Preparation And Characterization Of Persistent Luminescence Of Regenerated Cellulose Fiber

Strontium aluminates(SrAl₂O₄:Eu²⁺,Dy³⁺) has a wide range of applications because of their chemical stability and good luminescent properties. Rare earth luminous fiber is new functional fibers invented by our research group, which has the independent intellectual property right in our country. At present, the long persistence luminescent fiber mainly prepared by melt spinning method, and wet spinning method is less. Because the SrAl₂O₄:Eu²⁺,Dy³⁺ material are sensitive to water. This sensitivity limit the long persistence luminescent fiber preparation methods. This study was aimed to prepare an luminescent regenerated cellulose fiber by solution spinning method. First of all, SrAl₂O₄:Eu²⁺,Dy³⁺ materials were encapsulated with silane coupling agent KH570. Then preparing expected fibers via wet spinning methold, and its performance were studied. Specific content is as follows:In this paper, firstly, silane coupling agent KH570 was applied to modify the long afterglow phosphors. Scanning electron microscopy, X-ray diffraction, FT-IR, TG and Photoluminescence measurements were carried out to characterize the uncoated and coated samples. Fluorescence spectrum shows that the treated samples show similar spectra characteristic with the uncoated sample. This result proves that the introduction of silane coupling agent didn't change the crystal structure of SrAl₂O₄:Eu²⁺,Dy³⁺. Afterglow test indicates that initial intensity of the encapsulated phosphors decrease, however, the decay law hasn't changed. The water resistance test shows that the coated powder can exist in the water stability after 2 hours.In chapter two, photoactive regenerated cellulose fibers were prepared by wet-spinning from NaOH/ thiourea / urea aqueous system and the treated rare earth strontium aluminate powder as an additive. The effects of the concentration of the SAOED phosphors dispersed into cellulose matrices on morphology, crystal structure, mechanical and luminescent properties were investigated. The SEM images indicated that the tendency of the fibers to form the crevices or flaws on the surface of cellulose matrices increased with the increase of modifier concentration into fiber-forming polymer. Nevertheless, with the increasing of the concentration of particles, the tenacity and the elongation at break tends to decrease. The luminescent properties and decay curves indicated that with the increase of powder content, luminous intensity increased, but more than 10%, increasing amplitude are smaller. In addition, the experimental results reveal that the function of silane coupling agent KH570 in the fiber not only enhance the water-resistance, but also increased the fiber mechanical strength.Besides, in order to solve the problem that the color of luminescent fiber's emitting is monotonous, the photochromic compound and luminescent particle were mixed by physical blending. Then, the photochromic fiber was prepared by the same method. The optical properties were characterized. The experimental results showed under the ultraviolet-visible light source excitation, the fiber appears purple, which enrich the color of the luminescent fibers. However, in the dark environment, the fiber exhibited a green color and its emission spectrum blue shift. Luminous performance is not affected by the photochromic compound.