Nonlinear rheological study of magneto responsive soft gels

作者：An Haining; Picken Stephen J; Mendes Eduardo^*

来源：Polymer, 2012, 53(19): 4164-4170.

DOI：10.1016/j.polymer.2012.07.023

• Nonlinear
• Magnetorheological
• Rheology

Swollen physical magnetorheological (MR) gels were obtained by self-assembly of triblock copolymers containing dispersed magnetic particles. We carry out a detailed investigation of the nonlinear rheological properties of MR gels under large amplitude oscillatory shear flow. A strong Payne effect is observed for strains above 0.05% which is the limit of linear viscoelastic region. The onset strain for the transition from linear to nonlinear viscoelastic behaviour is much smaller than in the absence of a magnetic field. We show that the magnetic Payne effect strongly depends on the magnetic flux density, the particle volume fraction, the sample%26apos;s initial particle distribution and viscoelastic properties of the matrix. %26lt;br%26gt;The rheological response of MR gels is strongly related to the ability for rearrangement of the particles in the presence of the magnetic field. Upon sudden application of a magnetic field, the particle network embedded in a soft matrix becomes more anisotropic than is the case in a hard matrix since the resistance of the matrix to particle rearrangement is smaller. The induced anisotropic particle network parallel to the field provides larger absolute rheological response.

• 出版日期2012-8-31