In-situ observation of the movement of particles in thermoplastic polyurethane magnetorheological elastomers using computed x-ray microtomography

Abstract Magnetorheological elastomers (MREs) belong to a class of smart materials that incorporate the elasticity of a soft polymer matrix with the magnetic responsiveness of embedded micro-particles. The combination of these distinct properties allows for significant changes in mechanical properties under external magnetic fields, known as the magnetorheological (MR) effect. In this study, computed x-ray microtomography was employed to investigate the microstructure and particle movement within a thermoplastic polyurethane based MRE under varying conditions. The sample was characterized at two different temperatures, both with and without the application of a magnetic field. Particle tracking was performed to analyze the movement of individual particles, and the global particle arrangement was characterized using the direction-dependent pair correlation function. The in-situ observations revealed distinct particle movements and microstructural changes influenced by magnetic fields and temperature. This study offers valuable insights into the translation behavior of particles in addition to the comparison of changes in their global particle structure with the MR effect.