 35%–500% extension. This makes some spider silks 10 times tougher than even kevlar.
Usually compressive, tensile, and shear strengths increase and decrease together; the biggest exception is when the material is full of cracks, like glass and concrete.
Exactly. We also have temperature and chemical resistance. Very important in most applications and for example an interesting discussion between rubber and polyurethane compounds.
> steel can work perpetually with deformations under a certain threshold[*]
[*] Within a temperature range of about ~-30 °C to ~400 °C. Below that and the toughness goes way down so that it's prone to cracking. Above that and carbon starts to work its way into all those crystal structure discontinuities, preventing some percentage of the strain from being relieved each stress cycle (the "creep range").
That's just for carbon steels. Stainless has a different set of problems.
Maybe? PTFE (Teflon) has a melting point around 325 °C; this plastic could be higher. The point of my comment was to qualify what the person above me stated.
Are there any samples big enough to be seen without a microscope? After a decade or more reading about nanotubes and graphene I'm a little jaded about "easily manufactured in large quantities". How long does it take to create a solid 1-foot cube? If you are comparing a new material to steel or concrete "large quantities" means multiple tons per hour. I'm going to need to see a sample bigger than a doorstop.
> Such a material could be used as a lightweight, durable coating for car parts or cell phones, or as a building material for bridges or other structures, says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the senior author of the new study.
Anyone else get immediately sidetracked by how metal the name "Carbon P. Dubbs" is? (and how unexpectedly apropos it is to chemical engineering?)
Maybe a stupid thought, but could a carbon-based building material be the best possible news for carbon sequestration? I mean, we humans need a lot of buildings.
161 comments
[ 3.7 ms ] story [ 239 ms ] threadThat seems promising.
I have a couple of concerns - Can it be recycled? - How are new materials like this tested for toxicity?
Right. We have enough issues with plastic waste, without it having extra-ordinary strength.
https://en.wikipedia.org/wiki/Yandicoogina_mine
https://www.abc.net.au/news/2015-10-18/rio-tinto-opens-world...
Microplastics haven't been proven to have much damage other than triggering karentils (karen's on lentil spectrum).
Very tiny, very sharp flakes of very strong materials could be asbestos 2.0
As long as the 2-dimensional polymeric sheets do not decompose, they will not be toxic, as they cannot enter a living cell (in the form of fine dust they could cause the same problems as any mineral dust, e.g. respiratory damage through purely mechanical action).
However if they do not decompose, they can be recycled only by burning.
If they can be decomposed into monomers by heat, light or chemicals, then the monomer can be recycled. However in that case some spontaneous decomposition will also occur in old objects made of the 2-dimensional polymer and the released monomer molecules would cause toxicity problems.
So only one of these 2 features must be chosen and optimized.
It would be far better to use it as (long-lived) building material than as a sponge that quickly degrades and gets rinsed down the drain.
1. https://livegreen.recyclebank.com/column/because-you-asked/w...
So this new material might behave like the existing cured polymeric resins, e.g. epoxy resins, which form a 3-dimensional network of covalent bonds after curing, so they cannot be melted, and which when heated decompose before melting. Such materials can usually be recycled only by burning.
Nonetheless, there might be a more complex way to recycle the new materials, if the new materials would decompose in monomer molecules when heated or if there would exist some solvent able to break the bonds between monomer molecules, transforming the solid 2-dimensional polymer into a solution of the monomer molecules.
If such a method to depolymerize the 2-dimensional polymer would exist, the obtained monomer could be reused to synthesize again 2-dimensional polymers.
If the depolymerization is impossible then these materials would be used in the same way like the already existing and widely used insoluble and infusible polymeric resins.
More important for their success is what processing methods will be applicable for them. After the 2-dimensional sheets are formed, they cannot be processed by any of the popular methods, e.g. injection in a mold. The thermoset polymers behave similarly after curing, but they are produced in a state where they are only partially polymerized in 1-dimensional molecules, so they can be molded in the final shape and the complete polymerization happens later.
For now, it seems that these new 2-dimensional polymers can be made only as sheets, and then you must cut them in the shapes that you need, which will waste material in comparison with making the same shape from a thermoplastic or thermoset material.
Another problem not mentioned is that of the fracture toughness. They have made some tensile strength measurements and there is no doubt that the 2-dimensional polymers will have outstanding tensile strength. However the problem is which will be their fracture toughness for bending. Graphite has a similar structure and it also has excellent tensile strength in the direction parallel with the sheets, but it is also extremely fragile when you bend it.
An advantage of the 1-dimensional polymers is that they, like metals, can be deformed without breaking covalent bonds, which results in high fracture toughness for metals and 1-dimensional polymers, unlike the substances with 2-dimensional networks of covalent bonds (e.g. graphite) or 3-dimensional networks of covalent bonds (e.g. diamond), which are fragile.
So more research is needed to determine how useful these 2-dimensional polymers can really be.
In any case, just achieving their synthesis is already a very impressive result.
If you go to Amazon and you search, e.g., for "Polymer Chemistry" and for "Materials Chemistry", you will find much more than 100 books. However I do not know which are the best among the recent books.
A less risky way than ordering such a book, and finding after paying for it that it is a dud, would be to go to an online site like Library Genesis, search there for such books (there are plenty), browse through them and maybe, if you find what you need, choose one or more to buy in printed form.
Alternatively, you can read the Amazon reviews for such books, to determine which would be worthy. The Amazon reviews for such specialized items as a science book are usually more trustworthy than for items of general interest.
The advantages that they claim over conventional polymers, e.g. inpermeability and high tensile strength, are conditioned by such large extents. If the 2D sheets would be small enough to slide over each other and insert between other sheet fragments, so that plastic deformation would be possible, then they would also lose any advantages over traditional polymers.
I suspect that as with many composites, these qualities fall along a spectrum, and that there are significant nonlinearities (as in "a little goes a long way") that can be usefully exploited.
https://scitechdaily.com/two-dimensional-polymers-created-fo...
Either way, looking forward to buying this stuff cheap and in bulk from McMaster!
On the other hand, I wonder what kinds of hoops one has to jump through to demolish/recycle this material.
edit:
Correction, it looks like they call it "polyaramide" which sounds like it is similar to Aramid like Kevlar. Interesting
Making it in large sizes is more difficult.
https://www.abitape.com/an-unlikely-hero-how-sticky-tape-led...
https://pubmed.ncbi.nlm.nih.gov/28278030/
Vitoria have sold bike tyres using a graphine layer for a couple of years now:
https://www.vittoria.com/ww/en/tyres/road-tires/corsa
They were used by both the winners of the Tour de France and Vuelta a Espana last year.
It is also not inert. So it may in fact, be attacked by soil PH, etc (maybe not, not enough info in the article).
Also, one of the problems with coating most things is achieving good enough adhesion that it both doesn't delaminate, and that molecules can't slip through.
If the solution chemistry is compatible with concrete then it might be mixed in and polymerize together, and that would be yet more exciting.
This material is likely brittle, probably similar in overall behavior to graphite.
> the new material’s elastic modulus — a measure of how much force it takes to deform a material — is between four and six times greater than that of bulletproof glass. They also found that its yield strength, or how much force it takes to break the material, is twice that of steel, even though the material has only about one-sixth the density of steel.
That's going to make for some fun prints.
Edit: density of steel is 7.85 g/cm3 and 1/6 of that is 1.3 which makes it less dense than wood! (1.5 g/cm3) It floats!
This material is probably closer to graphite (which beats steel in elastic modulus and yeild strength) than something you would actually want to use in a structural application. It will probably be ~very~ difficult to print.
Also, the high modulus is interesting. Some components are stiffness limited such that you couldn't use aluminum or titanium even if you wanted.
But there are a lot of metals that are somewhat stiffer and stronger than steel, like chromium, platinum, and tungsten, while still being somewhat plastic. The great advantage that steel has over them is that it's unbelievably cheap. It's even cheaper than brass, bronze, and lead!
Plasticity (ductility and malleability) is important for a couple of reasons. First, as I mentioned above, it greatly increases the fraction of the material's theoretical strength you can get in practice. Second, it allows you to form the material instead of cutting it to shape. That's the property you're using when you wrap a sandwich in aluminum foil or tie a gate shut with baling wire. You can't do that with porcelain foil or porcelain rod. Third, ductile failure happens gradually rather than suddenly, which is important in some cases.
The other really interesting thing about steel is that it's hardenable. This is very significant because cutting and forming hard things is hard. So it's routine to cut or form steel in its soft state to get more or less the shape you want, harden it, and then grind it and maybe lap it to the precise shape you want. Grinding and especially lapping can be very precise and cut very hard materials, but they're very slow processes.
Finally, steel can withstand much higher temperatures than organic materials, or even most other common metals.
These are, I think, the major reason why steel has so extensively displaced what Andrew Carnegie liked to call "inferior materials".
Toughness in a material science sense is the ability to absorb energy before failure. This has two major components, yield strength (energy to initiate deformation) and ductility (ability to deform without fracture).
The ductility of steel (and of many other metals) is what drive their use in structural applications, whereas many materials, i.e. ceramics, have higher yield strength but almost no ductility. Even though many glasses are "stronger than steel", if you drop a glass bowl and a steel bowl only one will shatter. If your I-beam shatters you are in trouble.
Steel is interesting in comparison to other metals because iron and carbon are abundant and the iron-carbon system has a lot of interesting features that can increase both strength and ductility.
Anyone think they could find the patent that were filed? Or is it only once they're approved that you can see them?
https://pubchem.ncbi.nlm.nih.gov/patent/US-2021002426-A1
A useful thing to know is that a house fire revolves around 800 degrees Celsius typically, so you should expect various materials that have a fire resistance rating to take more than that for a sustained period.
https://en.wikipedia.org/wiki/Grenfell_Tower_fire
(Not on SciHub yet but the figures provide some useful info)
Also, how does this affect the recyclability of current waste plastics?
For instance, oh, nylon fiber is stronger than some steels, and way less dense:
https://en.wikipedia.org/wiki/Ultimate_tensile_strength#Typi...
One kind of steel, "ASTM steel" comes in at 400-500 MPa; nylon fibers at 900.
Check out the Bamboo entry in the table. Human hair is also impressive.
In comparison, polyimide (PMDA-PPD), which also easily solvent processable, has a modulus of 8.9 GPa, and a yield strength of 350 MPa.
Less equal comparisons involve polymers that are molecuarly aligned by drawing, spinning, or chemical processes. Dyneema UHMEPE has a modulus of 110 GPa and a ultimate tensile strength of 3.5 GPa. Kevlar is similar; it utilizes interlocking hydrogen bonds to convey strength. Even stronger are glass fibers (>4 GPa tensile strength) or PAN carbon fiber (> 6 GPa tensile strength).
You of course lose some strength when you make composites out of fiber -- but irregardless this polymer is many times weaker and softer.
BIS80 has a yield strength in excess of 620 Mpa, and an ultimate tensile strength in the range 720 to 930 Mpa.
See here for more info https://www.bisalloy.com.au/wp-content/uploads/2020/06/BISAL...
BIS100 has a yield strength around the 890 MPa mark, and an ultimate tensile strength in the range 940 to 1100 MPa.
See here for more info https://www.bisalloy.com.au/wp-content/uploads/2020/06/BISAL...
Nylon is lighter, but it also loses about 20% of its tensile strength when wet.
I'm familiar with the Bisalloy steels because I have them here right in front of me (metal fabricator by trade and laser cutter operator past 8 years).
There's also specific strength (strength per kg) vs strength per volume and strength per dollar.
Steel also comes in lots of different flavors, with very different (orders of magnitude) strengths.
Not of course saying improvement in any of those metrics is bad, but the comparison being made needs to say what is being compared, and how it compares to the existing best in class.
They also tested bulk plastic. It takes a long time to set, with hours in a gel phase, so epoxy-like mold pouring, flooring, and other bulk plastic applications are likely.
It might be awesome for bullet proof armor, safety equipment, and lightweight cordage and fabrics.
The synthesis is simple - it's an advance using polarized light at particular wavelengths in novel chemistry, probably inspired by the recent discovery in electrochemistry that can impose specific chirality on well known reactions.
So when someone writes an article saying "it's stronger than steel!" that's exciting, but it's not enough information. In this case we know it's stronger by yield strength. We can say the new material's yield strength is twice that of the weakest known steel alloy, but no more than that.
A quick look around found this:
https://amesweb.info/Materials/Steel-Tensile-Yield-Strength-...
You can see here, there is a wide gulf between the weakest and strongest alloys just in this chart, which only has five alloys and a handful of different treatments. Yield strength is anywhere from 210MPa to over 1600MPa, an 8x difference.
This page has some charts for the new material:
https://www.researchgate.net/figure/Mechanical-properties-of...
Subchart (g) in the image shows a plot of yield strength against elastic modulus, and it looks like the plot tops out around 1.4 GPa, meaning the strongest tested configuration by yield strength is weaker than that of tempered 4140 and 4340 steels, while nearly 7x stronger than hot-rolled 1020 steel. I don't know if "2D yield strength" is different than what is shown in the amesweb.info table, though.
That's not yield strength.
Yield strength is how much force is required to permanently deform the material.
Ultimate tensile strength is the force required to break the material.
One great thing about steels is that they tend to work-harden.
Typical 250 grade mild steel, meaning it takes in excess of 250 MPa force to permanently stretch a 10mm round diameter section, usually has an ultimate tensile strength exceeding 400 MPa.
For instance, many aluminum alloys have about 60-80% the tensile strength of steel, but only 1/3rd the weight.
For those, they are actively swapped around where cost vs weight trade offs happen.
steel vs aluminum vs magnesium, vs titanium in engineering application, where for example engine blocks, airplane parts, car parts, battery components, etc. all have a long history of this.
It’s a complicated process because the trade offs are not simple cost/weight/strength.
Steel has an nearly infinite fatigue lifetime for instance, so steel springs are great.
Aluminum does not, so aluminum springs are terrible - among other things. No amount of weight savings can likely fix that problem in a useful way.
These pose big challenges in aircraft in particular where aluminum skins and fuselages make flight doable/economic, but means pressurized aircraft in particular have a finite lifespan in pressurization cycles/takeoffs and landings before they fall apart, no matter how nicely you treat them.
Several major accidents (including the top of an airliner coming off and sucking a flight attendant out over the pacific on the way to Hawaii) happened before this was fully understood.
Titanium is in theory much better, but is incredibly difficult to work with(requiring forgings in most cases, and being almost unmachinable), and very expensive as the bond it forms with oxygen is so strong the normal fluorine based processing used with Aluminum won’t work. Yeah, you read that right.
Fire danger (such as magnesium engine blocks burning) is also a non trivial thing to mitigate. Titanium can be one of the worst offenders here (powdered titanium fires can burn SAND used to try to put it out as an oxidizer), which makes working with it hazardous in some cases. Iron, which will also burn, is generally so mellow when it does that burning it is a normal operation while scrapping and cutting it and you can’t get a runaway from doing so except in truly difficult to achieve circumstances (it’s what an oxy-acetylene cutting torch is doing).
The British were good in early jet design and actually introduced jet aircraft into the non-military world, but the early hulls would fail catastrophically after a certain, relatively low # of cycles, tearing the fuselage apart mid-flight and killing everyone on board. After several such incidents in short order, the entire fleet was grounded and scientists came up with solutions, but by then, the reputation of Comets was tarnished and Boeing came with a competing 707 model.
These days, the UK does not have a domestic jet manufacturer anymore.
Per your last point, BAE and Hawker are still around. The UK also does plenty of Airbus work.
The manufacturers you mentioned are all military or regulatory sop manufacturers no? Though I guess Boeing isn’t much better, so meh.
It was actually an inter-island flight so lots of short flights (and therefore pressurization cycles relative to flight hours or miles). The amazing thing was that the plane was able to make an emergency landing.
https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243
I would have suspected this story was out of the early days of the big airliners.
There was a presumption that like steel and several other materials, once it hit a specific low stress point the fatigue life became infinite, and that point was just so much lower for aluminum it just LOOKED like it has no infinitive fatigue life point.
It turns out they were wrong.
> Titanium is in theory much better, but is incredibly difficult to work with(requiring forgings in most cases, and being almost unmachinable), and very expensive as the bond it forms with oxygen is so strong the normal fluorine based processing used with Aluminum won’t work. Yeah, you read that right.
I have a spoon bought from Amazon which they claim is made from titanium. [Lockheed_SR-71_Blackbird](https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird) claims 31 aircraft made from titanium and first flew in 1964. Given they got it off the ground in 1964 and can make a spoon in 2022 what kind of machining problems are left to solve for titanium? Usually it's the other way round like make s spoon from wood for 5,000 years then make an aircraft in 1905.
Because it’s a small part with no significant critical tolerances, it’s also only $10-$20 for a few grams of metal, and only 5x as expensive as a typical spoon.
The equipment required to forge it is also doable in a garage due to the small surface area the forging is happening over (force required goes up as the surface area goes up - which is squared for the dimensions, so very rapidly gets very large).
Compare that to say an engine block, wing spar in an airplane, or fighter jet bulkhead [https://www.businesswire.com/news/home/20151007005865/en/Alc...] and it gets dramatically more expensive and harder.
It isn’t truly impossible to machine titanium (generally - like most metals the alloy, heat treatment, etc. matter a lot), it’s just so much harder and requires so much more expensive tooling that it’s hard to justify economically except in niche applications.
It’s improving though with better insert based machining tools and hardier insert material.
I’ve heard of some impressive titanium 3D printing using sintering techniques that also have a lot of promise.
Many of the alloys (many more than say aluminum) are nearly impossible due to material characteristics and do require EDM to machine.
Decades ago I happened to get a tour of the Edwards Air Force Base SR71 hangar (near the end of their effective time in service) and the machinists there were very proud of their EDM work for this reason.
Titanium is distinguished from steel, besides its raw strength/wt, in that it can be stretched a great deal without ever developing stress cracks.
People were very impressed when Russia took to making whole submarines out of titanium.
Compression wise it’s close to a wet noodle the way it’s manufacturable (though that has more to do with cost/practical production/gathering methods - if we could get a solid chunk of it I imagine it would be pretty strong in compression).
Sliding, it’s a fiber, so very weak in that sense (barring the same scenario above). It actively flexes, so isn’t strong’
ADDED: In fact, if you deform a supported I-beam you get similar amounts of tension and compression on the bottom and top respectively at the mid-point of the beam (given a variety of assumptions).
Not just similar, but pretty much identical from what I recalled from my uni classes. Wikipedia for structural materials (https://en.wikipedia.org/wiki/Structural_material) also has this bit -
>Steel is equally strong in tension and compression.
Spider silk has ultimate tensile strength comparable to some high-strength steels, around 1.4 GPa. Everyday steels are significantly weaker, around 0.4 GPa. Some steels have higher tensile strengths, like 2.6 GPa maraging steel. There are many materials with similar or higher tensile strengths: E-glass (3.5 GPa), carbon fiber (typically 4.1 GPa, 7 GPa for Toray T1100G), kevlar (3.8 GPa), zylon (5.8 GPa), boron (3.1 GPa), sapphire (1.9 GPa), diamond (2.8 GPa), graphene (130 GPa), dyneema (3 GPa). Some of these, like dyneema, are even comparable in density to spider silk. So what's so special about spider silk?
Where spider silk is outstanding is that it combines high strength with high extensibility. Think of rubber: cast iron or diamond are much stronger than a rubber tire in the sense that they can bear heavier loads on the same cross section, whether in tension, compression, or shear; but if you hit a cast iron pot or a diamond with a sledgehammer they will break, while a rubber tire will be unharmed. This is because the rubber deforms under the blow, slowing down the hammer without ever experiencing a very high force.
If you integrate the force on a spring over a distance (∫ F · dx), you get the change in the energy of the spring. If you integrate it over the spring's entire working range, you get its energy capacity as a spring. Every solid object is a spring, so you can do this for any solid object. "Stress" is force divided by cross-sectional surface area, and "strain" is extension divided by length, and the presumption of linear elasticity theory is that the stress–strain relation of a material, as well as its yield stress and breaking stress, are properties of the material rather than of particular objects made from it.
If, instead of integrating force over distance, you integrate stress over strain, you get the amount of deformation energy the material can absorb per unit volume without breaking, for example in an impact. That's the material's theoretical toughness.
All the other high-strength materials in the above list either deform plastically or break at under 10% extension; many of them break at under 0.1% extension. Spider silk breaks at 35%–500% extension. This makes some spider silks 10 times tougher than even kevlar.
Usually compressive, tensile, and shear strengths increase and decrease together; the biggest exception is when the material is full of cracks, like glass and concrete.
[*] Within a temperature range of about ~-30 °C to ~400 °C. Below that and the toughness goes way down so that it's prone to cracking. Above that and carbon starts to work its way into all those crystal structure discontinuities, preventing some percentage of the strain from being relieved each stress cycle (the "creep range").
That's just for carbon steels. Stainless has a different set of problems.
If the new material is plastic-like, it may have worse issues here?
As a layman, I greatly enjoyed this one as a primer.
Anyone else get immediately sidetracked by how metal the name "Carbon P. Dubbs" is? (and how unexpectedly apropos it is to chemical engineering?)
https://digging-history.com/2016/01/18/tombstone-tuesday-car...
Apparently his full name was "Carbon Petroleum Dubbs" and the relation to chemical engineering isn't really coincidental.
Will it fill the oceans with indestructible junk?