Tailoring the properties of a polymer nanocomposite with a magnetic field

The properties of nanocomposites can be tailored by organizing nanoparticles within the polymer matrix, that is, for potential aerospace, automobile, and infrastructure applications. Multiwalled carbon nanotubes are coated with nickel to produce hybrid Ni‐MWNT nanoparticles. These magnetized nanoparticles are introduced into an epoxy matrix at a relatively low 0.25%–1% volume fraction and oriented along particular directions with an external magnetic field . Changing this alignment makes it possible to tailor the properties of the resulting composite material, that is, its tensile strength, microscopic elastic modulus, and electrical resistivity. The alignment imparts anisotropic properties to the bulk material, but when the nanoparticles are aligned in perpendicular directions in two sequential layers, this coupled orientation produces an overall isotropic composite material. The tensile strength of a nanocomposite containing 0.25 vol% of aligned Ni‐MWNT nanoparticles is ∼9% higher than of pure epoxy. Its AC electrical resistivity along the alignment direction is reduced by ∼20% in comparison with an epoxy composite containing a similar volume fraction of randomly dispersed nanoparticles. These outcomes reveal that, even at a relatively low nanoparticle volume fraction, the alignment of Ni‐MWNTs in epoxy with an external magnetic field induces property anisotropy, which can be tuned through multidirectional alignment. POLYM. COMPOS., 40:779–788, 2019. © 2018 Society of Plastics Engineers