Properties of green SrAl _2O_4 phosphor in LDPE and PMMA polymers

摘要

Different contents of SrAl _2O _4:Eu, Dy, one of the long afterglow phosphorescent materials with high brightness, were melt-mixed with low-density polyethylene (LDPE) and Polymethyl methacrylate (PMMA) polymers, respectively. The morphology and composition of the samples were observed by means of a scanning electron microscope (SEM) coupled with an energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and transmission electron microscope (TEM). Sharp and broad X-ray diffraction (XRD) peaks were observed for the LDPE and the PMMA composites respectively, reflecting configuration characteristics similar to those of the respective pure polymers. TEM micrographs show a transition from nanosized particles to cluster formation with increase in phosphor concentration. The green long-lasting phosphorescence of the composites was observed in the dark after removal of the excitation light. Photoluminescence (PL) was observed in the composites of both polymers for phosphor volume concentrations above 1.0% for PMMA and above 0.5% for LDPE. For each of these samples, a broad PL peak at about 505 nm wavelength was observed after excitation at 350 nm with a xenon lamp. For the LDPE composites, the DSC results show that the presence of the phosphor in the polymer has no major influence on either the melting temperature or enthalpy values of the polymer.