Preparation and characterization of persistent luminescence of regenerated cellulose fiber

Persistent luminescence of regenerated cellulose was successfully prepared via wet-spinning from NaOH/thiourea/urea aqueous solvent system. The morphologies, phase structures, mechanical and luminescent properties of the prepared fibers were characterized by SEM, fluorescence microscope, X-ray diffraction (XRD), tensile tester, photoluminescence spectroscopy and brightness meter, respectively. Moreover, the effect of concentration of luminescence phosphors was investigated. The SEM images indicated that the SrAl₂O₄:Eu²⁺, Dy³⁺ particles (10 wt%, average size of 6 μm) were uniformly incorporated in the cellulose fibers, which provide the fibers with smooth surface. The XRD results show that the prepared composite fibers had a typical crystalline structure of cellulose II and SrAl₂O₄:Eu²⁺, Dy³⁺. Interestingly, the presence of 8 % phosphors in fibers’ matrix had no negative influence on tenacity. Nevertheless, with the increasing of the concentration of particles from 8 to 12 %,the tenacity and the elongation at break tends to decrease. The luminescent properties indicated that luminous fiber exhibited a yellow–green emission band with a maximum of 520 nm originating from SrAl₂O₄:Eu²⁺, Dy³⁺. Decay curves of the composite fiber have a similar tendency with SrAl₂O₄:Eu²⁺, Dy³⁺ pure powder, but slightly longer decay tended than the SrAl₂O₄:Eu²⁺, Dy³⁺ particles.