Re: Reverse Electrorheological Material?


<degroof@xxxxxxxxx> a écrit dans le message de news:
1115426150.547876.173820@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Are there any materials that act in a manner opposite to
electrorheological materials? (i.e. are normally solid or semi-solid but
liquify when subjected to
> an electric field)

Hi,

I'm a polymerist a have therefore a little knowledge in rheology, but in
fact, I have few regarding the effects of electric field on the rheological
behaviour of materials.

Anyway, may I leave you my opinions. Such materials that increase viscosity
upon mechanical stress are well-known and called dilatants or shear
thickening materials. A good example for this is wet sand, but this kind of
behaviour is also often found in highly concentrated suspensions, where
solid particles are mixed with a little plasticizer or resin. At low shear
or at rest, the materials behaves like a liquid because the liquid perfectly
wets the solid particles, which can move easily from one another. But at
higher shear, the liquid no longer wets the particles, which interact
strongly and the material look as if it is viscous.
I don't know whether these materials can also increase viscosity under an
electric field, but I suppose so. If one can make these particles to
interact, I presume that the material will behave this way. The question is
: are the particles as sensitive to electric field as they are to mechanical
stress ? And for that, I suppose that it strongly depends on the nature of
your particle, maybe their zeta potential, and also the nature of the
medium.
Maybe can I suggest that you post a question in the following newsgroup,
dedicated to polymers : sci.polymers

Hope this will help.
Best regards.

Nicolas DELFAU
delfau@xxxxxxxxxx


.

Relevant Pages

  • Re: Battery breakthrough
    ... > electrode. ... batteries involving high energy materials that are only stable because ... Nanocrystalline matterials have small particles therefeore more ... only a fractioni of full intercalation ...
    (sci.energy)
  • Re: Battery breakthrough
    ... > batteries involving high energy materials that are only stable because ... > contact area between particles. ... I once read about carbon nanotubes being mixed in with photovoltaic ... only a fractioni of full intercalation ...
    (sci.energy)
  • Re: Physics of Settling?
    ... where stiffness isn't part ... That's the basis for 'photonic bandgap materials' in that there are certain directions that light can no longer propagate, ... If you then dope the material with fluorescent particles, you can affect the excitation lifetime. ... It's easier to think of materials to make than to predict what the macroscopic properties will be. ...
    (sci.physics)
  • Re: Little dirt in the engine.
    ... Like Jeff says, if they are non-metal or other "hard" materials, such as ... plastic, and are not in the piston chambers, a simple run of engine will ... the new build to get out metal shavings and the particles you describe. ...
    (rec.autos.tech)
  • Re: Color darker when wet
    ... I'm talking about all materials that absorb water! ... In all cases one drop of liquid changed the ... If I take a piece of paper and wet it ...
    (sci.physics)