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A Liquid That Turns Solid When Heated
Roland Piquepaille writes "There are some sure things in life, such as death and taxes. When you are heating a solid, you expect it will melt and when you're boiling water, you're pretty certain that it will turn into vapor. But what about a liquid that becomes solid when it's heated? Of course, it has already been done, for example in the chemical process of polymerization. But now, PhysicsWeb writes that a team of French physicists has discovered a law-breaking liquid that defies the rules. When you heat it between 45 and 75C, it becomes solid. But the process is fully reversible, and this is a world's premiere. When you decrease the temperature, this solid melts and turns again into a liquid. I'm not sure of the implications of such a phenomenon, but it's fascinating. Read more for essential details."
Which law would this be? The one that says solids melt into liquids at higher temperatures? Oh wait, there is no such law - thanks to something called Sublimiation where solids go straight to a gas (like dry ice).
This is not an example of a new found element with impossible thermal properties. This is an example of materials and molecular chemistry in action. This works because it follows the laws of physics.
That would probably depend on the property of the solid that forms when the solution is heated (is it a good insulator? what are its structural properties?), but I can think of one related application: temperature-controlled switch.
The solution is transparent to visible light, whereas the solid that forms is not. Since this process depends on the temperature and is reversible, it's very simple to design a circuit (using a LED and phototransistor or some sort of photo-detector) that works as temperature-dependent switch. From what the article says,
The temperature at which it becomes a solid falls as the concentration of CD increases.
it should be possible to tweak the turn-on temperature to a degree.
But then, this is not anything new--as far as dependence on temperature goes, there are many other materials that are probably more reliable (the only thing novel about this would be that its dependence is backward.)
Back to the topic, yeah, it can probably be used as heat shield in a limited capacity: i.e. if it turns out that the liquid is transparent to infrared radiation while the solid isn't, this can be used as natural temperature-controlled infrared radiation shield (but of course, it will still be subject to heating due to other methods, like...conduction via the solid itself, unless the resulting solid turns out to be similar to styroform).
I wouldn't be too sure about that.
Bose-Einstein Condensate
Superfluids
First rule of physics: When you're dealing with extremes, things get funky.
Secondly, based on the types of compounds in the solution, and the description in the article, the "solid" is probably more of a waxy/jelly sort of substance.
That said, your idea could be made to work in other cases. I wonder if maybe the substance could be altered for use as a variable damping material for suspension or acoustic purposes.
Can someone explain the phrase 'sol-gel'? Does that mean that it become more like a gelatinous subject when heated instead of a more 'solid' solid?
Sols aren't solids. A "sol" is a colloid solution, so is a gel. Without getting too deep into the chemistry, he's basically saying it's a gel.
(Look up 'sol', 'gel', 'dispersion' and 'colloid' for more details)
cyclodextrin? Probably. It's starch.
water? Definitely.
4-methylpyridine? Probably causes cancer. Known to cause damage to the central nervous system. In simple words: Poision.
From Haldex:
Something tells me having hydralic fluid that turns solid when it gets hot wouldn't help a system like thisTo blog is sublime
To a physicist the phase diagram is interesting, because the solid/gel must have a larger entropy than the corresponding liquid. (Remember that you calculate equilibrium by minimizing the Gibbs energy G = H - TS).
Anyway it has been known for many years that some triblock polymers form gels when heated, but perhaps the solid phase of this new liquid is "more solid". Perhaps the news is that the liquid has a larger enthalpy of melting. I don't know
You're talking about a standard 'wet' limited slip differential, or LSD. Wet LSD's have a viscous solution inside that, as the spider gears generate friction by spinning opposite directions, solidifies to unify power delivery from the driveshaft. An open differential allows wheels to spin at differing speeds, usually giving more power to the wheel that's spinning more freely. This is bad in racing. It's also bad for 4wd cars like the Subaru WRX or the Mitsubishi Evolution VIII. Both cars have LSD standard.
The other type of LSD is a clutch-plate type. These can be adjusted for resistance to slippage by arranging the type and order of clutch plates in the LSD. A viscous LSD on the other hand is governed by the properties of the fluid, and is subject to failure under high loads (i.e. the liquid can only take so much friction before it breaks down and loses it's valuable properties). In general practice, for performance and cost, viscous LSD's are used, but for high performance, resilience, adjustability and durability, the clutch type LSD is preferable, but has a significantly higher cost.
That's about all I know about LSD's.
It most certainly would melt again after 75C; it's just a hydrogen-bonded organic solid at that point, and hydrogen bonds are weak and only partially-covalent and would easily melt at moderate temperatures.