elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
Shear Thickening Fluid
I want to make some STF by mixing polyethylene glycol and fumed silica. To my dismay, I found the original sample I ordered (Lucas DOT-3 synthetic
brake fluid) is not true polyethylene glycol, but rather some similar stuff. I found an OTC source, MiraLax, but this appears to be a white powder at
room temperature.
So my question to you is, is there a way to make this MiraLax permanently a liquid and still have it remain pure polyethylene glycol? If not, is there
an appropriate substitute to make a decent shear thickening fluid?
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
battoussai114
Hazard to Others
Posts: 235
Registered: 18-2-2015
Member Is Offline
Mood: Not bad.... Not bad.
|
|
GREAT! JUST LOST A BIG PIECE OF TEXT 
What I meant was, I don't know of any established techniques of reducing PEG molecular weight (higher molecular weight PEG is solid and, as it
decreases it becomes liquid). Maybe heat treatment will do, can't say for sure.
Try getting ethylene glycol from anti-freeze and use basic catalysis to get it to polymerize. If you look around it seems the amount of catalyst, and
its type, dictates how high the molecular weight will be. This way you can have some control over the PEG rheology which, I guess, will be important
to get nice results.
|
|
|
elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
I would assume that I want the molecular weight to be as high as possible without becoming solid, to which a cursory glance suggests a MW of about
700.
Of course, I have no idea about basic catalysis. I'm also at a college, with almost no access to equipment. 
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
battoussai114
Hazard to Others
Posts: 235
Registered: 18-2-2015
Member Is Offline
Mood: Not bad.... Not bad.
|
|
But basic catalysis should be easy (I guess), Potassium or Sodium Hydroxide is readily available as drain cleaner and I think its soluble in Ethylene
Glycol, in this case you'd have an homogeneous catalytic process and wouldn't have to worry about dispersion and all that stuff that makes
heterogeneous processes a pain. Just get the drain cleaner, calculate how much will be needed, add to the EG and mix throughly. I'm currently out of
the campus and don't have access to scientific papers, but there is probably some study somewhere about how reaction conditions influence the
molecular weight of the PEG when you use a basic catalyst.
|
|
|
elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
Sounds good. How would I tell the reaction had completed, if it went from a clear liquid to a clear liquid?
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
On second thought, I've decided to use Oobleck instead. Much simpler to make. But now I have a bunch of brake fluid and fumed silica on hand - any
idea what to do with these?
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
battoussai114
Hazard to Others
Posts: 235
Registered: 18-2-2015
Member Is Offline
Mood: Not bad.... Not bad.
|
|
But oobleck can't stop bullets... although silica stf alone can't either, I think they treat high resistance fibers with it.
Fumed silica makes decent sorption column packing depending on its shape. Is it powdered or pellets?
No ideas for the break fluid so far.
|
|
|
elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
Powdered.
I never needed it for bullet resistance, I'd just use UHMWPE for that.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
MrHomeScientist
International Hazard
Posts: 1806
Registered: 24-10-2010
Location: Flerovium
Member Is Offline
Mood: No Mood
|
|
Try it in a silicon thermite! Extremely finely powdered and pure, it should yield some nice Si.
I was going to suggest Oobleck until I saw you found it yourself. It's some crazy stuff. We built a nice little demonstration piece where you can put
it on a large speaker and play different tones through it - one of the weirdest things I've seen!
|
|
|
careysub
International Hazard
Posts: 1339
Registered: 4-8-2014
Location: Coastal Sage Scrub Biome
Member Is Offline
Mood: Lowest quantum state
|
|
Fumed silica is excellent high temperature thermal insulation, about twice as good as perlite which is regarded as a very good insulator:
http://www.diva-portal.org/smash/get/diva2:506266/FULLTEXT01...
[Edited on 8-9-2015 by careysub]
|
|
|
battoussai114
Hazard to Others
Posts: 235
Registered: 18-2-2015
Member Is Offline
Mood: Not bad.... Not bad.
|
|
Powdered won't do for absorption columns. About the brake fluid, toss it in a pyrolysis chamber and make some syngas? Really can't think of anything
interesting.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
