| Application of waste rubber in wood composites can help control the viscoelasticity of thecomposites, and is helpful for reasonable utilization of waste rubber resources. This dissertationinvestgated the manufacturing and overlaying process, static and dynamic mechanical propertiesof wood fiber/rubber composites (WRC). Further studies were carried out to modify the suface ofrubber particles to improve wood-rubber bonding strength. The research is hoped to guide theproduction of elastic floorings.First the influence of two factors, i.e., particle size (15-20mesh,20-25mesh, and25-30mesh) and content (0,10%,20%and30%by weight of wood fiber and waste rubber particles) ofwaste rubber, on performance of WRC was analyzed. Glue consumption of3.5%. Hot-pressingconditions were designed as: temperature160oC, time7min, and pressure4MPa. Properties ofWRC including inner bond strength (IB), bending strength (MOR) and modulus(MOE),thickness swelling(TS) were tested and evaluated according to the GB/T17657-1999and LY/T1611-2003standards, respectively. The springback rate (Sr), the static and dynamic mechanicalproperties were tested. It was shown that, with addition of waste rubber particles, WRC haddeceased mechanical properties.The IB of15~20mesh sheet rubber particles from pure fiber1.55MPa to0.86MPa, MOR decreased from35.51MPa to15.21MPa, Sr increased from0.27%to0.93%. Compression test showed that WRC with rubber particles get larger deformation underthe same load, at the maximum load6KN, the amount of thickness defomation of pure fiberboard is1.25mm, while30%waste rubber is2.7mm. With the increase of number ofcompression, the stiffness of pure wood fiber board get increased, while WRC get decreased. Thedynamic thermal mechanical tests show that rubber particles filled in the board increases theinternal friction and heat resistance.And then, study on the overlaying performance and surface roughness of wood-rubbercomposite boards may provide theoretical basis for laminate floorings production. Using ureaformaldehyde resin at10%content, WRC of0.80g/cm3density were made with10%wasterubber particles at15-30mesh, and were then overlaid with resin impregnated paper byhotpressing under2MPa, at180℃and for30s. Surface bond (SB) strength of overlaid WRCwas tested according to the national standard GB/T17657. A new index based on the Arithmeticalmean deviation of the profile Ra, i.e., Ra’, was defined to quantify the surface roughness of WRCbefore and after overlaying. Simultaneously, the micro-surface morphology of WRC were drawnusing the MATLAB software. The SB strength of WRC were0.95~1.05MPa, and combinationof the waste rubber particles showed no evident influences. The Ra’ values of WRC (1.10~1.21 μm) were evidently higher than control (0.73μm). WRC partially lost rubber particles undersanding leaving small pits on board surface, which led to water mark defects on overlaied WRCsurface. However, All boards after overlaying had similar surface roughness. It’s technicallyfeasible to make laminate floorings with WRC, and combination of rubber particles has nosignificant influences on the overlaying performance and surface roughness which can beeffectively quantified by the newly defined index Ra’.At last, Silane coupling agents of bis-(λ-triethoxysilylpropyl)-tetrasulfide (Si69), Bis[γ-(triethoxysilyl) propyl] disulfide (Si75) were tried to modify the rubber particles. In thispaper, the influence of silane coupling agent content (1%,3%,5%by weight of waste rubberparticles), on performance of the composite boards was analyzed. Hot-pressing conditions weredesigned as: temperature150℃, time7min, and pressure2MPa. Physical and mechanicalproperties of WRC were tested and evaluated according to the GB/T17657-1999standards. Itwas shown that, with addition of silane coupling agent, WRC had indeceased MOE whileimproved IB and MOR, the performance of board treated by Si69was well than Si75. Test resultsof rubber particles dynamic contact angle showed that: the dynamic contact angle of the wasterubber treated by silane coupling agent decreased from34.61oto0。... |
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