RHEOLOGICAL PROPERTIES OF NANOCOMPOSITES FeCo@C-N BASED ON SUSPENSIONS IN PAO LIQUID PHASE

This paper will focus on rheological induced effect of FeCo/C-N nanocomposite particles in polyalphaolefin (PAO) as liquid medium for potential application in magnetorheological system. FeCo/C-N nanoparticles synthesized by frontal polymerization followed by thermolysis were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM); the nanoparticles were finally dispersed at different content percentage in a PAO liquid medium to investigate the inherent rheological variation of the final suspension due to the presence of the filler loading. According to the XRD data, the diffraction peaks for FeCo are in good agreement with the standard diffraction pattern for the face-centered-cubic Fe-Co alloy. TEM images showed the formation of nanoparticles with an average size of 10 nm, and elemental analysis reveals the presence of a carbon-doped layer. Analysis of the suspension prepared showed that the loss modulus (G?) exceeds the storage one (G?) in the full range of the considered stress amplitude, supporting the conclusion that the presence of nanocomposite particles strongly enhance the viscoelastic behavior of the base medium. According to the studies carried out in this work, the liquid medium exhibits a Newtonian flow over the entire spectrum of shear stresses; the maximum area of effective operation of the suspensions is up to 1 Hz. The relevant change in viscoelastic behavior of the employed liquid medium due to the presence of synthesized particle paves the way to the concrete application of this metallopolymer-based particle to design magnetorheological components or systems characterized by an inherent damping performance.