MAGNETORHEOLOGICAL FLUID WITH IMPROVED REDISPERSIBILITY AND METHOD FOR EVALUATING REDISPERSIBILITY OF MAGNETORHEOLOGICAL FLUID

摘要

Disclosed are a magnetorheological fluid and a method for evaluating re-dispersibility of a magnetorheological fluid. According to the present invention, a magnetorheological fluid comprising magnetic particles, a dispersing medium, and an additive, wherein, when all solid components in the magnetorheological fluid are recovered to measure particle size distribution and to obtain a span value (span value) defined below: span value = (D 90 - D 10 ) / D 50 , wherein D 90 , D 10 and D 50 respectively indicate particle sizes corresponding to 90 %, 10 %, and 50 % of the maximum value in a cumulative distribution of particle sizes of solid components, and the span value is 1.3 or more. According to the present invention, a method for evaluating re-dispersibility of a magnetorheological fluid includes providing a transparent container containing a magnetorheological fluid; measuring an amount of light that pass through the transparent container by irradiating near-infrared rays while rotating the transparent container by a centrifuge (primary dispersion stability measurement); re-dispersing the centrifuged solid components into the dispersing medium by applying an external force to the magnetorheological fluid; and measuring an amount of light that pass through the transparent container by irradiating near-infrared rays while re-rotating the transparent container containing a magnetorheological fluid in which the solid components are re-dispersed by the centrifuge (secondary dispersion stability measurement).