Polymeric materials to self-regulate the level of polar activators in electrorheological fluids
AssigneeThe Lubrizol Corporation
InventorsBarton J. Schober, Joseph W. Pialet, Robert A. Pollack, Denise R. Clark
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Abstract
Electrorheological systems of improved temperature range are obtained by including within the system a solid polymer insoluble in a low molecular weight activating material and in the hydrophobic medium of the fluid. The polymer contains hydrophilic functionality, and in the polymer a portion of the low molecular weight polar activating material is sorbed in an amount which reversibly increases with increasing temperature.
Claims16
An electrorheological fluid system comprising:
- (a) a hydrophobic liquid medium having a boiling point of at least about 150.degree. C.;
- (b) a dispersed particulate phase comprising water-insoluble organic particles which are capable of exhibiting substantial electrorheological activity only in the presence of an activating material, in an amount of about 5 to about 50 percent by weight of the total of components (a), (b), and (c);
- (c) an alcohol activating material of a molecular weight of about 230 or less in an amount of about 1 to about 15 percent by weight of the total of components (a), (b), and (c);
- and
- (d) an effective amount of a solid crosslinked polymer to reduce the increase in conductivity of said electrorheological fluid system at elevated temperatures, said polymer being distinct from the particles of (b), insoluble in said hydrophobic medium, containing hydrophilic polyalkylene oxide functionality and urethane linkages, and capable of sorbing said low molecular weight polar activating material, the amount of said sorption increasing with increasing temperature and being at least in part reversible, said polymer being present in an amount of about 1 to about 100 percent by weight of the total of components (a), (b), and (c) and wherein said solid crosslinked polymer is in the form of particles which are separate from the particles of (b).
A method of reducing the effect of temperature on the electrical properties of an electrorheological fluid which comprises
- (a) a hydrophobic liquid medium having a boiling point of at least about 150.degree. C.;
- (b) a dispersed particulate phase comprising water-insoluble organic particles which are capable of exhibiting substantial electrorhological activity only in the presence of an activating material, in an amount of about 5 to about 50 percent by weight of the total of components (a), (b), and (c);
- (c) an alcohol activating ineterial of a molecular weight of about 230 or less in an amount of about 1 to about 15 percent by weight of the total of compoennts (a), (b), and (c);
- said process comprising including within said electrorheological fluid an effective amount of a solid crosslinked polymer to reduce the increase in conductivity of said electrorhcological fluid at elevated temperatures, said polymer being distinct from the particles of (b), insoluble in said hydrophobic medium, containing hydrophilic polyalkylene oxide functionality and urethane linkages, and capable of sorbing said low molecular weight polar activating material, the amount of said soprtion increasing with increasing temperature and being at least in part reversible, said polymer being present in an amount of about 1 to about 100 percent by weight of the total of components (a), (b),and (c), and wherein said solid crosslinked polymer is in the form of particles which are separate from the particles of (b).
Dependencies are inferred from the claim text.