Rheological and cryogenic-transmission electron microscopy probing of the structure of magnetic paints

Abstract

Rheological measurements and cryogenic transmission electron microscopy are used to probe the structure of model magnetic paints which contain ferrimagnetic pigment particles of barium ferrite, a wetting resin, and a solvent. As the resin concentration c increases, the storage modulus goes through a minimum. At low c, a flocculated network is developed in the paint. Milling of the paint at insufficient resin concentration does not improve its dispersion quality, but instead results in the formation of a stronger network. Milling at higher c effectively disrupts the network into small aggregates. The resin concentration required to provide effective milling is lower for paints containing the larger iron oxide particles.