Magnetic and Viscoelastic Properties of Iron Oxide–Poly(ethylene oxide) Nanocomposites

Current research aims to characterize the magnetic and viscoelastic properties of iron oxide (Fe₃O₄) nanoparticle (NP) filled poly(ethylene oxide) (PEO). Iron oxide NPs with varying surface chemistries are used to prepare nanocomposites with concentrations of less than 1% iron oxide by weight. Magnetic heating, magnetic property characterization and nanoindenation experiments were carried out on hot pressed cylindrical samples. Samples were subjected to stress relaxation experiments where loading rates were varied while hold times and unloading rates were held constant. Previously, Huang-Lu showed that loading curves can be used to extract viscoelastic properties of materials. Using this model, loading curves were fit and the influence of loading rate on loading response as a function of NP surface chemistry and NP loading was determined. Additionally, the dependence of heat generation mechanisms and interfacial heat transfer on the matrix molecular weight and nanoparticle concentration was explored. Understanding the rotational dynamics of magnetic NPs is important in the application areas of these nanocomposites. The relative importance of Brownian and Neel relaxation processes can be determined by altering the polymer matrix viscosity.