Ja. Horn et Br. Patterson, THERMALLY-INDUCED REVERSIBLE COAGULATION IN CERAMIC POWDER POLYMER LIQUID SUSPENSIONS, Journal of the American Ceramic Society, 80(7), 1997, pp. 1789-1797
It was observed that slurries of oxide powders in oxidized polybutene
fluids Can be caused to change reversibly between fluid, nearly Newton
ian behavior and plastic behavior by modest changes in temperature, Th
is phenomenon was believed to result from changes in the dispersion vs
association among the particles, The rheological effects of temperatu
re, polymer oxidation, and particle size were observed for 30 vol% slu
rries of TiO2, Al2O3, and ZrO2 powders in polybutene:fluids. Elasticit
y (in oscillation) and low-shear-rate viscosity (in steady shear) were
observed to increase with increasing temperature for TiO2 and Al2O3 p
articles in oxidized polybutene fluids, This behavior was attributed t
o the creation of interparticle structures, The attainment of this str
ucture on heating was observed to be inhibited by increased oxidation
of the polymer and increased particle size. It was concluded that the
adsorption of oxidized molecules from the polymer liquid, along with t
he high viscosity of the bulk polymer, resulted in suspensions that we
re metastable against coagulation, Increased temperature resulted in l
ower viscosities of the liquid, allowing coagulation on a short time s
cale, The presence of the adsorbed polymer, however, prevented intimat
e contact among the particles so that the coagulated structure was eas
ily destroyed upon subsequent cooling and shearing.