| Poplar is an important raw material supporting the development of China’s wood industry,but its low strength, hardness, texture soft, easy warpage natural defects, the added value ofexisting poplar wood processing products is relatively low, so the modification treatment, toovercome its own shortcomings, improve the poplar utilization value, has the important theorysignificance and practical value to expand its range of use.In this thesis, poplar wood plate was used as the research object. In order to improve thestrength, hardness and dimensional stability, the reasonable experiment was designed. With thehelp of microscopy, contact angle tester, FTIR spectrometer and other modern analysis methods,production is suitable for rapid soaking water-based resin. The test studied swelling and crosslinking, impregnation and carbonization process in order to study the mechanical properties anddimensional stability. The change of pore structure, sample chemical group microscopiccharacteristics and influence on the subsequent painting process were analyzed, drawing aprocess to effectively improve the wood strength and dimensional stability. Conclusions of thestudy are as follows:(1) Research the preparation process of modified agent, the suitable impregnated with highsolid content, low viscosity, high permeability, good storage stability of three kinds of modifiedagent (2D resin, MF resin and poplar powder-phenol liquefaction product-formaldehyderesin)were researched. Using polyethylene glycol inflation and three kinds of agent vacuumpressure impregnation modification, two steps treatment on the effect of immersion, thereasonable impregnating processing craft was identified: Firstly, the temperature was55℃,polyethylene glycol water solution treated specimen of24~36hours, under low temperature,drying to the moisture content about10%. Secondly, three kinds of modifiers filled test pieceunder the vacuum pressure impregnation treatment. The specimen was evacuated to-0.098to-0.09MPa, keeping1hour, vacuum feed, and continue to maintain30minutes. Finally, usingnitrogen the specimen was pressurized to1.2to1.5MPa, keeping2hours.(2) Polyethylene glycol impregnated inflation and three kinds of agent modified and crosslinked treatment, which can effectively increase the strength and improve the dimensionalstability of poplar wood. After2D resin impregnation, the dimensional stability, hardness,strength are best; after MF resin treatment, the MEE and ASE could obviously increase; afterliquefaction resin treatment, the hardness, MOR, MOE and compressive strength perpendicularto grain were improved.(3) Considering the result of modification and economy benefit, selecting2D resin as thefinal modifier analyze the suitable time, optimizing impregnated inflation and impregnatedcross linking process. The result time is2hours. The WPG was46.1%. In this condition, the physical and mechanical properties can be improved in some extent. After the modification, theradial and tangential hardness were respectively1.34times and1.67times comparing to emptylumber; the MOR, MOE and wear resistance were improved; the FTIR spectroscopy andmicroscopic image analysis, after vacuum pressure impregnation of2D resin cross linkingmodification, the modification agent infiltrated into wood material inside, and completelytogether with wood.(4)Analyzing three kinds of modifier, after the impregnation and carbonizationmodification, the physical and mechanical properties of wood was studied. By2D resinmodified, the MEE and ASE were69.22%and130.71%. The hardness was3.46KN and3.51KN, far beyond the empty lumber. The MOR and MOE were85.45MPa and8.92GPa; thecompressive strength perpendicular and parallel to grain were respectively12.81MPa and73.24MPa, more than empty lumber. In general, three kinds of modifier, the2D resin isrelatively good about the specimen impregnation carbonization composite modification.(5) Surface wettability results: Impregnation and carbonization modification are better toreduce the wood surface wettability effect.2D resin treatment lumber reduced significantly.The surface coating adhesion is better compared with the material; MF resin treatment lumbercan also effectively reduce the surface wettability, MF resin and liquefaction resin inflation andcross linking treatment lumber, the wettability decreased un-conspicuously.2D resin inflationcross linking, impregnation and carbonization modification, can reduce the absorption of poplarlumber, which helps to improve the dimensional stability. |
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