Surface characterization of iron particles treated with a polyvinylchloride wetting binder

Commercial iron particles had an oxide layer with an average thickness of 5 nm, consisting of mostly iron and aluminum with some yttrium. The outer surface contains more aluminum oxide than iron and yttrium oxides. After adsorption of MR110 (a polyvinyl chloride binder), the polymer chemisorbed to particle surface mainly through a covalent bond formed between the epoxy groups from the polymer and hydroxyl groups from the surface aluminum oxides. Magnetic dispersions were prepared with cyclo-hexanone solvent. After ball milling the cryo-TEM shows a network structure consisting of aggregates of a few to tens of particles. There was a small fraction of particles that were not in aggregates, which stayed in a diluted dispersion after removing most of the particles by means of a magnetic field. The strong steric repulsion provided by the wetting binder prevented these particles from aggregating even in the presence of a magnetic field.