thixotropy
1. A phenomenon exhibited by various gels, in
which the system displays the mechanical
properties of a gel when undisturbed, but becomes
a liquid when mechanically agitated and again
becomes a gel when allowed to stand. This
"reduction in viscosity" is due to a temporary
breaking down of an internal structure of a system
under shear. The viscosity of thixotropic systems
depends on the "shear history," i.e., the extent
of previous mechanical agitation to which the
material has been subjected. The property is
important in paper coating colors because it
allows the mixing of color formulation to a
viscosity which permits the color to be applied
and allows surface leveling due to after flow of
the color on the material. 2. A property of
adhesive systems which causes them to thin upon
isothermal agitation and thicken when allowed to
stand. (17 , 309 )
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