Effect of the alignment of Fe nanoparticles in polyvinyl alcohol film on the morphological, thermomechanical, optical, and magnetic properties

•Polyvinyl alcohol films doped iron nanoparticles were prepared via casting method.•Two polymer films were fabricated, and one was exposed to a magnetic field.•Iron nanoparticles were successfully aligned within a polyvinyl alcohol film.•Alignment of iron in polyvinyl alcohol matrix was identified via optical microscope.•Thermomechanical analysis, and magnetic, and optical properties were investigated. Nanocomposite films of polyvinyl alcohol (PVA) and iron (Fe) magnetic nanoparticles were fabricated by the casting method. Fe nanoparticles were analyzed via a transmission electron microscope (TEM). Two films were fabricated under the same conditions, and one was exposed to a magnetic field (aligned) and another without it (isotropic). The two samples (isotropic & aligned) were studied via a scanning electron microscope (SEM), an optical microscope, and a thermomechanical analysis (TMA). TMA measures the changes in sample dimensions as a function of temperature under a non-oscillatory load with a programmed temperature under constant pressure. The aligned sample exhibits less penetration than pure PVA and isotropic samples. The aligned film exhibits less penetration than isotropic and pure PVA film. Optical properties were carried out using an ultraviolet–visible spectrophotometer. The optical and magnetization properties were investigated for the pure PVA, isotropic, and aligned samples. The bandgap energy decreases after adding Fe to the PVA, and the bandgap for the isotropic sample is lower than that for the aligned one. The magnetizations for the isotropic and aligned samples are 2.75 and 5.05 emu/g, respectively. The exposure of the polymer matrix containing magnetic nanoparticles to the magnetic field helps to change the film structure and makes it promising in medical and optical applications.