MIT Scientists Make a Polyethylene Heatsink 153
arcticstoat calls our attention to MIT research that has produced a version of polyethylene that can conduct heat away from computer chips. Polyethylene is the most widely used plastic. It's not clear how practical this research is for industrial-scale use, involving as it does an atomic-force microscope. The work is detailed in a paper published in Nature Nanotechnology this month. "The new process causes the polymer to conduct heat very efficiently in just one direction, unlike metals, which conduct equally well in all directions. ... The key to the transformation was getting all the polymer molecules to line up the same way, rather than forming a chaotic tangled mass, as they normally do. The team did that by slowly drawing a polyethylene fiber out of a solution, using the finely controllable cantilever of an atomic-force microscope, which they also used to measure the properties of the resulting fiber. This fiber was about 300 times more thermally conductive than normal polyethylene along the direction of the individual fibers, says the team’s leader..."
Article is wrong. (Score:5, Interesting)
Before anyone asks, the article is clearly wrong in the statement "The new process causes the polymer to conduct heat very efficiently in just one direction...", the heat moves along one dimensions, in 2 directions.
Re:Maxwell demon (Score:2, Interesting)
Is it a crystal polymer? (Score:4, Interesting)
If all polymer molecule strings are all oriented the same, is it a crystal?
This setup may show interesting optical properties as well. It's amazing research really, with processing matter at that atomic scale control. Being able to buildup matter that precisely will reveal all new dreamed uses. I really hope this will go forward as discovering industrial processes of controlling matter buildup arrangement at an atomic scale in mass-production.
Could Help Cheapen Up Spacecraft (Score:5, Interesting)
The single dimension (not direction) transfer mechanism could also be very useful. If you can ensure that heat will move along only a single axis, you have a bit more freedom in placing sensitive components in and around your conduction paths within your spacecraft. All in all, this could be a really useful material, if it can ever be scaled up for use in industrial applications. Here's hoping.
*crosses fingers*
Re:Dimension, Not Direction (Score:3, Interesting)
Re:Article is wrong. (Score:4, Interesting)
Re:Article is wrong. (Score:3, Interesting)
You connect a heat source to the bottom of a water tank, as it heats water on the bottom, the density of water in vicinity decreases and flow upward in one direction.
Yes because that's also the direction of the heat gradient vector. Put a refrigerator at the bottom, and you'll soon find that the transfer of heat is now reversed.
If heat could only transfer from the bottom of the tank to the top, and if the top of the tank was much hotter than the bottom but heat was not transfered to the bottom, then that would be transferring heat in one direction, in the sense meant by the GP, and would violate thermodynamics.
Re:Article is wrong. (Score:2, Interesting)
Thermal bias != Maxwell's Demon.
The second law does not require that heat flow from hot to cold, only that there is a net increase in heat. Obviously this requires an external energy source, though. And the water example is not a thermal bias, no, but it is a neat case. The water actually DOES transmit heat through a vertical column much faster in an upward direction via convection, than cooling (which is only aided by convection under 4C, which is an inflection point in the T/D curve for water). In steady state the water will approach thermal equilibrium, but the rate at which equilibrium is reached is vastly different depending on the direction of the thermal gradient.