World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0000817680
Reproduction Date:

Title: Thixotropy  
Author: World Heritage Encyclopedia
Language: English
Subject: Shear thinning, Creaming (chemistry), Geotechnical engineering, Non-Newtonian fluid, Soil mechanics
Collection: Continuum Mechanics, Fluid Dynamics, Non-Newtonian Fluids, Soil Mechanics, Soil Physics
Publisher: World Heritage Encyclopedia


Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick (viscous) under static conditions will flow (become thin, less viscous) over time when shaken, agitated, or otherwise stressed (time dependent viscosity). They then take a fixed time to return to a more viscous state. In more technical language: some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a step change in shear rate. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids. Others such as yogurt take much longer and can become nearly solid. Many gels and colloids are thixotropic materials, exhibiting a stable form at rest but becoming fluid when agitated.

Some fluids are anti-thixotropic: constant shear stress for a time causes an increase in viscosity or even solidification. Constant shear stress can be applied by shaking or mixing. Fluids which exhibit this property are usually called rheopectic. They are much less common.


  • Natural examples 1
  • Applications 2
  • Etymology 3
  • See also 4
  • References 5
  • External links 6

Natural examples

Some clays are thixotropic, with their behavior of great importance in structural and geotechnical engineering. Landslides, such as those common in the cliffs around Lyme Regis, Dorset and in the Aberfan spoil tip disaster in Wales are evidence of this phenomenon. Similarly, a lahar is a mass of earth liquefied by a volcanic event, which rapidly solidifies once coming to rest.

Drilling muds used in geotechnical applications can be thixotropic. Honey from honey bees may also exhibit this property under certain conditions (such as heather honey or mānuka honey).

Another example of a thixotropic fluid is the synovial fluid found in joints between some bones. Both cytoplasm and the ground substance in the human body is thixotropic, as is semen.[1]

Some clay deposits found in the process of exploring caves exhibit thixotropism: an initially solid-seeming mudbank will turn soupy and yield up moisture when dug into or otherwise disturbed. These clays were deposited in the past by low-velocity streams which tend to deposit fine-grained sediment.

A thixotropic fluid is best visualised by an oar blade embedded in mud. Pressure on the oar often results in a highly viscous (more solid) thixotropic mud on the high pressure side of the blade, and low viscosity (very fluid) thixotropic mud on the low pressure side of the oar blade. Flow from the high pressure side to the low pressure side of the oar blade is non-Newtonian. (i.e.: fluid velocity is not proportional to the square root of the pressure differential over the oar blade).


Many kinds of paints and inks— e.g.plastisols used in silkscreen textile printing— exhibit thixotropic qualities. In many cases it is desirable for the fluid to flow sufficiently to form a uniform layer, then to resist further flow, thereby preventing sagging on a vertical surface. Some other inks, such as those used in CMYK-type process printing, are designed to regain viscosity even faster, once they are applied, in order to protect the structure of the dots for accurate color reproduction.

Solder pastes used in electronics manufacturing printing processes are thixotropic.

Thread-locking fluid is a thixotropic adhesive that cures anaerobically.

Thixotropy has been proposed as a scientific explanation of blood liquefaction miracles such as that of Saint Januarius in Naples.[2]

Semi-solid casting processes such as thixomoulding use the thixotropic property of some alloys (mostly light metals) (bismuth). Within certain temperature ranges, with appropriate preparation, an alloy can be put into a semi-solid state, which can be injected with less shrinkage and better overall properties than by normal injection molding.


The word comes from Ancient Greek θίξις thixis "touch" (from thinganein "to touch") and -tropy, -tropous, from Ancient Greek -τρόπος -tropos "of turning", from τρόπος tropos "a turn", from τρέπειν trepein, "to turn". It was invented by Herbert Freundlich originally for a sol-gel transformation.[3]

See also


  1. ^ Hendrickson, T: "Massage for Orthopedic Conditions", page 9. Lippincott Williams & Wilkins, 2003.
  2. ^ .2, (1994:123)30 Chemistry in BritainGarlaschelli, Ramaccini, Della Sala, "The Blood of St. Januarius",
  3. ^ Reiner, M., & Scott Blair, G. W., (1967) in Eich, F. R., (ed) Rheology, Theory and Applications Vol 4 p 465 (Academic Press, NY)
  • Derakhshandeh, B. Vlassopolous D., and Hatzikiriakos S.G., Thixotropy, Yielding and ultrasonic Doppler velocimetry in pulp fibre suspensions, in Rheologica Acta DOI 10.1007/s00397-011-0577-7, 2011)
  • Dam break wave of thixotropic fluid in Journal Hydraulic Engineering, 2006, Vol. 132, No. 3, pp. 280–293

External links

  • The dictionary definition of thixotropy at Wiktionary
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.