Ultraviolet Aging Resistant Properties Of Rare Earth Complexes Modified Fluorescent Wood-Based Materials

Wood is easily influenced by ultraviolet,moisture,biological and other aspects,it will make the irreversible physical and chemical reactions on wood surface.Among the aspects,ultraviolet irradiates on wood surface will make the surface discoloration,even the crack,the process greatly affected the wood properties and its services life.With the researches of wood surface clearly,the studies of functional wooden materials' properties have gradually increased.In order to expand the application of wood,increase the usage and stability in outside condition,ultraviolet aging resistant property of wood surface became a hot spot.In recent year,fluorescent wooden material shows up in new research topics.The rare earth complexes modified fluorescent wood,besides of fluorescent property,reduces the influence of water to wood surface.At the same time,the antibacterial properties of the rare earth complexes reduce the influence of microorganisms on the surface and improve the stability of wood surface,but there are few studies on its resistant of ultraviolet aging.For increasing wooden materials'usage and researching the property of fluorescent wood,it is necessary to study the ultraviolet aging property of wood surface and to have research on functional modification of it,so as to enhance its stability and prolong the service life of wood.In this paper,using silane coupling agent and o-benzoyl chloride to prepare modified ligands,1,10-phenanthroline as auxiliary ligands to coordinate with rare earth ions in different conditions to get silane-modified Eu3+ complexes,silane-modified Eu3+ternary complexes and silane-modified Tb3+ complexes.The modified rare earth complexes were reacted with poplar wood/poplar wood flour to prepare modified wood,and then have an ultraviolet aging test for 480 h.Through the detections of surface microstructure and surface color,the influence of preparation conditions on the chemical elements,microstructure of wood surface before and after ultraviolet aging and surface color changes during aging were analyzed.In order to study the fluorescent intensity stability of modified wooden material,poplar wood flour was chosen as raw material,the influence of preparation conditions on the fluorescence stability of modified wood flour was analyzed by testing the fluorescent intensity of modified wood flour during the aging process.The results are as follows:Comparing the three kinds of silane-modified rare earth complex modified wood materials'performance in surfaces' microstructures and color change with natural wood during ultraviolet irradiation,the three kinds of modified wood all have smaller change values of surface color than natural wood and find the best conditions for preparing the modified wood in every index of color.For silane-modified Eu3+complex modified wood,the results shows that a high reaction temperature of 75? and ratio between Eu3+and ligand of 1:3 are beneficial in obtaining surface color stability modified wood;a reaction time of 8 h and reaction concentration of 0.08 mol/L exert great influence on surface color stability when the reaction temperature of synthesizing the sample is 45?.For silane-modified Eu3+ ternary complex modified wood,the change value of total color change is closely related to the preparation conditions of the Eu3+ ternary complex.When the ratio of Eu3+ ion and silicane-modified ligands is constant,the change value of total color change of the modified wood increasing with the number of 1,10-phenanthroline increases;the change value of total color change decreasing at beginning then increasing,when of Eu3+ ternary complex reaction temperature and reaction concentration increases.For silane-modified Tb3+ complex modified wood,the change value of total color change is decreasing at beginning then increasing when reaction time of Tb3+ complex is increasing;the change value of total color change decreasing with the reaction temperature increasing.In the ultraviolet aging experiment of modified wood flour,the fluorescence performance of three kinds of modified wood flours,it proves that the surface of modified wood-based material has good ultraviolet aging resistant property,but there are some differences in three kinds of materials.For silane-modified Eu3+complex modified wood flour,there has a large fluorescence intensity fluctuation but the fluorescent intensity increased during the ultraviolet irradiation.The silane-modified Eu3+ternary complex modified wood flour has most stable fluorescent intensity in three materials,the result shows that a reaction temperature of 65? and ratio Eu3+:ligand:1,10-phenanthroline of 1:1:1 are beneficial in obtaining fluorescent intensity stability modified wood flour when the reaction concentration is 0.04 mol/L.For silane-modified Tb3+complex modified wood flour,the fluorescence performance of modified wood flour is relatively stable and the fluorescent intensity decreased slightly.