Fabrication and characterization of metal-core carbon-shell nanoparticles reinforced epoxy nanocomposites

Metal nanoparticles (NPs) were prepared starting from acrylamide complex ofiron (FeAAm) nitrates. Precursors thermolysis at constant temperature in a self-generatedatmosphere lead to formation of metal NPs, whose dimensions depend by the temperatureand the time of synthesis. These NPs were used in different percentages to prepare epoxyresin based nanocomposites.Transmission Electronic Microscopy (TEM) was employed to determine shape anddimensions of the synthetized NPs. Their internal structure was investigated using the X-Raydiffraction, and results have revealed a metal core/polymeric shell structure. These resultswere also confirmed by cross Thermogravimetric analysis (TGA) and vibrating samplemagnetometer (VSM). Optical microscopy, performed on the NPs/epoxy resin system, wasused to determine the obtained dispersion degree. Thermogravimetric analysis was employedto study the effect of NPs on the thermal stability of composites, showing that negligiblevariations are induced by their presence.Thermomechanical characterization, performed using a Dynamic Mechanical Analyzer(DMA), have revealed a slight increase in the room temperature elastic modulus, while moreremarkable variations are induced at high temperature. Glass transition temperature (Tg)does not result significantly affected by the presence of the nanoparticles. A completefracture characterization was carried out to assess the effect of nanoparticles additioncompared to the neat resin system, and the presence of NPs induces a global increase in thefracture energy: this effect is a consequence of the fracture path lengthening. However,higher filler contents are characterized by a lower increase in fracture energy, due to thecoalescence of the voids around the debonded nanoparticles.Magnetic tests, performed using a vibrating sample magnetometer, have revealed theferromagnetic behavior of the iron particles based nanocomposites. In particular, saturationmagnetization and coercivity were found dependent on the diameter of the iron core whichdepends, in turn, by the NPs pyrolysis temperature. Therefore nanocomposites filled withhigh temperature synthetized NPs show a stronger ferromagnetic behavior.