The tangled nature of the polymer filaments, with heat-stopping voids indicated as dark blobs (left) and the molecules lining up when drawn and heated into a thin thread (right), compressing the voids, making the material a good conductor (Image: Gang Chen)
Polyethylene is the most widely used polymer in the world, most commonly used for packaging and plastic shopping bags. And like most polymers it is a very good insulators for both heat and electricity. But now an MIT team has developed a new process that causes the polymer to remain an electrical insulator but conduct heat very efficiently in just one direction, unlike metals, which conduct equally well in all directions. This may make the new material especially useful for applications where it is important to draw heat away from an object, such as a computer processor chip.