Photocurable magnetic materials with tailored functional properties

Abstract Magnetic materials are among the most commonly required for a wide variety of applications. Further, their fabrication and implementation by means of additive manufacturing technologies are also getting increasing attention. In this context, photocurable magnetic materials based on polyurethane acrylated (PUA) polymer and different magnetic particles including magnetite (Fe3O4), cobalt ferrite oxide (CFO) and neodymium iron boron alloy (NdFeB) have been developed. The influence of filler type and content on the photopolymerization process, sample morphology, Young modulus, electric conductivity and magnetic properties has been investigated. It is observed that increasing particle content diminishes the conversion degree, independently of the filler type. The largest effect on the conversion degree is observed for magnetite (20% degree of conversion for 6.3 wt.% filler content) and the lowest for NdFeB (99% for 6.5 wt.% sample). Fe3O4 and CFO particles form small agglomerates within the sample, which increase with filler content, whereas NdFeB shows a good degree of dispersion. Regarding the mechanical properties, a remarkable decrease on the Young modulus of the films prepared with iron oxide-based fillers is observed, while the inclusion of NdFeB shows an increase in the Young modulus. Finally, magnetic properties are characterized by an increase in the saturation magnetization and remanence with increased filler content, while the coercivity remained constant for all filler types. A maximum magnetization of 3.70, 3.50 and 49.64 emu/g is obtained for Fe3O4, CFO and NdFeB based composites. This demonstrates the possibility of easily developing materials with tailored magnetic response by means of additive manufacturing technologies.