Comparison of protein-based adhesive resins for wood composites

The search for new value-added uses for oilseed and animal proteins led us to develop protein-based wood adhesives. Low-fat soy and peanut flours and blood meal were hydrolyzed in an alkaline state, and PF-cross-linked protein resins were formulated by reacting the protein hydrolyzates with phenol-formaldehyde (PF) in solid-tosolid ratios ranging from 70% to 50% hydrolyzates and 30% to 50% PF. Physical properties of medium density fiberboard (MDF) bonded with protein-based phenolic resins were compared to those of boards bonded with ureaformaldehyde (UF) and PF resins, and flakeboard bonded with soy protein-based phenolic resin was compared to PF-bonded board. As MDF binders, adhesive properties of protein-based phenolic resins depended upon protein content of proteinacious materials. MDF board bonded with blood-based phenolic resin was comparable to PF-bonded board and met the requirements for exterior MDF. Boards bonded with soy-protein-based phenolic resin met requirements for interior MDF, while peanut-based phenolic failed to meet some of the requirements. Flakeboard bonded with soy-protein-based phenolic resins was inferior to PF-bonded board but outperformed PF-bonded board in accelerated aging tests. Although they exhibit a slow curing rate, the cost effectiveness and superior dimensional stability of protein-based phenolic resins may make them attractive for some uses.     

山杨木材材性的研究

对北方六省六个地区天然林中的山杨木材解剖, 物理力学性质, 化学成分进行的研究。结果表明：六个种源的山杨木材解剖特征，化学成分无明显差异，物理力学性质存在不同程度的差异。此外，还对六组山杨的胶质纤维，侵填体，髓斑进行了研究。     

Sandwich panel of veneer-overlaid low-density fiberboard

Low-density sandwich panels of veneer-overlaid fiberboards of 12 mm thickness for structural use were manufactured at densities of 0.3–0.5g/cm³ using an isocyanate compound resin adhesive and steam injection pressing method. The effects of board density, veneer thickness, and resin content on the fundamental properties of sandwich panels were examined, with the following results: (1) The dry moduli of rupture and elasticity in the parallel direction of sandwich panels with thicker veneers were superior. The dry moduli of rupture and elasticity in the parallel direction of sandwich panels with 2.0 mm thick veneer at densities of 0.4–0.5 g/cm³ were 40–60 MPa, and 5–8 GPa, which were two and four times as much as those of homogeneous fiberboards, respectively. (2) The higher-density panels exhibited tensile failure at the bottom veneer surface during static dry bending in a parallel direction, whereas lower-density panels experienced horizontal shear failure in the core. (3) The dimensional stability of sandwich panels had good dimensional stability, with negligible springback after accelerated weathering conditions. (4) The thermal insulation properties of sandwich panels were found to be much superior to other commercial structural wood composite panels.Part of this report was presented at the 47th annual meeting of the Japan Wood Research Society, Kouchi, April 1997     

脲醛树脂改性木材的研究

文中介绍了将缓冲式脲甲醛溶液浸注到木材人部后聚合而形成固化脲醛树脂的木材改进性方法。通过实验，研究分析了处理材抵抗干燥收缩、吸湿膨胀和吸水膨胀的效果。结果表明，脲醛树脂改性处理可显著提高木材干燥、吸湿和吸水时的尺寸稳定性，并对木材有明显的增硬作用。     

木片散堆碎料水分迁移系数的研究

本文首次提出利用梯度转换法,实验测定动态传质控制方程中的质扩散系数及传质边界条件中的质交换系数,求算了表面以下蒸发界面深度及其对蒸发速率与相对蒸发深度的关系。实验表明,多孔物料表面下的相对蒸发深度在1%以下时,对质迁移率的影响极为显著。质交换系数也是蒸发界面深度的函数。质扩散系数是含水率的函数。本文采用变系数分段线性化的方法,利用质扩散方程的解析解验算了所求出的质扩散系数、质交换系数及蒸发界面深度的可靠性。理论验算表明,无量纲质迁移势的理论值与实验值之间的相对误差不大于6%,从而说明,利用梯度转换法测定木片料床的质迁移系数的方法是可行的。     

木材软化技术的初步研究

初步研究了两种木材的化学软化技术，通过试验确定了软化剂、软化处理方法。对软化材的化学成分测定和弯曲稳定性的检测结果表明，化学软化剂的配方合理，效果明显，价格便宜，其处理方法简单易行。     

Effects of heat treatment on some properties of MDF (medium-density fiberboard)

This work investigated some mechanical, physical and free formaldehyde emission properties of heat-treated MDF. For this purpose, MDF panels were subjected to varying heat treatment temperatures (155°C, 165°C and 175°C), durations (2.5?h., 3.5?h. and 4.5?h.) and waiting times after hot pressing (30?min., 120?min. and 600?min). Thickness swelling (TS), water absorption (WA), free formaldehyde emission (FFE), bending strength (BS), modulus of elasticity (MOE), tensile strength perpendicular to fibers (TSPF) for treated and untreated samples were tested and evaluated statistically. Consequently, after the heat treatment values of tensile strength, bending strength and modulus of elasticity were almost negatively affected relatively, but the thickness swelling and water absorption and quantities of free formaldehyde were improved positively of MDF samples.     

Formation of the density profile and its effects on the properties of fiberboard

Two main types of fiberboards were produced using lauan (Shorea spp.) fibers with an isocyanate resin as the binder; fiberboard with a flat, homogeneous (homoprofile), and typical U-shaped (conventional) density profile along the board thickness. The processing parameters included manipulation of mat moisture content distribution, press closing speed, and hot pressing method. The results are summarized as follows: (1) A larger variation was observed in the peak density (PD) and core density (CD) of fiberboards at 0.5g/cm³ mean density (MD) level than in those at 0.7 g/cm³. Generally, PD showed a greater variation than CD, irrespective of MD level. (2) Boards produced using two-step hot pressing recorded substantially higher PD with reduced CD. (3) Multiple regression analysis showed that CD and PD could be calculated based on the other profile defining factors, and a rough estimation for peak distance and gradient factor was possible. (4) Based on static bending, conventional fiberboard had a higher modulus of rupture (MOR) than the homo-profile board but a similar modulus of elasticity (MOE). (5) At 0.5 g/cm³ the MOR and dynamic MOE of fiberboard increased by up to 67% and 62%, respectively, when the PD increased from 0.5 to 1.07 g/cm³. Similarly, an increase of PD from 0.7 to 1.1 g/cm³ resulted in corresponding increases of 55% and 34% in the MOR and dynamic MOE of 0.7 g/cm³ boards. (6) The internal bond strength and screw withdrawal resistance were almost entirely dependent on the CD and MD, respectively. (7) Homo-profile fiberboards registered higher thickness swelling and water absorption than conventional fiberboards throughout the dry/wet conditioning cycle.     

Improvement of fiberboard made from acetylated fibers by ozonation I: effect of ozonation on mechanical properties

Acetylated fibers with a 24.8% weight gain by acetylation were ozonated with 0%–2.0% ozone on fibers. Fiberboards were then made from these treated fibers. The internal bond and bending strength of the acetylated fiberboards increased drastically with increasing ozone charge up to 0.5%–1.0%, whereas the thickness swelling of the fiberboards decreased. Ozone selectively cleaves the aromatic rings of hydrophobic lignin and introduces a hydrophilic carboxyl group into lignin. Thus, the wettability and thermoplasticity of acetylated fibers increased, and this structural modification improved the interfiber contact. Internal bond and bending strength increased as a result. In addition, steep density profiles were formed by the ozonation, resulting in high bending strength. The high compaction ratio accelerated the effect of ozonation. The optimum ozone charges for improving mechanical properties were 0.5%–1.0%.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

关于劈刀劈开木材的研究

变更刀具有及木材试件的参数对木材进行劈开试验，从中找出影响木材嬖开性能的诸多因素。设计组合劈刀，探讨用其一次将木材劈开成多块的可能性。     

Effects of low bondability of acetylated fibers on mechanical properties and dimensional stability of fiberboard

Fiberboards were prepared from acetylated fibers with various weight gains: 0, 4.7, 9.4, 18.5, and 24.8 weight percent gain (WPG). The effects of low bondability of acetylated fibers on mechanical properties and dimensional changes were determined. The decreased mechanical properties of acetylated fiberboard are mainly due to low bondability. To improve bending strength, high face density is also needed. The thickness swelling according to JIS and the linear expansion under relative humidity changes decreased with increasing WPG. As for accelerated weathering and the outdoor exposure test, the thickness changes in 4.7–18.5 WPG boards were much higher than those in OWPG board and 24.8 WPG board. The high thickness change in 4.7–18.5 WPG boards is due to low bondability. Although 24.8 WPG board also has low bondability, the thickness change of 24.8 WPG board decreased. The high dimensional stability of acetylated fibers, caused by high WPG, probably outweighs the dimensional change caused by low bondability. On the other hand, during the boiling test the thickness changes in 24.8 WPG board and the 4.7–18.5 WPG boards were higher than those in 0 WPG board. The effect of the boiling test on the boards is more severe than that seen with the accelerated weathering and outdoor exposure test; therefore, the effects of the low bondability probably cancel the effects of the high WPG. It is necessary to increase the bondability of acetylated fibers to improve the dimensional stability and the mechanical properties.     

High-temperature wear of cemented tungsten carbide tools while machining particleboard and fiberboard

Published research on the wear processes of cemented tungsten carbide tools used for machining reconstituted wood products was reviewed, and the current state of knowledge in this area was evaluated. Underlying assumptions and conclusions regarding high-temperature oxidation/corrosion wear during machining were examined in view of known reaction kinetics of cemented tungsten carbide alloys in oxidative and corrosive environments at temperatures that may occur at the cutting edge. This examination indicated that some wear mechanisms other than high-temperature oxidation/corrosion are likely to be rate-controlling when machining reconstituted wood products such as particleboard and fiberboard.     

Effects of physical properties of wood on the water activity of wood meal media for the cultivation of edible mushrooms

The effects of physical properties of wood, including specific gravity, porosity, and water retention, on the water activity (a _w) of wood meal media for the cultivation of edible mushrooms were examined. Five species of wood, selected from an initial set of 11 species, and six species of fungi popularly cultivated in Japan were used. The water activity of each fungal species was measured using liquid media in which a _w had been reduced by adding NaCl, KCl, sucrose, or ethylene glycol. From the water activities of the media and fungi, we estimated the most suitable wood species for the cultivation of each edible mushroom in wood meal media. Suitable wood species for the wood meal cultivation of shiitake, nameko, and maitake, which had relatively high a _w, was limited to hardwoods like arakashi, konara, and irohakaede because of their higher water activities. Edible mushrooms with lower levels of a _w, like hiratake, enokitake, and bunashimeji, could be cultivated in all kinds of wood species used in this experiment, but especially in sugi.Parts of this report were presented at the 49th, 50th, 51st, and 52nd Annual Meetings of the Japan Wood Research Society, in Kyoto (April 2000), Tokyo (April 2001), Gifu (April 2002), and Fukuoka (March 2003), Japan     

THE EFFECT OF WOOD SURFACE ROUGHNESS OF DIFFERENT SPECIES OF TREES ON WOOD COLOR IN WORKING OPERATION

Woodsurfaceroughnessisthemicrogeometrypropertycomposedbyalittlespacingandpeak-tovalley.Generallythesurfaceroughnesswascomposedbytheworkingmethodandotherfactorst123.Woodsurfaceroughnesswasnotonlyanimportantindexwhichmeasuredthesur-facesmoothextentofwoodproductandtheworkingqualitybutalsothewoodsur-fitceroughnessaffectedwoodsurfacefeel--lngandpsychologicalfeeling[3'4,lo,ll:.Th,'quantitativesurftlceproPertyparametersweretheimportantpartwhichmarkedthewoodsurfacevisualpsycho1ogicalmagni-tude,whichha…     

我省引种的任豆木材纤维形态初步研究

试验表明：任豆（Ｚｅｎｉａｉｎｓｉｇｎｉｓｃｈａｎ）的木材纤维形态具有明显的阔叶材特征。其纤维平均长度为１．０１ｍｍ,纤维宽度为２３．１μｍ,长宽比为４３．７;其纤维素含量达５０．１１％,属于高含量的范畴,而木素含量为２２．０１％,则在中等水平。     

传统木材生产与效益木材生产

本探讨了传统木材生产和效益木材生产的区别，并从生产方式和经营模式上具体论述了传统木材生产和效益木材生产。     

论木材检验中造材后的量材改锯问题

本文论述了木材检验中造材后量材改锯中存在的问题。如原木的一断面腐朽为薪材,而另一端为优良断面的木材,如何进行量材改锯等等。并提供了木材改据参考一览表。     

桑木制浆性能的初步研究

研究了桑木的化学组成和纤维形态,并采用硫酸盐法和烧碱法对桑木的制浆性能进行摸索性试验.结果表明:桑木的木素含量为19.31%,综纤维素含量为78.31%,α纤维素含量为47.69%.纤维比量占69.50%,射线比量占16.31%,导管比量占14.19%.纤维平均长度为1 058 μm,长宽比为85.98,壁腔比为0.77.从纤维形态上看,桑木是一种较好的阔叶材造纸原料.两种方法比较,硫酸盐法比烧碱法更适合桑木的制浆.     

Modeling rot in wood by replacement of wood with sand: an experimental study

Rot is known to affect the strength properties of wood. At the same time, the damping properties of the attacked material have also been shown to change. This article presents the results of an experimental study in which rot in wood was modeled by the replacement of wood with sand. The procedure entailed the drilling of holes in the body of a wooden beam, filling the holes with sand, and monitoring the changes induced by the sand-filled holes on the values of the modulus of elasticity (MOE) and of the loss factor. The MOE was calculated from the resonance frequency of the first longitudinal mode of vibration, and the loss factor was obtained indirectly from the impulse response by means of a room acoustical technique. The results show that the MOE value, and hence the strength characteristic of the wood specimen, decreases at the same time as the loss factor increases.