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Measurement of the dynamic modulus of elasticity of wood panels

中国高等学校学术文摘·林学 2006年第4期1卷 425-430页

作者： LIU Zhenbo LIU Yixing YU Haipeng YUAN Junqi Key Laboratory of Bio-based Material Science and Technology Ministry of EducationNortheast Forestry UniversityHarbin 150040China

This study investigated the dynamic modulus of elasticity (DMOE) of wood panels of Fraxinus mandshurica, Pinus koraiensis, and Juglans mandshurica using the natural frequency measurement system of fast Fourier transform (FFT). The results were compared with the static modulus of elasticity (E S) tested by a mechanical test machine. The results show a significant correlation between E S, transverse vibration DMOE (E F), and longitudinal vibration DMOE (E L). For all of these species, the correlation between E S, E F and E L is more significant than the individual species, which indicated that the FFT method is universal. The correlations between E S and sample’s density (ρ) are significant, but the correlation coefficient of E S and ρ is lower than those between E F, E L and E S. The E S of wood is more accurately tested by the analysis based on FFT measurement than by the estimation based on density.

关键词： lumber non-destructive test dynamic modulus of elasticity

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Adhesive application method in MDI-UF particleboard manufacture

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中国高等学校学术文摘·林学 2006年第2期1卷 225-229页

作者： Wang Weihong Zhang Xianquan Lu Renshu Key Laboratory of Bio-based Material Science and Technology of Ministry of Education Northeast Forestry UniversityHarbin 150040China

Chinese wood-based composite manufacturers are plagued with serious formaldehyde emission (F-emission) problems. In this study, we investigated the use of an emulsifiable diphenylmethane-4, 4′-diisocyanate (MDI) — urea formaldehyde (UF) mixture adhesive in particleboard manufacture, in order to decrease F-emission to below 9 mg per 100 g board. We paid close attention to the effect of NH4Cl on MDI-UF curing and the method of adhesive application by differential scanning calorimetric (DSC) analysis and compared mechanical properties. Both results showed that the acidic agent NH4Cl did hinder EMDI-UF curing and it also affected the adhesive application method. We are of the opinion that when EMDI and UF are mixed first, without adding NH4Cl and then sprayed onto particles, mechanical properties will be improved and F-emissions will meet E1 grade requirements.

关键词： UF-MDI adhesive mixture formaldehyde emission particleboard curing agent separate application mixing application

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Dynamic-mechanical analysis and SEM morphology of wood flour/polypropylene composites

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Journal of Forestry Research 2006年第4期17卷 315-318页

作者： GUO Chui-gen SONG Yong-ming WANG Qing-wen SHEN Chang-sheng MOE Key Laboratory of Bio-based Material Science and Technology Northeast Forestry University Harbin 150040 P. R. China

A study was conducted to investigate the effects of compatibilizers, including Maleic anhydride grafted polypropylene （MA-PP） and maleic anhydride grafted ethylene-propylene-diene copolymer （MA-EPDM）, on wood-flour/polypropylene （WF/PP） composites. WF/PP composites were prepared by direct extrusion profiles using a twin-screw/single-screw extruder system. DMA analysis showed that the loss factor of composites decreased and the storage modulus improved in the presence of MA-PP, which indicated much better interfacial adhesion between the PP matrix and wood flour filler than in the absence of compatibilizer. Morphological feature based on SEM observation showed that MA-PP and MA-EPDM improved the dispersion of the wood particles in the plastic matrix. MA-EPDM is a soft segment, although it improved the interfacial adhesion, storage modulus decreases with adding of MA-EPDM. As compatibilizer of wood-flour/polypropylene composites, both DMA analysis and SEM feature proved that MA-PP was superior to MA-EPDM.

关键词： Wood flour Polypropylene Composites Dynamic-mechanical analysis

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Manufacture technology and Nondestructive Test of Wood / Waste Styrofoam Composite

Manufacture Technology and Nondestructive Test of Wood / Was...

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2006中日稻米品质测控及美味技术学术研讨会

作者： HU Ying-cheng Key Laboratory of Bio-based Material Science and Technology of Ministry of Education College of Material Science and EngineeringNortheast Forestry University Harbin 150040 China

Manufacture technology of wood / waste styrofoam composite was investigated. The possibility that the dynamic Young's modulus of wood / waste styrofoam composite can be measured by nondestructive testing method was also discussed. The following conclusions have been drawn. Wood / waste styrofoam composite can be manufactured under the hot press condition of 155℃, 1 MPa for 7 minutes. The dynamic Young's moduli measured by longitudinal transmission method were bigger than those measured by longitudinal vibration method and flexural vibration test. The dynamic Young's moduli measured by in-plane flexural vibration test were less than those measured by out-plane flexural vibration test.

关键词： wood / waste styrofoam composite manufacture technology nondestructive test dynamic young's modulus

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Nondestructive Testing of Adhesive-bonded Wood

Nondestructive Testing of Adhesive-bonded Wood

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第三届世界粘接及相关现象大会暨北京粘接学会第十五届学术年会

作者： HU Ying-cheng College of Material Science and Engineering Northeast Forestry University Key Laboratory of Bio-based Material Science and Technology of Ministry of Education Northeast Forestry University

Nondestructive testing means to determine characteristic of a material without altering intrinsic properties and shape during the *** this paper,the dynamical properties of adhesive-bonded wood were measured by nondestructive test(vibration method).From experimental results,dynamic Young's modulus of adhesive-bonded wood can be measured by longitudinal transmission method and flexural vibration *** Young's modulus measured by longitudinal transmission method while two acceleration pickups attached to the ends of two wood panels is less than that two acceleration pickups attached to the ends of one wood panel or adhesive *** Young's moduli of the adhesivebonded wood measured by longitudinal transmission method while two acceleration pickups attached to the ends of two wood panels and out-plane flexural vibration method are relatively close.

关键词： adhesive-bonded wood nondestructive testing dynamic Young's modulus

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Preparation of electromagnetic shielding wood-metal composite by electroless nickel plating

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Journal of Forestry Research 2006年第1期17卷 53-56页

作者： WANG Li-juan LI Jian LIU Yi-xing Key Laboratory of Bio-based Material Science and Technology （Northeast Forestry University） Ministry of Education Harbin 150040 China

Electrical and electromagnetic shielding wood metal composite was prepared by using electroless nickel plating. The effects of solution amount, plating time and plating temperature on surface resistivity and electromagnetic shielding effectiveness were investigated. And P content, microstructure and surface feature of layers obtained at different temperatures were analyzed by energy dispersion spectrometer （EDS）, X-ray diffraction （XRI）） and scanning electron microscopy （SEM）. The results showed that layers with higher electro-conductivity and electromagnetic shielding effectiveness were obtained under the optimum conditions that plating solution was 500 mL, plating time was 30 min and plating temperature was 62℃. The results showed by EDS analysis; that P content increased gradually in a small extent with plating temperature increased. It was showed by XRD and SEM analysis that layers plated at different temperatures were all microcrystalline structure and uniform and successive, which had noticeable metal luster. Those indicated that plating temperature had little influence on microstructure and surface feature under pH value invariable.

关键词： Wood veneer Electroless plating Composite Surface resistivity Electromagnetic shielding

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Review on Volatile Organic Compounds Emission from Wood Composites

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Chinese Forestry science and technology 2006年第1期5卷 26-32页

作者： LIU Yu YU Yaoming SHEN Jun LIU Ming The Key Laboratory＇ of Bio-based Material Science and Technology Northeast Forestry University Harbin 150040 P.R. China Beiyinhe Foresto Station Wuchang 150200 P.R. China

The problem of indoor air quality (IAQ) is mainly caused by the volatile organic compounds(VOC) emission from the wood-based composites. As a material for decoration, furniture manufacturing orbuilding, wood-based composite is one of the sources of VOC emissions. Most of them are formaldehyde,terpene, ketone and benzene. The paper reviews on VOC emission of wood-based composites at home andabroad, including the source of the VOC, its impacts on IAQ, its emission during processing and using, theusual sampling and analyse methods of VOC in different conditions. Meanwhile, main problems existed inthe past researches are summarized and some suggestions are put forward.

关键词： wood-based material volatile organic compounds indoor air quality

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The stability of reverse microemulsion polymerization system based on DADMAC/AM/AA

Shiyou Huagong Gaodeng Xuexiao Xuebao/Journal of Petrochemic...

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Shiyou Huagong Gaodeng Xuexiao Xuebao/Journal of Petrochemical Universities 2006年第4期19卷 56-59页

作者： Su, Wen-Qiang Yang, Kai-Ji Shen, Jing Key Laboratory of Bio -Based Material Science and Technology Northeast Forestry University Harbin 150040 China

Taking cyclohexane as the oil phase, DADMAC, AM and AA as the monomers, based on the emulsifying system comprised of nonionic surfactants Span80 and Tween60, effects of monomer concentration, monomer fraction, hydrophile-lipophile balance(HLB) value, the dosage of emulsifier as well as electrolytes on the stability of inverse microemulsion were studied by method of conductometry and eyeballing. The experimental results show that stable inverse microemulsion system can be formed with the mass fraction monomer in the range of 50% to 65%, the stability of inverse microemulsion continuously increases with the increase of acrylamide based on the fixed mass fraction of the monomers. It is also found that the system with HLB value in the range of 5.36 to 8.54 is stable and is most sable with the HLB value of 7.48, the inverse microemulsion system is more stable when used more emulsifier, additionally, introduction of electrolytes into the system can make particles further fine and enhance stabilization performance.

关键词： Conductivity Electrolyte Inverse microemulsion Stability

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Effect of heating methods on drying quality of small-diameter birch lumbers

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Journal of Harbin Institute of technology(New Series) 2005年第5期12卷 536-539页

作者：郭明辉赵西平闫丽 Key Laboratory of Bio-based Material Science and Technology Northeast Forestry University Harbin 150040 China

Following a normal low temperature drying schedule, the small-diameter Birch lumbers （ 1 000mm× 45mm ×30mm） were dried with consecution-heats or intermittent-heating, visual drying defects （bow, crook, twist, check along grain and end check） were measured, and then statistical analyses were performed. It was found that the drying quality of small-diameter Birch lumbers could be improved with intermittent-heating, but the intermittent time should be prolonged. Prolonging intermittent time helped to weaken or even avoid wood distortion and drying checks. It wash＇ t helpful in avoiding crook. The drying quality of small-diameter Birch lumbers with all kinds of drying methods reached the second class of the Chinese National Standard. The drying quality reached the first class of the Chinese National Standard with the intermittent-heating in the area of visual wood defects.

关键词： small-diameter timber birch lumber consecution-heats intermittent-heating drying quality

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Modification of larch wood by intensive microwave irradiation

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Journal of Forestry Research 2005年第3期16卷 237-240页

作者： LIU Hong-Hai WANG Qing-Wen YANG Lin JIANG Tao CAI Ying-Chun MOE Key Laboratory of Bio-based Material Science and technology Northeast Forest University Harbin 150040

The larch wood was treated by microwave irradiation under different radiant intensity and treating duration. The microwave-treated wood specimens together with the un-treated for comparison were impregnated by water in pressure vessel and then tested for permeability, mechanical properties and microstructure change by SEM to study the modification performance of microwave treatment on larch wood. The results showed that under suitable conditions of microwave treatment the permeability of larch wood was improved without noticeable decreasing of the modulus of rupture （MOR） and the modulus of elasticity （MOE）. The radial parenchyma and some pit membrane were ruptured, and tiny cracks were formed in the cell walls. The formation of tiny cracks in the cell walls serves as man-made channels of gas and liquid and this contribute to improve the permeability of the wood.

关键词： Larch wood Modification Microwave irradiation Permeability

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