Investigation of Magnetic Force for Barium and Strontium Ferrites

A new method is presented for calculation of the maximum magnetic force of magnetic ceramics, based on their crystalline structure. The results of this model for the magnetic forces of barium and strontium ferrites are compared with experimental values. In this comparison, the experimental values are less than the values determined by the theoretical model for various magnet cross-sectional areas. This difference is due to the presence of crystal imperfections and incomplete alignment of the magnetic domains. In addition, the magnetic forces of barium and strontium ferrites are a sensitive function of their heat treatments.     

Photodegradation of low-density polyethylene with prooxidant and photocatalyst

Low-density polyethylene (LDPE) composite films with trisilver phosphate (Ag₃PO₄) and cadmium selenide (CdSe) particles as photocatalysts and manganese stearate as prooxidant were prepared. The film samples were irradiated under UV and visible light and their photodegradation were evaluated using Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. The carbonyl index of the photocatalyst containing samples was very higher than the pure irradiated LDPE and even prooxidant containing film. The morphologies of the irradiated composite films were completely changed and had many cavities and cracks. The thermal stability of the composites was very lower than the pure polyethylene. However the crystallinity of the LDPE films with photocatalysts was enhanced contrarily the LDPE film with manganese stearate. Generally the results showed that the combination of the prooxidant with photocatalyst have synergistic effect on the photodegradation of the LDPE and can be used to accelerate the degradation of the polyethylene films.