Preparation And Performance Study Of Large Size Wood Fiber Polymer Transparent Materials And Electromagnetic Shielding Materials

Transparent wood has excellent properties such as high transmittance,high haze,thermal insulation,and high strength and toughness,and has broad application potential in fields such as construction engineering,product decoration,and photovoltaic industry.However,this type of "transparent wood" is prepared using raw wood chips as the substrate,which is limited by the delignification process and raw wood chip size.The preparation efficiency is low and the product size is small,which restricts the large-scale preparation,mass production,and industrial application of transparent wood.This article takes large-sized wood fiber polymer transparent materials as the research object,and follows the research ideas of "log substrate fibrosis","polymer matrix porosity",and "material functionalization" to explore efficient preparation methods,influencing factors,and functionalization implementation pathways of large-sized wood fiber polymer transparent materials;Systematically conducting research on material structural characteristics,optics,thermodynamics,acoustics,mechanics,and electromagnetic shielding performance,elucidating the performance characteristics of wood fiber polymer transparent materials,determining their optimized preparation parameters,and revealing material performance optimization and electromagnetic shielding mechanisms.The main work of the paper is summarized as follows.(1)The preparation method and detailed preparation parameters of wood fiber were obtained by using sodium chlorous acid acid solution heat treatment to remove lignin;By analyzing the structure and composition of wood fiber,it shows that this method can effectively remove lignin and hemicellulose,and achieve efficient preparation of wood fiber.In order to improve the efficiency of wood fiber preparation and control fiber parameters,wood powder was used as raw material to prepare wood fibers.40 mesh wood powder fibers and 80 mesh wood powder fibers were prepared.By testing the geometric parameters,structure,and composition of the fibers,it was found that the preparation efficiency of wood powder fibers can be improved by 50.9%,and the fiber length,diameter,and aspect ratio parameters are stable and decrease with the decrease of wood powder size.(2)Wood fiber polymer transparent materials were prepared using PMMA and bisphenol A epoxy resin containing carboxyl groups as polymer matrices,and the optical,thermal,and mechanical properties of the two materials were analyzed.The study found that wood fiber PMMA transparent materials have excellent transparency,thermal insulation,and high strength and toughness properties.When the mass fraction of wood fiber is between 5 wt% and 10 wt%,its comprehensive performance is the best;The transparent material of wood fiber epoxy resin has good comprehensive transparency and insulation properties,but weak mechanical properties.When the mass fraction of wood fiber is 10 wt%,its comprehensive performance is the best.(3)A type of wood fiber reinforced PMMA semi transparent porous material was prepared,and its microstructure,optical,acoustic,thermal,and mechanical properties were systematically studied.The preparation method and process parameters were further optimized.Research has found that this type of material has superior mechanical,thermal,and acoustic properties while maintaining high haze and moderate transparency.Its thermal properties are only about 30% of the thermal conductivity of transparent wood fiber materials;Its sound absorption coefficient can reach 0.6,which is equivalent to that of polyimide foam;Its compressive strength can reach 9MPa,and the energy absorption efficiency can reach more than 90%,which is superior to the currently available metal foam.(4)An efficient method for preparing transparent wood fiber polymer materials using wood powder as the substrate has been established.Wood powder fiber epoxy resin transparent materials and wood powder fiber reinforced PMMA porous materials have been prepared,greatly improving the uniformity of wood fibers in the polymer matrix.Through orthogonal experiments,the effects of wood fiber size,wood fiber mass fraction,and preparation process parameters on material properties were systematically studied.The priority order of factors affecting optical,mechanical,acoustic,and thermal properties was elucidated,and optimized preparation parameters were obtained.(5)A series of wood fiber reinforced epoxy resin electromagnetic shielding transparent materials were prepared using short cut carbon fibers,silicon carbide particles,and nano titanium dioxide particles as electromagnetic shielding fillers.Through orthogonal experiments,the influence of material parameters on the microstructure,absorption performance,and electromagnetic shielding effectiveness of materials was elucidated,as well as the influence mechanism of material components on electromagnetic shielding effectiveness.Corresponding optimized preparation parameters were obtained.Research has found that this type of material has excellent mechanical strength and insulation performance,and can achieve high haze and effective electromagnetic shielding efficiency while maintaining a transmittance of about 50%;When 0.3 wt% short cut carbon fiber and 5.0 wt% wood fiber are added,the comprehensive performance of the corresponding material is the best.(6)A series of wood fiber reinforced PMMA porous electromagnetic shielding materials were prepared with the addition of short cut carbon fibers,silicon carbide particles,and nano titanium dioxide particles.Through orthogonal experiments,the influence of electromagnetic shielding filler components,electromagnetic shielding filler mass fraction,and wood fiber mass fraction on material properties was revealed,and the electromagnetic shielding mechanism of these materials was analyzed based on performance testing results.Research has found that this type of material has excellent electromagnetic shielding,insulation,sound absorption,and mechanical properties,with a maximum electromagnetic shielding efficiency of 64.1 d B in the X-band;When 0.5 wt% chopped carbon fiber and 5.0 wt% wood fiber are added,the overall performance of the material is the best.