Sciencemadness Discussion Board

Thixotropic effect

Morgan - 28-12-2010 at 20:49

Long ago I saw a science film about thixotropic substances. The demonstration was that of a black rod perhaps an inch in diameter and about a foot long. The rod/bar was tapped to show it was solid. It was stood on end in a shallow pan and struck with a hammer as you would a large nail. It instantly turned to a black tar-like liquid in the bottom of the pan. Has anyone ever seen this demonstration or have any idea what chemicals might produce this shear stress effect? I have searched the internet far and wide.

TheOrbit - 28-12-2010 at 21:27

google it well and you will find many many examples
http://www.squidoo.com/thixotropy

http://books.google.com/books?id=y0xDUAdQAlkC&pg=PA661&a...

Morgan - 28-12-2010 at 22:09

Thanks TheOrbit,
The second read was good but I am looking for the formula for this particular effect. I recall toying with some guar gum with borax gel I made, and it would reliquify if you shook the jar vigorously. But I was hoping to find an example of a solid unraveling into a liquid if shocked. I guess if you fired an ice cube or say gallium at a wall fast enough, it would go through a change of state. I can't really think of anything room temperature that I've seen that is "frozen" and then liquifies when "shocked" from a rap from of a hammer.
The demonstration appeared to be a black plastic-like solid.

not_important - 29-12-2010 at 10:47

You are talking about anti-thixotropic or shear-thinning substances. Most modern paint, whipped cream, Diutan gum, blood, ketchup are all examples of such.

Ozone - 29-12-2010 at 11:13

Thixotropy is time dependent, shear-thinning (pseudoplastic) is not. Both lead to decreased "viscosity". The opposite, time-dependent thickening, is rheopecty. Mixtures which increase in viscosity with increased rate of shear (see the demonstration video posted above, or cornstarch) are said to be dilatant.

So:

Thinning:

constant shear over time: thixotropic
depends on shear rate: pseudoplastic

Thickening:

constant shear over time: rheopectic
depends on shear rate: dilatant

So, you are actually looking for a pseudoplastic material (unless you can whack it with the hammer, many times, until it reaches flow-viscosity). I know of no material or mixture which fits the bill :(. Even so, the blow would need follow-though to maintain the application of force.

Cheers,

O3

Morgan - 29-12-2010 at 13:12

Regardless of what category you want to put a solid that liquifies when shocked, I was hoping someone had seen this demonstration or have an idea where to look? When I was young and in high school, I read college chemistry demonstration manuals to find the fun stuff. There are a lot/a ton of classic demonstrations on this site to be sure, but not the one I want.
Maybe some obscure soul working for Dow Chemical or something would know. ha
The film I saw on Thixotropy was probably made in the early 70's. It seems like a fun demonstration, why has it been forgotten I wonder? I mean it's a good illustration of another aspect of the nature of matter.
I was thinking when the black cyclinder was struck and liquified into a syrupy tar in the pan, how might it be reconstituted to a solid or "pseudo-solid" again? Would you extrude it under pressure, simply freeze it or treat it with another compound?
I remember once playing with water glass and I put some KMNO4 and maybe some other things it in just playing around. So it solidified into a dark purply plastic glass-like substance and I broke it up and set the beaker with the broken glassy fragments aside. The next day or so it had all joined up again into a smooth hard solid disk. I guess this is straying off-topic, perhaps a very vague analogy, but the only one I could think of. ha

[Edited on 29-12-2010 by Morgan]

[Edited on 29-12-2010 by Morgan]

Morgan - 27-2-2011 at 07:55

A thixotropic effect in the news.
Christchurch Earthquake Showing how the sand liquefies with vibration
http://www.youtube.com/watch?v=tvYKcCS_J7Y

"Some clays are thixotropic, with their behavior of great importance in structural and geotechnical engineering. In earthquake zones, clay-like ground can exhibit characteristics of liquefaction under the shaking of a tremor, greatly affecting earth structures and buildings."
http://en.wikipedia.org/wiki/Thixotropy


[Edited on 27-2-2011 by Morgan]

peach - 27-2-2011 at 08:46

I haven't seen the rod example, but I'm interested enough I'll keep an eye out for it.

There is one that is a lot more common, and produces some strange results. Cornstarch and water (oobleck). If you put some a speaker, and turn it up, you'll see creatures from the swamp crawling up and then reforming in a continuous, spooky way.

The spoog monsters
<iframe sandbox title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/3zoTKXXNQIU" frameborder="0" allowfullscreen></iframe>

Not strictly related, but very pretty in a similar way; ferrofluid on spirals
<iframe sandbox title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/me5Zzm2TXh4" frameborder="0" allowfullscreen></iframe>

Visualising modes of vibration with sand and a plate drive by a speaker; turn your sound volume right down if you don't want a headache
<iframe sandbox title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/YedgubRZva8" frameborder="0" allowfullscreen></iframe>

Morgan - 23-3-2011 at 16:25

I know this isn't a very good example of the solid black rod that liquifies when struck, but it seems to hint at something in that direction, some sort of phase transition.
I bet Bill Nye, Steve Spangler and others would like to present such a demonstration if they had it. It's proving to be quite a challenge. I wish I could find the video I saw. I've looked at one site that has old science films, but to no avail. If you start the video around the 2:50 mark, it cuts to the chase.
http://www.youtube.com/watch?v=8u_SABU_8d0#t=2m50s



[Edited on 24-3-2011 by Morgan]

Morgan - 26-3-2011 at 05:38

Some thoughts on dam breaking.
"Thixotropy is the characteristic of a fluid to form a gelled structure over time when it is not subjected to shearing, and to liquefy when agitated."
Dam Break Wave of Thixotropic Fluid
http://ascelibrary.org/hyo/resource/1/jhend8/v132/i3/p280_s1...

[Edited on 26-3-2011 by Morgan]

Morgan - 29-1-2013 at 18:20

I0. Overall conclusions

"Thixotropy comes about first because of the finite time taken for any shear-induced change in microstructure to take place. The microstructure is brought to a new equilibrium by competition between the processes of tearing apart by stress and flow-induced collision, in a time that can be minutes. Then, when the flow ceases, Brownian motion is able to move the elements of the microstructure around slowly to more favourable positions and rebuild the structure. This can take many hours to complete. The whole process is completely reversible."

"The position of various areas of thixotropy today is well summarised by three quotations:"
(1) As to the proper understanding of the word itself, we can do no better than quote from Lewis Carroll's Alice in Wonderland, "When I use a word," Humpty Dumpty said ... "it means just what I choose it to mean--neither more nor less". "The question is", said Alice, "whether you can make so many words mean so many different things".
(2) As to the state of experimental investigation in thixotropy, we quote Godfrey [4],
"Thixotropy is one of the more complex characteristics associated with the behaviour of non-Newtonian liquids ... most of the available [experimental] data leave something to be
desired".
http://www.dfi.uchile.cl/~rsoto/docencia/FluidosNoNewton2008...

Morgan - 4-2-2013 at 18:50

House of Cards
http://www.laviosa.it/index.php?thickening-thixotropic-prope...

June 11, 1936
"Thixotropy was first formally observed in iron oxide sols ..."
http://pubs.acs.org/doi/abs/10.1021/j150378a008

arsphenamine - 4-2-2013 at 19:33

Honey.

Morgan - 5-2-2013 at 12:26

I was thinking about the demonstration I saw with the solid black rod that was tapped on the desk to show it was solid, like holding a 25cm long wooden dowel in your hand. Then being stood on end and struck with a hammer, it transitions to a black syrupy liquid.
So maybe ferric oxide was one of the ingredients, and there are some references of carbon black and silicon carbide whiskers being used in thixotropic formulas. Mixed metal hydroxides might be another possibility.
http://books.google.com/books?id=wu48AAAAIAAJ&pg=PA444&a...

Thixotropic cement compositions
http://www.google.com/patents/US4822421

"Similarities in particle size and shape, though oppositely charged, and rheology between the two systems provide indirect evidence of similar rebuilding mechanism, so it is assumed that, for positively charged MMH suspension, long-range electrostatic double layers forces lead to the formation of a solid-like structure."
http://sioc-journal.cn/Jwk_hxxb/EN/abstract/abstract336730.s...

"electrostatic interactions between clay and MMH particles ..."
http://books.google.com/books?id=y0xDUAdQAlkC&pg=PA677&a...

Heather honey
"Close up of the plastic needles. There are 1.700 of them, one for every cell in the comb. Each one is supported by a spring so it will not brake when there is pollen in the cell."
http://beeman.se/biodling/ljung/ling-2-nf.htm

"The name “Calluna vulgaris” originates from the fact that brooms were popularly made from heather. Calluna is old Greek for “to sweep”, vulgaris means “common.”
http://www.honeytraveler.com/single-flower-honey/heather-hon...


http://en.wikipedia.org/wiki/Micelle
http://journalofrheology.org/resource/1/jorhd2/v46/i6/p1445_...

Morgan - 15-2-2013 at 17:16

The-THIXOTROPIC-Nature of-SILT
http://www.youtube.com/watch?v=-i0QW-Zrd4Y

Morgan - 16-2-2013 at 08:54

Fun facts
"There is a huge variation in the chemistries of bentonites, it is impossible to specify an average (bentonite is not employed in ceramics for its chemistry). Any generic chemical analysis is thus only an attempt to represent the amounts you might find in a common variety. Because of the high iron content, bentonite is considered a dirty material and thus the tug-of-war between the valuable working properties it imparts and the need for whiteness or pure color that it impedes."

"Fine particle size: Bentonite is colloidal (particles are so small the action of water molecules is enough to keep them in suspension). It is typically 10 times finer than ball clay. It can have a surface area of almost 1000 square meters per gram (50 times that of kaolin, 5000 times that of silica flour)."

"Suspension: Bentonite is used to keep particulates in suspension in all sorts of consumer and industrial products, and in glazes in ceramics. The mechanism is charge attraction, that is, opposite electrolytic charges develop on the surfaces and edges of dispersed particles and give rise to a stable 'house-of-cards" structure that can be disrupted by shear stress. However when the stress is removed, the structure re-establishes itself."
http://digitalfire.com/4sight/material/bentonite_106.html

In case you understandably fell asleep in the previous video before the end, there's this curious sword in the stone quality I thought worth seeing, oddly illustrated by a child.
http://www.youtube.com/watch?v=-i0QW-Zrd4Y#t=10m28s

[Edited on 16-2-2013 by Morgan]

Morgan - 16-2-2013 at 16:12

The wind makes for a very bad recording the first minute but the sound quality gets better in parts, you hear him mention "thixotropia" to the students.
"And so you can die ..."
Dancing samba in quicksands of St. Michel's Bay
http://www.youtube.com/watch?v=827Aw2jIvrU

Morgan - 14-8-2013 at 08:22

Tidbits on guar if you can get by the presentation.
Guar: The obscure bean worth a bundle - Decoder
http://www.youtube.com/watch?v=Pwibi9_lPQI

Morgan - 25-12-2014 at 16:48

Some more tidbits.

quick clay - Geotechnical Engineering
https://www.youtube.com/watch?v=LgDQsYAcS3o

quick clay
https://www.youtube.com/watch?v=uvsWQd-AWEE

"These landslides are retrogressive, meaning they usually start at a river, and progress upwards at slow walking speed. They have been known to penetrate kilometers inland, and consume everything in their path."
http://en.wikipedia.org/wiki/Quick_clay

"The mechanics of a Leda clay landslide almost defy imagination: the soil beneath the ground's weathered crust can suddenly run like water, carrying earthen slabs, rocks, trees and houses at terrific speed. The landslide can feed upon itself. Leda clay is so sensitive that the initial slide can trigger a progressive series of failures in the clay belt that can consume acres of flat land behind the original collapse."
"Leda clay," says Ms. Aylsworth, "is a really fascinating substance -- it's quite unique -- but it can also be deadly."
The bizarre mechanics of a Leda clay landslide
http://www.canada.com/ottawacitizen/news/story.html?id=31177...

I liked how the dynamite turning the clay to liquid too.
The Quick Clay Landslide at Rissa - 1978 (English commentary)
https://www.youtube.com/watch?v=3q-qfNlEP4A

Another scenario not involving salt leaching.
"Removal of an electrolyte by natural leaching with fresh water appears to render the clay unstable. When the clay structure undergoes collapse, flowage is believed to result."
"Field conditions suggest that flowage of non-marine quick clay may be attributed to the action of a dispersant such as humic acid."
http://gsabulletin.gsapubs.org/content/76/8/853


[Edited on 26-12-2014 by Morgan]

Morgan - 12-7-2017 at 05:39

A novel methodology to regain sensitivity of quick clay in a geotechnical centrifuge

"These clays behave like a liquid after remoulding, due to the loss of structure and the high water content. This change of material structure during remoulding is irreversible. Therefore, a special reconstitution method is required if sensitivity is to be regained. Only very few researchers have tried to reconstitute sensitive clays."

"Although very weak compared to the undisturbed natural
material, the reconstituted material meets the Swedish definition of quick clay. However, the developed method still needs to be optimized and validated for other quick clays. Although, besides the influence of salinity, water content and consolidation, no comprehensive testing programme is adopted to systematically find the optimal conditions, the results are promising for further research."

http://publications.lib.chalmers.se/records/fulltext/186210/...

STUDIES ON THE PROPERTIES AND
FORMATION OF QUICK CLAYS

"There are two main reasons for the occurrence of a high sensitivity, namely a reversible effect, thixotropy, and an irreversible
condition, known as quickness. A quick clay is defined as a clay that when undisturbed has a certain shear strength and can be regarded as a solid body, but which when remolded can be regarded as a liquid. In practice, a clay is called "quick" when its sensitivity exceeds a certain number, usually 30-50, depending on the method used for the determination of the shear strength."

"In a thixotropic system, the particles and the water--at rest after
remolding--become reorientated in a new state of equilibrium. During
this process, the changed stresses in the solid phase must attain new values, which give rise to stresses in the liquid phase which appear in the form of suctions. This indicates a regain in strength, thixotropy, dependent on the orientation of the particles and the water. This regrouping is a time-consuming process, which the author regards as a coagulation process. It could be said that the greater the cohesion in the clay, in a certain range of water content, the greater, usually, is the strength regain."

"Further, attempts made to produce quick clays by leaching certain natural salt clays were, in general, not successful."

http://www.clays.org/journal/archive/volume%2012/12-1-87.pdf



[Edited on 12-7-2017 by Morgan]

DrP - 12-7-2017 at 07:07

I don't think it has been mentioned, but at schools here when we were younger we were first introduced to thixotropy with the example of ketchup. It won't come out when you try to pour it out.... but when you bash it, all of a sudden, WAY too much comes out at once in a torrent.

Maybe (I would assume) modern formulations of the stuff aren't so bad... maybe they aren't so thixotropic... or maybe it's the new squeezy bottles that get around the problem, but it isn't as much of an issue as it used to be.

Morgan - 14-7-2017 at 08:20

I was tinkering with some calcium bentonite clay from Death Valley and read in a journal that adding sodium carbonate could partially revert it to a sodium bentonite, what I want, which is thixotropic. So then I wondered if maybe NaOH would work and came across this. As an aside, my calcium bentonite is very slippery when wet, almost like oil.

"Even if one attempts to exchange the calcium ions for sodium ions by the use of sodium hydroxide a truly thixotropic system is not obtainable, because not all the calcium ions can be replaced with sodium ions."

"It has been observed that all sodium bentonites and hectorite exhibit
pronounced thixotropic properties. In the case of calcium bentonites a
drastic difference in their behavior is immediately observed when they are
placed in water; they do not have the tendency to swell to any appreciable
extent but will instead settle out fairly fast. It can be proved that the
calcium ions cannot be considered as part of the actual lattice because
they can be exchanged. This can be accomplished by treating the calcium
bentonites with a high concentration of sodiuln salts and then washing
them carefully. The net result is then a sodium clay which, however, will
not exhibit thixotropy comparable with that of the original sodium bentonites and heetorites."


Anyway I ordered some sodium bentonite clay from Wyoming for the heck of it just to see what it does.

And I've some white kaolin which is something like this "Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6) octahedra."
https://en.wikipedia.org/wiki/Kaolinite

"It is known from experiment that to obtain the maximum gelation
effects in electrocratie colloidal systems, monovalent ions possessing a
sign opposite in charge to that of the sol are most suitable. A negatively
charged bentonite will set to a gel by the use of lithium, sodium, potassium, hydrogen, etc., and it is important to note that the effectiveness of adsorption of the ion in the diffuse layer increases from lithium to hydrogen in the Hofmeister series. This indicates that the less strongly the ion carrying the charge opposite to that of the sol particle is adsorbed in the diffuse layer, the more powerful it is in forming gels."
https://en.wikipedia.org/wiki/Hofmeister_series

"All montmorillonites and bentonites have the basic structural pattern of
mica, namely, two silica sheets which enclose an alumina sheet. One of
the most important factors is that the spacing between the lattice units
varies with the moisture content in the case of sodium bentonites. This
is the reason why they are frequently referred to as the "expanding
lattice" group; this group comprises four main minerals, bentonite,
saponite, beidellite, and nontronite. In the clay mineral hectorite, almninum has been largely replaced by magnesium."


"Regarding the formation of these minerals we believe that silica and
alumina gels must first react, and then condense to form the specific
minerals. Clays owe their genesis to the presence of silica and alumina
or magnesia gels and to the changes they undergo with time or temperature.
Recent studies on the formation of clay minerals have offered proof
of the validity of this theory (Hauser, 1952)."
COLLOID SCIENCE OF MONTMORILLONITES AND BENTONITES
http://www.clays.org/journal/archive/volume%202/2-1-439.pdf

Tidbits
"Bentonite is used in drilling fluids to lubricate and cool the cutting tools, to remove cuttings, and to help prevent blowouts."

"Most often, bentonite suspensions are also thixotropic, although rare cases of rheopectic behavior have also been reported. At high enough concentrations (about 60 grams of bentonite per litre of suspension), bentonite suspensions begin to take on the characteristics of a gel (a fluid with a minimum yield strength required to make it move). So, it is a common component of drilling mud used to curtail drilling fluid invasion by its propensity for aiding in the formation of mud cake."
https://en.wikipedia.org/wiki/Bentonite

Morgan - 14-7-2017 at 18:16

Quote: Originally posted by DrP  
I don't think it has been mentioned, but at schools here when we were younger we were first introduced to thixotropy with the example of ketchup. It won't come out when you try to pour it out.... but when you bash it, all of a sudden, WAY too much comes out at once in a torrent.

Maybe (I would assume) modern formulations of the stuff aren't so bad... maybe they aren't so thixotropic... or maybe it's the new squeezy bottles that get around the problem, but it isn't as much of an issue as it used to be.


I recall mixing up some guar gum and borax in a glass peanut butter jar with the label removed. It gelled into a solid green piston (food coloring added) and I could sling this slug of gum back and forth vigorously in the half filled jar, slapping the lid and bottom repeatedly until finally it would break and turn into a syrupy liquid. It would reset itself over time and you could do it again and again. After a few days or so the effect gave out for some reason and it was just a syrupy liquid all the time.
Gums are used in ketchup too. One note about the guar gum in the jar experiment, over time the gum either starts to possibly rot(?) or break down and one day I unscrewed the lid and it had built up an extreme amount of air pressure. Had I not the jar may have one day exploded.

Comparative studies of xanthan, guar and tragacanth gums on stability and rheological properties of fresh and stored ketchup
"Xanthan gum created the most overall texture acceptability, structure strength and links strength approximately in both fresh and stored samples in lower concentration than Guar gum and Tragacanth gum. While Xanthan gum or Guar gum created thixotropic behavior, sample containing Tragacanth gum exhibited rheopectic behavior. As concentration of Tragacanth gum was increased, a decrease occurred in rheopectic behavior. In level of 0.25 %, Xanthan gum was better than two other gums in stability, overall texture acceptability, yield stress, structure strength, spreadability, links strength in fresh and stored samples and retaining of thixotropic behavior at the end of storage, while Tragacanth gum created greater viscosity at shear rate of 500 than other two gums in fresh and stored samples that could be related to thermodynamic incompatibility between starch and this gum."
https://link.springer.com/article/10.1007/s13197-015-1837-9

http://www.foodnavigator.com/Science/Guar-replacers-target-b...

"Guar gum is economical because it has almost eight times the water-thickening potency of cornstarch - only a very small quantity is needed for producing sufficient viscosity. Thus, it can be used in various multiphase formulations: as an emulsifier because it helps to prevent oil droplets from coalescing, and/or as a stabilizer because it helps to prevent solid particles from settling. Guar gum is a viscosifier with very favorable rheological [clarification needed] properties. It has a really useful ability to form breakable gels when cross-linked with boron. This makes it extremely valuable for hydraulic fracturing."
https://en.wikipedia.org/wiki/Guar_gum

[Edited on 15-7-2017 by Morgan]

Morgan - 14-7-2017 at 18:36

Recalling the recent overturned truck hagfish slime event I began to wonder if that too might be capable of becoming thixotropic.
At the scene of the slime, hagfish clean-up continues along U.S. 101
http://www.oregonlive.com/pacific-northwest-news/index.ssf/2...

"Isolation of Soluble Protein from Slime Secretion--Several hagfish
were stimulated electrically and the drops of secretion washed
down with distilled water, producing a concentrated slime, which
was filtered on a Buchner funnel. The filtrate, acidified with
acetic acid, formed a thixotropic gel."
http://www.jbc.org/content/138/1/263.full.pdf

Hagfish drilling fluid?
https://books.google.com/books?id=bPyjBwAAQBAJ&pg=PA23&a...

Fun fact videos
https://www.youtube.com/watch?v=Bb2EOP3ohnE
https://www.youtube.com/watch?v=t5PGZRxhAyU