Synthesis, non-isothermal crystallization and magnetic properties of Co_(0.75)Zn_(0.25)Fe_2O_4/poly(ethylene-co-vinyl alcohol) nanocomposite

摘要

The synthesis of Co_(0.75)Zn_(0.25)Fe_2O_4/poly(vinyl alcohol-co-ethylene) (ferrite/PEVA) nanocomposite was carried out through two steps: impregnation of the ferrite particules by PEVA and then mixing the ferrite/PEVA impregnated with PEVA solution. A non-isothermal study of the crystallization kinetic of ferrite/PEVA nanocomposite was carried out by differential scanning ealorimetry (DSC), scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. It was observed that the Ozawa equation describes perfectly the primary process of non-isothermal crystallization of ferrite/PEVA system. There is a strong dependence of the ferrite/PEVA composition on the crystallization parameters. The crystallization activation energy (E_a) calculated from the Xu and Uhlmann model increased by increasing the ferrite content in ferrite/PEVA nanocomposites between 3 and 7 wt% and decreased dramatically beyond these values. The results revealed that the ferrite nanoparticles were uniformly distributed throughout the PEVA matrix. The percentage of magnetization of the composite decreases as the concentration of the ferrite increases.