Study On Dyeing, Enhancement And Dimensional Stability Of Fast-growing Poplar

With people's increasing demand for living, wooden decorated structural material will be one of wood composite research directions in several decades. However, in a long period our country not only will face the embarrassment of short of timber provided, but also will be confronted with problem of constructional match due to serious lack of big-diameter-class and precious, natural timber. If high grade decorated structural GLULAM with high strength, good dimensional stability and precious wooden color could be made from fast-growing Poplar, the cost could be less and the value of Poplar could be higher. In accordance with the actual situation of research and application of poplar board,　the key study of this paper is studying on Poplar dyeing, enhancement and dimensional stability. In dye experiment, inner wood dyeing process was preliminarily discussed based on experiment using orthogonal design (L33) under vacuum and heat The studying results showed that at a given formulation of dyeing solution, concentration of dyeing solution and vacuum, temperature of dyeing solution was the most effective factor to dyeing and color fastness. Level dyeing agent was one of important factors to dye up which made each part of timber color up possibly even by relaxed and adjusted color fastness speed of dyestuff. At the same time, there was slight negative influence to colour fastness. After analysis, The optimal dyeing technology conditions was temperature was 80℃, pH was 6.5, concentration of level dyeing agent was 1.5% and concentration of fixing agent solution was 3‰. In enhancement and dimensional stability experiment, Poplar was modified with heat pressure treatment, high temperature steam treatment and low molecule resin impregnation treatment. The results showed that each modified material had inimitable feature. For Example, Compression wood can attain high value of MOR and MOE, when compression ratio exceeded 30%, the value of MOE can reach over 10000MPa, but its dimensional stability was unqualified. Although Material's dimensional stability can be improved apparently after high temperature stream treated, which the value of ASE can go up to 31.8% after was treated one hour at a given temperature was 125℃, steam pressure was 0.1MPa, the value of strength descended 20% than untreated samples. Impregnation wood had better dimensional stability and higher strength than untreated samples, but yet didn't meet up to Japanese Agricultural standard for wood products-Structural Laminated Timber. Dyeing, hot pressing and resin impregnation were combined together after test method improvement. The results showed that the value of MOE of test samples reached over 11000MPa and MOR reached more than 110MPa, perfectly meet up to Japanese Agricultural standard. Dimensional stability of test specimen was better than untreated samples. It was basic to attain the request of decorated structural Glued Laminated Timber.