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Topic: Is Electro-active cornstarch slime a Dielectric or Ionic EAP?  (Read 4676 times)

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Offline kyasarin

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Is Electro-active cornstarch slime a Dielectric or Ionic EAP?
« on: January 15, 2008, 12:46:49 AM »
I'm doing a demo in my class on Non-Newtonian fluids.  One of my experiments will be Electro-active cornstarch slime. I believe it is either a Dielectric or Ionic Electroactive Polymer.

This is what I've found on-line:
Dielectric EAPs, in which actuation is caused by electrostatic forces between two electrodes which squeeze the polymer. This kind of EAP is characterized by a large actuation voltage (several thousand volts), but very low electrical power consumption. Dielectric EAPs require no power to keep the actuator at a given position. Examples are electrostrictive polymers and dielectric elastomers.

Ionic EAPs, in which actuation is caused by the displacement of ions inside the polymer. Only a few volts are needed for actuation, but the ionic flow implies a higher electrical power needed for actuation, and energy are needed to keep the actuator at a given position. Examples of ionic EAPS are conductive polymers, ionic polymer-metal composites (IPMCs), and responsive gels. Yet another example is a Bucky gel actuator, which is a polymer-supported layer of polyelectrolyte material consisting of an ionic liquid sandwiched between two electrode layers consisting of a gel of ionic liquid containing single-wall carbon nanotubes. The name refers to bucky balls.

*I'm leaning towards ionic EAPs because "Only a few volts are needed for actuation" and I doubt that the static from the Styrofoam will have a large amount of volts.

Here is the lab: Electro-active cornstarch slime
Mix 3/4 cup (175ml) of cornstarch with 2 cups (475ml) of vegetable oil. Put it into a tumbler in the refrigerator until it is chilled. Remove from the refrigerator, stir to mix (it will have separated), and let warm just enough so that it will flow. Find a block of Styrofoam, about 1by 6 by 6 inches (25x150x150mm - not at all critical), and rub it on your hair (or a wool sweater, or a cat, etc.) to build up a static charge. Tip the container of slime. It should flow slowly. Place the charged Styrofoam just in front of it (an inch or so), in the path of the flow. The slime should stop flowing and seem to solidify. Wiggle the Styrofoam, and the slime will follow it somewhat, and pieces of it may even break off. Remove the Styrofoam, and the flow will resume.

Offline IITian

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Re: Is Electro-active cornstarch slime a Dielectric or Ionic EAP?
« Reply #1 on: January 15, 2008, 11:30:01 AM »
This seems like an interesting demo, but I'm afraid this is not the right place to put this up!

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