I've been reading some side information on materials for a class I'm taking for work, and I brainstormed a question.
I know there are materials that change shape depending on if there's an electric charge (the name for these materials escapes me, can someone help me out?), and I am curious if there is a similar cloth-like material that allows for a variable porosity? If there is, could anyone share a link. And if there isn't, does this idea seam feasible?
Materials that change shape according to electric charge are known as piezoelectrics. In general materials that undergo change from external stimuli are called Smart Materials. It seems that this forum doesn't allow me to post links, so checkout wikipedia and google.
I'm not so sure about porosity though. In the traditional ceramics industries, they use refractories that decrease porosity with the increase of temperature. That's all I can think of.
Hope this helps.
I'm not so sure about porosity though. In the traditional ceramics industries, they use refractories that decrease porosity with the increase of temperature. That's all I can think of.
Hope this helps.
Ferroelectric materials behave as piezoelectric ones do, but more efficiently, once they have been polarized. More interesting for a cloth, as I expect PVDF to be easily spun and woven - though it is uncommon. More comfortable than a ceramic, probably.
I have read for less than 6 months that some manufacturer of military batteries had made a material with controllable porosity - to separate electrodes from the electrolyte and unite them when needed? Forgotten who, where, when, and worse, how. It was discussed on this forum. Have a look at MIT's Technology Review also?
If you can choose the liquid, the answer is definitely yes. They are called ferrofluids - and an electric equivalent exists - and get some stiffness if you apply a magnetic field, because this aligns the magnetic particles they contain. Used to actively adjust the effectiveness of car dampers.
Apart from piezo- and ferroelectricity, whose effect is small, you may consider shape memory alloys http://en.wikipedia.org/wiki/Shape_memory . Parts made from them take one from two shapes depending on the temperature. If you want to make active clothes that regulate the skin temperature, maybe. But they are metals.
Maybe you can tell more? Porous to which gas or fluid, at what temperature, how much porous, what kind of control power you have?
I have read for less than 6 months that some manufacturer of military batteries had made a material with controllable porosity - to separate electrodes from the electrolyte and unite them when needed? Forgotten who, where, when, and worse, how. It was discussed on this forum. Have a look at MIT's Technology Review also?
If you can choose the liquid, the answer is definitely yes. They are called ferrofluids - and an electric equivalent exists - and get some stiffness if you apply a magnetic field, because this aligns the magnetic particles they contain. Used to actively adjust the effectiveness of car dampers.
Apart from piezo- and ferroelectricity, whose effect is small, you may consider shape memory alloys http://en.wikipedia.org/wiki/Shape_memory . Parts made from them take one from two shapes depending on the temperature. If you want to make active clothes that regulate the skin temperature, maybe. But they are metals.
Maybe you can tell more? Porous to which gas or fluid, at what temperature, how much porous, what kind of control power you have?