Two-body and three-body abrasive wear properties of katsura wood

Two-body and three-body abrasive wear tests of katsura wood were carried out using abrasive paper and moving abrasive grains, respectively. The two-body and three-body abrasive wear properties were investigated and compared. The wear rate of two-body abrasive wear was two orders of magnitude larger than that of three-body abrasive wear. Moreover, two-body abrasive wear of katsura wood increased with higher applied surface pressure, whereas three-body abrasive wear did not always depend on the applied surface pressure. Based on these results and observation of the wear surface profiles, it is suggested that two-body abrasive wear is more affected by yield stress and surface microstructure, and three-body abrasive wear is more affected by the cutting action of moving abrasive grains. Furthermore, during wear tests with different abrasive grain sizes, critical grain size effects of two-body abrasive wear were observed at low applied surface pressures but not at high applied surface pressures. The critical grain size effects of three-body abrasive wear were observed at both low and high applied surface pressures.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Abrasive wear properties of compressed sugi wood

We examined the abrasive wear properties and the effect of abrasive grain size on the rate of wear when sugi wood (Cryptomeria japonica D.Don), compressed to various densities, was rubbed with abrasive paper. The results showed that the wear resistance of compressed wood increased linearly with the increased compression ratio; and under the condition of a low compression ratio it tended to be higher in comparison with the strength of compressed wood. The critical grain size effect, which can be witnessed during the abrasive wear of metals and plastics, was seen when low pressure was applied to the abrasive material. At higher pressures, the wear rate of the compressed wood increased with grain size, but the critical grain size effect was not observed. The pressure required to create the critical grain size effect was found to be higher than that needed for other types of uncompressed wood with the same yield properties.Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000     

欧美杨107杨正常木与应拉木制浆造纸性能比较

选取直立和倾斜欧美杨107杨为研究材料,根据正交试验确定正常木和应拉木最佳制浆条件,比较正常木和应拉木的制浆造纸性能,通过提高打浆转数对应拉木纸张性能的提高进行探讨。结果表明:正常木的最佳制浆条件为用碱量15%、最高温度164℃、最高温度保温时间75min;而应拉木最佳制浆条件为用碱量13%、最高温度160℃、最高温度保温时间40min。用碱量对正常木和应拉木制浆得率和卡伯值影响的通径系数在不同水平上显著。通过对正常木和应拉木制浆造纸性能比较发现,应拉木比正常木制浆得率高、卡伯值低、纸张力学性能均低,且抗张指数和耐破指数差距较大(约2倍),而撕裂指数差距较小。正常木和应拉木之间卡伯值、制浆得率、抗张指数、耐破指数均在0.001水平上差异显著,撕裂指数在0.05水平上差异显著。结合纸张断口形貌分析认为,胶质层的存在使得应拉木纤维成纸时不容易扁平坍陷,极大地阻碍了成纸时纤维之间的结合,因此降低了纸张力学性能;但是,由于其胶质层纤维素含量很高,因此其制浆性能优于正常木。随着打浆转数的提高,应拉木纸张力学性能增强,且接近正常木纸张水平,但过高会降低纸张力学性能。     

P180号砂布磨削规律的研究

文章以 P180号砂布为研究对象，测试并分析100，200，300，400和500 r 时3种品牌砂布的磨削规律，为实木地板100 r 表面耐磨测试提供指导。结果表明，上海现代品牌的砂布500 r 校准结果在95~125 mg 范围内，砂布质量满足 GB/T 15036—2009实木地板要求；3种品牌砂布的磨耗规律基本一致，100 r 时砂布的磨削能力最强，磨损量在25~37 mg 之间；随着耐磨转数的增加，砂布的磨削能力逐渐减弱。     

Agricultural residues in panel production – Impact of silica particle content and morphology on tool wear

Abstract

Considering ongoing global deforestation and the increased demand for raw materials in all wood-processing sectors it is necessary to seek and employ alternative resources. Agricultural residues are potential sources of alternative lignocellulose-based raw materials. Research on substitute materials for wood panel production mainly focused on physical and mechanical properties of boards while much remains to be learned about machining. Therefore, studies were carried out to analyse the relationship between ash and silica content and their impact on tool wear. Ash and silica contents of agricultural residues were determined following ISO 3340. Particle morphology and elemental composition of selected materials were analysed using scanning electron microscopy and energy-dispersive X-ray analysis. Tool wear tests were carried out using particleboards made from wheat straw, canola straw and spruce. Analyses of various plant materials displayed no correlation between ash and silica content. Bio-mineralised silica structures in wheat and canola were different compared to coarse silica found in wood-based particleboard. Tool wear caused by these agricultural residues was just moderately increased compared to wood, despite the fact that their silica contents were many times higher. Furthermore, the impact of abrasive substances on wear behaviour was influenced by the density of the panels.     

杉木无性系木材尺寸稳定性研究

以29个12年生杉木无性系为试材,采用随机区组法取样,3株小区,3次重复,对其进行生长锥无损取样分析。结果表明:杉木无性系间木材径向全干干缩率差异显著或极显著;性状遗传力为0.20,变异系数为23.4%,遗传变异系数为14.9%,无性系间木材径向全干干缩率差值变动幅度为0%~2.3%。     

Comparison of Quality of Pulping and Paper-Making between Normal Wood and Tension Wood of Poplar Clone 107(Populus×euramericana‘Neva’) Tree

Both of straight and inclining poplar clone 107 tree were selected for studying materials in this paper.The optimal pulping conditions was established by orthogonal experimental design both for normal wood and tension wood,and the quality of pulping and paper-making between normal wood and tension wood was compared with each other. Finally,potential application for improving paper quality of tension wood through increasing beating revolutions was discussed.The result showed that the optimal cooking condition for normal wood was alkali concentration 15%,the highest temperature 164℃,time at highest temperature 75 min,and for tension wood it was alkali concentration 13%,the highest temperature 160℃,time at highest temperature 40 min.Path coefficient of effect of alkali concentration both on pulp yield and kappa value was significant at different levels.By comparison between average result of normal wood and tension wood in quality of pulping and paper-making,it was found that tension wood had higher pulping yield and lower kappa value than normal wood. Furthermore,for all mechanical properties of paper, normal wood hold higher value than tension wood, and even near two times than tension wood,such as burst index and tensile index.However,difference of tear index was quite narrow.Result of one way ANOVA showed that difference of burst index and tear index between normal wood and tension wood was significant at the 0.001 level,of tear index was significant at the 0.05 level.Based on observation of cross surface of paper,it was assumed that contribution of gelatinous layer to rigidity of single fiber had hampered collapse and compression of fiber during paper formation,which is essential for exerting combination between fibers in paper.So, mechanical properties of tension wood paper were decreased accordingly.However,owing to high cellulose content of gelatinous layer,tension wood was easier to pulping than normal wood.Mechanical properties of tension wood paper could be improved by increasing beating revolutions,     

Effects of five additive materials on mechanical and dimensional properties of wood cement-bonded boards

There is a growing desire to improve the properties and use of nonwood plant materials as supplements to wood materials for wood cement-bonded boards (WCBs). This study was conducted to determine the comparative properties of WCBs containing various amounts of discontinuous inorganic fiber materials, such as alkali-resistant glass fiber, normal glass fiber, mineral wool, and nonwood plant materials such as retted flax straw and wheat straw particles. Tested cement-bonded boards were made at wood/additive compositions of 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (weight percentages). Seventy-eight laboratory-scale WCBs were produced. Various board properties, such as the modulus of rupture (MOR), internal bonding strength (IB), water absorption (WA), thickness swelling (TS), and linear expansion (LE), were studied. The test results showed that three types of discontinuous inorganic fiber used as reinforcing materials in composites significantly enhanced and modified the performance of WCBs. The mechanical properties and dimensional stability of cement-bonded board were significantly improved with increasing amounts of the additives. MOR and IB were increased; and WA, TS, and LE of boards were reduced by combination with the inorganic fiber materials. The results also indicated that combination with retted flax straw particles only slightly increased the MOR of boards, and wheat straw particles led to marked decreases in all the mechanical properties and the dimensional stability of WCBs.Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000     

木材及木基材料吸湿尺寸稳定性检测方法研究

为实现木材及木基材料吸湿尺寸稳定性横向比较,规范其检测方法,依据现有相关检测标准,借鉴日本工业木材吸湿尺寸稳定性检测方法,结合木质材料特性以及我国的具体情况,提出一种木材及木基材料吸湿尺寸稳定性的检测方法,即以温度20℃、相对湿度65%条件下的材料尺寸为基准,测定在温度40℃、相对湿度为75%和90%的两种吸湿环境条件下的材料尺寸变化。通过该方法对柚木、印茄木、朴木3种不同尺寸的木材和对多层材料、高密度纤维板、普通刨花板3种木基材料的吸湿尺寸稳定性进行测定,以评价该方法的适用性和可行性。结果表明:木材与木基材料试样不超过12 d即可达到吸湿平衡,不同材料尺寸变化率、湿胀系数的大小关系也与实际情况一致。因此木材与木基材料试样均适于用该方法。     

不同织构形式硬质合金表面与木材径切面的摩擦性能

合理的微坑型微织构已被证明具有改善木材和硬质合金表面间的摩擦特性。采用微凹坑型织构、微凹槽织构和微网格型织构3种织构形式,在相同织构面积占有率条件下,通过摩擦特性试验与理论分析相结合,研究不同织构形式对木材表面摩擦系数的影响。研究表明:在相同织构面积占有率条件下,不同织构的类型和表面形貌对硬质合金试样与木材表面摩擦的摩擦系数有不同的影响,受摩擦长度、凹槽微织构宽度、微织构角度等织构参数的影响。当微织构与木材发生摩擦时,摩擦区域织构面积越大说明两者间实际接触面积越小,且面积越大,捕捉磨屑和硬质点的能力越强;而主制动力越小,其产生的摩擦系数越小。在相同压力和织构面积占有率条件下,不同类型的织构试件与木材表面产生的摩擦系数均小于非织构(平面)型表面产生的摩擦系数。其中:微坑型织构产生的表面摩擦系数最小,为0.116;凹槽型织构产生的表面摩擦系数最大,为0.182;网格型织构随着织构角度的减小,其产生摩擦系数越小。     

Effect of annual rings on abrasive wear property of wood

In this study we investigated the abrasive wear property of Douglas fir (Pseudostuga menziesii Franco) on abrasive paper using test specimens with various dimensions and annual ring widths. The effect of the annual rings on the abrasive wear property of Douglas fir was clarified from the relation with the compression strength of the wood specimens. The dispersion of the wear coefficient, which was calculated as the wear volume divided by the friction distance and the load applied to the friction surface, varied when there were fewer than approximately three annual rings in the specimen, as did the compression strength. As clarified from these results, it was found that the effect of the annual rings on the abrasive wear and compression properties of Douglas fir is closely related to the earlywood/ latewood ratio.Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000     

Effect of fatigue and annual rings’ orientation on mechanical properties of wood under cross-grain uniaxial compression

The mechanics of fresh wood with and without a fatigue pre-treatment that mimics a mechanical pulping process was experimentally studied. The mechanical properties of Norway spruce samples under compression are considered with the macroscopic stress–strain data and from local strain properties via digital image correlation technique. The results highlight the effects of the orientation of the wood annual rings compared to the loading direction and of the pre-fatigue. The wood presents a low yield point when the annual rings are tilted compared to the load axis, but the Young’s modulus and yield stress are higher when the annual rings are either parallel or perpendicular to the load direction. In the last case, buckling of softest layers occurs. The fatigue treatment makes the wood less stiff as deduced from the decreases of Young’s modulus and yield stress, whatever the orientation of annual rings. Secondly, it creates a thin and localized softened layer.     

Effect of heat treatment temperature and time on sound absorption coefficient of <Emphasis Type="Italic">Larix kaempferi</Emphasis> wood

Heat treatment improves the dimensional stability and hydrophobicity of wood, and heat-treated wood is currently attracting attention as a new interior material. However, there are few evaluations where the acoustic properties of heat-treated wood are reported when such wood is used as an interior material. In this study, Larix kaempferi wood, typically used as a building material, was heat-treated at 200, 220, and 240 °C for 9, 12, 15, and 18 h. The sound absorption coefficients of the treated wood samples were measured at 250, 500, 1000, 2000, and 4000 Hz in a reverberation room. The sound absorption coefficient increased with the treatment temperature and the treatment time. The results of this study showed that the high-frequency band range sound absorption coefficient of wood can be increased dramatically by heat treatment.     

Identification of moisture-induced stresses in cross-laminated wood panels from beech wood (Fagus sylvatica L.)

The crosswise bonding of the layers in laminated solid wood panels results in internal stresses when the humidity varies. The layers hinder one another as a result of the anisotropy of wood. The purpose of this study was to determine the internal stress state in free and constrained swelling. The expansion properties in the three panel directions were measured. Furthermore, the swelling of samples was constrained while the resulting forces were recorded. Hygroscopic warping experiments were carried out inducing a climate gradient within the panels. Afterwards the stresses were calculated from released deformations and non-destructive measurements of the Young’s modulus. The materials used were untreated and heat-treated beech wood, the latter modified in two levels. In addition to homogenously structured panels, treated top layers were combined with an untreated middle layer. Swelling, swelling pressure, warping and internal stresses considerably decreased from untreated to treated wood. If layers from treated and untreated material were combined, stresses and deformations increased as compared to the variants produced only from treated wood. It was concluded that the lower equilibrium moisture content of heat-treated beech wood improves its dimensional stability, which results in smaller deformation differences between the layers. Hence, the stresses were less distinctive.     

杨树浸渍改性材物理及力学性能研究

利用聚乙烯醇缩甲醛复合改性剂对杨树木材进行浸渍改性处理,对比研究了杨树素材与改性材的物理性能及主要力学性能的变化,并利用扫描电子显微镜(SEM)分析了改性剂在改性材中的分布情况。结果表明:改性材的气干密度和抗缩系数(PASE)随改性剂浓度的上升而增加,改性材的气干密度最高为0.41 g/cm3,比素材的提高了13.9%,抗缩系数(PASE)最大提高到47.8%。改性材吸水率随改性剂浓度的上升而下降,与素材相比最大下降了19.2%。当改性剂的浓度为25%时,改性材的弹性模量和静曲强度达最大,分别为27.4%和13%。SEM分析显示改性剂填充于部分木射线以及交错纤维间的空隙中。     

Effect of knife wear on finger-joint strength of silver fir (Abies alba) wood

Abstract

This study was carried out to determine the effect of knife wear, as measured in hours of use, on the finger-joint strength of silver fir wood (Abies alba), bonded with polyurethane (PU) and polyvinyl acetate (PVAc) adhesives. Wood samples were collected after 1, 32 and 64 h of knife wear. Results showed that as knife wear increased, bending strength or modulus of rupture (MOR) of the finger-jointed samples was reduced by 11.1% (PVAc) to 21.2% (PU) after 32 h of knife wear, and by 19.6% (PVAc) to 27.6% (PU) after 64 h of knife wear, whereas modulus of elasticity (MOE) of the finger-jointed samples was reduced by 10.5% (PVAc) to 12.5% (PU) after 32 h of knife wear, and by 11.7% (PVAc) to 10.0% (PU) after 64 h of knife wear. Tension strength of the finger-jointed samples was reduced by 2.1% (PVAc) to 1.5% (PU) after 32 h of knife wear, and by 5.4% (PVAc) to 16.0% (PU) after 64 h of knife wear.     

AMINO RESIN FLAME RETARDANT FOR WOOD

INTRoDUCTIoNThechemicalscommonlyusedforflameretardantstowoodincludeammoniumphosphate,phosphoricacid,boricacid,borax,hydratedalumna,am-moniasulfate,zincchlorideandmagne--siumcNoridetl'2j.Thesechemicalsareimpregnatedasaqueoussolutionsintothewoodwheretheyaredepositedwithintheporesandcapillariesofthewoodwhenthesolutionevaporates.Butthesechemicalsarenotsuitableforexteriorandunder-groundconstructionwheretheflameretardantsareleachedeasily[3:.Nowanimportantdevelopmentorientationofstudyingonflamere…     

Heat treatment of wet wood fiber: A study of the effect of reaction conditions on the formation of furfurals

Abstract

Furan monomers are produced when wood is heated at high temperatures. To understand the process conditions for production of furfural (FF) and hydroxymethylfurfural (HMF) from wood, samples of milled aspen wood were subjected to autohydrolyzis by microwave heating in a sealed Teflon reactor. The experiments were designed to simulate temperature and pressure variables of a fiberboard press and their effect on production of furans from the hemicelluloses that have the potential for promoting self-bonding of the wood fibers. The effect of a Lewis acid catalyst, AlCl₃·6H₂O on the formation of FF and HMF was also studied. The hydrolysates were analyzed for the liberated wood sugars and dehydration products, FF and HMF. The FF and HMF yields under autohydrolyzis conditions increased with increase in severity factor, CS. Under catalyzed hydrolyzis conditions, the FF yield decreased, while the HMF yield increased with increase in severity factor. Under catalyzed hydrolyzis conditions the FF yield decreased presumably due to degradation reactions including resin formation. The increase in HMF yield with increasing severity factor was most likely due to hydrolyzis of glucan from cellulose. These results suggest that FF and resin yields could be enhanced with the addition of a Lewis acid catalyst to the wood particles, but that process variables need to be controlled in order to avoid or minimize degradation of the wood cellulose.     

Wear and blunting of the tool corner in cutting a wood-based material

Summary A study was made of relationships between wear (loss of metal) and blunting (reduced performance) of the corner of a steel cutting tool turning a work-piece of hard fibreboard. Rake angle, clearance angle and surface preparation (grinding, polishing) were varied and measurements made were the three cutting force components and various wear parameters. It was confirmed that retraction of the edge from its initial position is not a satisfactory index of blunting and that the shape parameter corresponding to compression of the cut surface (negative clearance) was most influential. Also, for the particular tool and work-piece materials used and in the practical range of bluntness, the ratio of negative clearance to the width of the back wear land, as measured parallel to the cutting plane, was roughly constant. It is evident that development of a hard, very thin layer on the back face would minimize negative clearance and extend sharpening life. In the practical range for cutting wood and wood-based materials, clearance angle had a relatively small effect on the rate at which negative clearance and cutting forces increased, and rake angle had negligible effects. It is concluded that these angles should not be increased without taking into account factors other than blunting. Polishing considerably decreased blunting rate, especially of the tool corner, which is especially important in sawing. The expense of polishing may be justified in some exacting operations.     

A THEORY OF DETERMINING MASS TRANSFERPARAMETERS FOR WOOD PARTICLE MATERIALS

INTRoD[JCTIONTllcrcsearcI1OI1tl1ctI1c111opl1}'sIcalprop-crtiesofl1catandl11asstransfcrproccsscsi11``oodparticlcl11atcrlalsisratllcrlll11ltcdcur-rcntI}O11l}afct`papcrssofarasconccn1slllnybclbund(Slla11g.19(j()).Ho\tc\cr'tl1cullll,attol1a11dtI1cproductionof\"oodcl1ipa11dx`oodslla\lngctc.Asra\`matcrlals(Sl1ang*I()9l)forpulpandpapcr'paniclcboards'\\'oodfucl(Martalcna.l988)ort\'oodpaFticlc111atc-rialhascdcom6ositcproductsarcincrcasil1goxcrtllcx"orldTllccfficicnttechnolog1caIllandlil1gofth…