Study On The Preparation Process Of The Strengthening-dyeing Compound Modification Of Plantation Poplar Wood

As one of the three fastest growing woods,plantation poplar wood had very rich resources,but its inherent defects,such as small density,low strength,poor dimensional stability,monotonous color,unobvious texture pattern and poor decoration,greatly limited its application,so it was necessary to improve its physical and mechanical strength by modification and then to promote its comprehensive utilization and raise the added value of its products.In this study,the effects of different dyes,solution pH values and photostabilizers on the performance of MUF-dye compound modifiers were discussed.The strengthening-dyeing compound modification technology of plantation poplar wood were optimized through orthogonal tests;the physical and mechanical properties,the color and color fastness of the treated wood were evaluated;and the modifing and dyeing mechanism of the compound modifier were discussed by SEM and FTIR analysis.The main results were as following:?1?The miscibility,storage time and the treated wood properties of the compound dyeing modifiers of different dyes and different solution pH values were investigated by single factor analyzing,and the dye of acid red G and the solution pH value of 10 were selected out.?2?The effect of different photostabilizer on the weight percent gain,the color and color fastness of the treated wood were studied,and the compound photostabilizer of UV-531 and nano-TiO₂ was selected out.?3?Taking MUF resin concentration,dye concentration,photostabilizer concentration and resin curing temperature as four factors,L₉?3⁴?orthogonal tests were conducted to optimize the preparation technology of the strengthening-dyeing compound modifier;based on the properties of the treated woods such as density,weight percent gain,color and color fastness,the results of the orthogonal tests were analyzed by range analysis and variance analysis.The comprehensive evaluation results showed that the optimum preparation technology was MUF of 30% concentration,Acid Red G of 1.5% concentration,UV-531 and nano-TiO2 of 0.5%concentration respectively,and the curing temperature of 100?.?4?Compared with the untreated wood,the density,modulus of elasticity?MOE?,and modulus of rupture?MOR?of the compound modified wood increased by 46.15%,29.67% and54.36% respectively,and its ASE was above 70%;Compared with the wood dyed in water solution,the compound dyed wood had more uniform,bright and beautiful color;its color fastness to water was good,while its color fastness to light still needed to be further improved.?5?SEM anlysis showed that the compound dyeing modifier had good permeability;it could be effectively penetrated into the cell lumen and intercellular space of plantation poplar wood;a large amount of resin was immersed in wood vessel elements and the surface of wood cell wall was fully covered with resin.?6?FTIR analysis showed that the spectra of the compound dyed woods were similar to those of MUF strengthened woods,which indicated that the modifing mechanism of the compound dyeing modifier was the same to that of MUF resin;the improved physical and mechanical properties of poplar wood were mainly due to the filling effect of MUF resin and its cross-linking reaction with wood cell wall compositions.