Shear Thickening Fluid - Hammer Impact

This video displays the instantaneous increase in viscosity as the hammer strikes the fluid. The hammer impact is very quick, but if you look closely you'll see it. At the 6 second mark, a shadow obscures the indentation.

The simple explanation:
This substance displays four different properties on four different time scales. At very long timescales, it behaves like a liquid spreading out onto a flat surface. At moderate timescales, the substance stretches like a plastic solid. At short timescales, it bounces like an elastic solid. And, at very short timescales (the impact of a high-speed projectile), the substance simply shatters.

This substance is a dilatant compound, which means it becomes solid under the influence of pressure. If you've ever played with Oobleck or Smart Mass Putty, you've experienced the same properties.

The complicated explanation:
Some of the behaviors listed above are an example of a dilatant compound, where the viscosity (i.e. the resistance to flow) increases faster than the strain rate. Although not common, some materials do exhibit dilatant behavior (concentrated aqueous corn starch suspensions -- read: Oobleck).

However on its own, this is not enough to explain the behavior of this substance. In fact there are two mechanisms (and hence two characteristic time scales) at work.

The high molecular weight of the primary ingredient PDMS (Poly Dimethyl Siloxane) has a characteristic polymeric relaxation time, defined by the time that a random walk allows the chain to relax from a stretched state through thermal vibrations.

However due to the Boric acid (the fourth ingredient by weight), there are also transient Boron mediated crosslinks arising from associating Boron linkages. These act to give the substance a behavior more like an elastic solid than a liquid.

However since these crosslinks are dynamic, the material is not permanently locked in place and can consequently flow under the correct conditions. Therefore at longer time scales, the substance behaves like a high molecular weight polymeric fluid.

Over very short time scales the putty behaves like a crosslinked elastic solid, shattering like a ceramic on impact.

View my other videos for a demonstration of all four behaviors.

Source: http://www.thinkgeek.com

Category:

Science & Technology

Tags:

• Shear
• Thickening
• Fluid
• STF
• dilatant
• compound

[EnigmaZR]

I have updated the description for this video. Please refer to it if you have any questions.

[BatmanTheSmiter]

thinkgeek [dot] com [slash] geektoys [slash] cubegoodies [slash] 5ac8 [slash] detail

You LITERALLY took the description from the Smart Mass ThinkGeek page. All you did to "make it your own" was omit any time they said Smart Mass in the text. Way to be creative...

[EnigmaZR]

Your Bat senses serve you well. Too bad echolocation didn't point out the thinkgeek citation at the end of the description. Better luck next time...

[attackblow]

that doent look like much of a fliud it looks like a piece from the black suit in spider man

[Madelineblooddoll]

You people are too stupid to understand how useful this could be when applied to the right "project"

[SisAndBroProCo2nd]

Like if you thought of crona's black blood.

[theraVen27]

@maakjar

such as what?

what use does silly puddy with metal shavings have???

[maakjar]

This is a great product I hope it finds some practical uses on the market

[eclipse245]

Lol thumbs up if you had to watch it twice to even see the hammer hit :P

[ILykToDoDuhDrifting]

omg it's d3o!

[MrBracey100]

Non newtonian liquids are fun!

[MegaPanda9000]

dumb video

[LeeesesPieces]

Why did you not just do a second "take" without someone standing exactly to block the light that would've allowed this demonstration to be VISIBLE? Really strange and pointless upload.

[johnclavis]

I admire your charitable impulses in hiring blind people to do the lighting and camerawork... but do you think you could restrict your YouTube video uploads to things that can actually be *seen*?