Talk-Polywell.org

Spider silk conducts heat as well as metals, study finds

Thermally-conductive electrical insulation?

Diamond is a pretty good thermal conductor and electrical insulator. But rather expensive for many jobs. I hear synthetic sapphire is used for the job mounting LED dies.

If a flexible form of diamond can be produced, great.

Brittle glass can be melted, extruded into flexible fibers and woven into cloth.

Maybe a 1-D CVD process can be found to make flexible diamond fibers. That would make a very cool fabric.

The troubles with asbestos come to mind, however...

I've downloaded a couple of papers on the method used to measure this phenomenon, and may try to do it myself. This sounds fascinating.

Now, let's see, where can I find a garden spider? We used to have one spinning webs on the house every spring. Ours would take the web in every evening and spin a new one in the morning, so it probably does little harm to harvest a web in the evening.

For those interested in the nitty-gritty of the technique, I found a paper on-line under the file name adma_201104668_sm_suppl.pdf. The method is intended for thin conductive wires and involves stretching a wire between two good heat sinks. The wire is self-heated by a DC current, and temperature change is evaluated by the resistance change. To test spider silk, they sputter-coat on about 10 nm of gold (the apparatus for this is common in electron microscope labs, and the paper reports using SEM on samples of spider silk). Sputter-coating can be rigged by any fusion experimenter with a modest vacuum system. The test is done in a vacuum, somewhat better than my present capability, but I was hoping to go turbo anyway. They aim for < 1 millitorr (below the range where thermocouple gages work and so below significant convective heat loss).

The electronic apparatus involved seems to be a fast-switched current source and a digital oscilloscope. Type T thermocouples (suitable for vacuum and good at near-ambient) are used for temperature measurements of the heat sinks.

I'm wondering if my thermal imager can see something this thin. Mine is not intended for close focussing, but I think there are models that work on microscopes. If so, this test might also be done by viewing thermal gradients directly. I'm also interested in using a fine thermocouple as a heat flow gage, allowing direct measurement of heat flow down a filament.