AC magnetorheology of polymer magnetic composites

Abstract

Determination of the rheological behavior of polymer magnetic composites is required for real-time industrial processing and incorporating advance material feedback loops. However, the rheological behavior in the presence of an alternating magnetic field (AMF) has many technical challenges with respect to unwanted induction of nearby electronics and testing probes. For the first time, a custom-made magneto-rheometer is designed to quantitate viscoelastic adhesives susceptible to alternating magnetic fields (AMFs). The dynamic viscosity, complex modulus, and temperature profiles are correlated with the cumulative AMF exposure, thermal conductivity, particle loading and nature of non-ferrous support materials. Magnetoadhesive composites reached the gelation point in less than 1 min after AMF exposure. Epoxy resins exceeded 11 MPa shear modulus at strains of <10% under an AMF of 140 Oe. The crosslinking kinetics are strongly correlated with Curie nanoparticle loading, substrate thermal conductivity, and initiation temperature. For the first time, optimum process parameters for magnetic field processing of polymer magnetic composites are determined using a high-throughput approach.