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Thread: Electrically variable viscosity??

  1. #1 Electrically variable viscosity?? 
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    Hello,
    I am considering creating a product that would need a liquid that could be rigid at one moment and then other varying degress of viscosity as a result of some input (I'm thinking electric).

    Do any inexpensive compounds exist that have this property? The current products I can think of as an example are some higher end luxury and sports cars that have variable suspension systems. Please forgive my appalling lack of chemical knowledge and probable abuse of these chemical terms, but I hope you can see through this fog to my question.

    Thankyou!
    Paul


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  3. #2  
    Forum Ph.D. william's Avatar
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    Hi Paul,
    I do not know the answer to your specific question but have you thought about varying the viscosity via temperature? Maybe there is a mechanism that can vary the temperature to your required specifications...? That was my first thought.

    Cheers,
    william


    "... the polhode rolls without slipping on the herpolhode lying in the invariable plane."
    ~Footnote in Goldstein's Mechanics, 3rd ed. p. 202
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  4. #3  
    Universal Mind John Galt's Avatar
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    You may be looking for a liquid that is thixotropic: its apparent viscosity varies with the shear rate. At low shear rates the viscosity is extremely high, in extreme cases effectively solid, but at high shear rates the apparent viscosity is low.
    Such fluids are obviously non-Newtonian in character. Their flow properties are approximated by a model developed by the Victorian sewage engineer Bingham. They are known as Bingham plastic fluids.
    There might be something you could search on there.
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  5. #4  
    Forum Freshman César's Avatar
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    Paul,

    first things first. What you describe has a name: electrorheological fluid. If you google it you will find a lot of information, from how to electrically control it to different products that present the characteristic.

    I understand what you say about exotic compounds like lithium polymethacrylate (google it) or strontium titanate suspended in silicone. An unexpensive alternative is milk chocolate http://www.findarticles.com/p/articl..._18974509/pg_1 .

    Regarding measurement of viscosity for this fluids, even though Re can always be calculated if they are moving, the adimensional number to consider is Mason number. The effect of changing viscosity by the application of electric or magnetic fields is called the Winslow effect.

    Best regards,

    César
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  6. #5  
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    Thankyou very much for those excellent leads!!!
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