Dynamic correlation in magnetorheological composite under magnetic field studied by XPCS

The purpose of the research was to check dynamic correlations under magnetic field in the composite type magnetorheological material consisting of polyurethane gel with embedded carbonyl-iron (CI) micrometric spheres. The onion-like sphere structure of CI was destroyed during the composite processing. An X-ray photon correlation spectroscopy (XPCS) study of the composite was performed under magnetic field of 0, 300 and 600 mT. The following conclusions were obtained from the study: (i) The polyurethane matrix is preferred as a source of the observed dynamic effects. (ii) For 300 mT the material dynamics in direction of the outer magnetic field is very clear. (iii) For 600 mT the dependence of the dynamics on magnetic field direction disappears but correlation rate is much higher. This finding may be caused by a disturbance of the polymer mesostructure by larger strain leading to its reinforcement.