夹具与槽口距离对胶合板强度测定结果的影响

通过试验,研究了胶合板胶合强度检测试验中夹具与试件槽口的距离对胶合板胶合强度的影响.结果表明,当夹具与槽口的距离在0～40 mm内时,距离值与胶合强度检测值呈一定的线性相关.距离在0～15 mm区间,胶合强度随距离增大呈现增加的趋势,之后则逐步减小.相距15 mm时板的胶合强度最大(1.71 MPa),距离为40 mm时胶合强度最小(1.11 MPa).方差分析的结果表明,夹具与试件槽口的距离对胶合强度检测结果有显著的影响.     

小径柚木异型胶合工艺对集成材胶合性能的影响

以胶合压力、施胶量(单面)、加压时间为影响因素,通过正交试验优化小径柚木胶合工艺,在此基础上研究胶合工艺参数、组合纹理与异型单元件斜边角度对集成材胶合性能的影响。结果表明:优化胶合工艺参数为胶合压力0.7 MPa,施胶量(单面)220 g/m^2,加压时间40 min;胶合压力对胶合剪切强度有显著影响,施胶量(单面)和加压时间对胶合性能影响不显著,随着胶合压力增大,胶合剪切强度随之减小。异型单元件斜边角度和不同纹理组合都对胶合剪切强度有显著影响,对木破率无显著影响。随着梯形组坯单元件斜边角度的增加,胶合剪切强度增加。在弦弦、径弦、径径纹理组合中,弦弦组合纹理胶合剪切强度最大。     

现代胶合竹的超声波检测与轴压强度的试验研究与分析

胶合竹材料作为一种竹材深加工产品,具有强度高、性能稳定、适宜工业化生产加工等特点。为深入研究胶合竹材料的力学性能,对7组共70个基材叠合方向、试件长度不同的胶合竹清材小试件进行了超声波波速检测和轴心抗压强度试验。试验结果显示,胶合竹材料具有较高强度,破坏以试件基材破坏而非胶层剥离为主。胶合基材的叠层方向对超声波速和刚度、轴压强度影响较大,超声波速与强度、弹性模量具有一定相关性,因此可以基于超声波波速指标对胶合竹试件的强度和弹性模量进行无损检测。通过各试件的抗压强度曲线可以发现,顺纹抗压试件的强度明显高于2类横纹抗压试件,后者在试验后期仍可产生获得强度提升,3类试件都具有较大的塑性变形能力,3类试件不同的力学特性可以使其应用于不同的场景。     

胶合木层板配置与其强度性能

胶合木层板配置与其强度性能郝金城（黑龙江省林产工业研究所）王世鑫李金杰（哈尔滨国营松江胶合板厂）１试验目的胶合木与天然木材的区别在于胶合木是由层板胶合而成的材料，它可以人为地配置不同层板，然后胶合成胶合木。层板配置不同，其胶合木的强度性能有较大的差异...     

酶处理对麦秸表面胶合性能的影响

研究麦秸单元经过纤维素酶和半纤维素酶处理后的表面润湿性能、化学基团和胶合强度的变化.结果表明:在试验区间内,随着纤维素酶和半纤维素酶用量的增加,麦秸的表面胶合强度逐渐上升,UF树脂对麦秸表面接触角逐渐减小;酶处理时间的延长,有利于麦秸表面胶合强度的提高.     

胶合板用淀粉基水性异氰酸酯胶黏剂的研究

对玉米淀粉进行化学改性,通过酸解、氧化、接枝等方法制得酸解氧化淀粉,以其作为AP胶的主要成分,应用于杨木单板的胶接,通过正交试验分析各因素对胶合板湿胶合强度的影响.试验结果表明,反应温度、反应时间、玉米淀粉乳浓度对胶合强度的影响较显著,以最佳配方胶黏剂压制的胶合板,其胶合强度达到GB/T 9846-2004 II类的要求.     

改性大豆蛋白胶黏剂制造杨木胶合板热压工艺

利用单因素试验方法,研究了热压温度、热压时间、热压压力和施胶量对使用改性大豆蛋白胶黏剂制造的杨木胶合板胶合强度的影响规律.结果表明:在100～ 220℃热压温度范围内,随着热压温度的增加,胶合强度显著增大;在35～60 s/mm热压时间范围内,胶合强度随热压时间的增加呈上升趋势,当时间从60 s/mm升至85 s/mm,胶合强度几乎保持一致;热压压力在1.25 MPa时,胶合强度达到最大值;施胶量在130 ～430g/m2热压时间范围内,胶合强度随施胶量的增加呈上升趋势.由此得出最优工艺参数为:热压温度180℃,热压压力1.25 MPa,热压时间60 s/mm,施胶量为310g/m2.     

集成材常用胶粘剂的性能试验

集成材是采用胶粘剂将短材或低质材胶合而制造的材料,其质量在很大程度上取决于胶粘剂的性能。集成材的基本要求是具有足够的胶合强度和良好的耐久性。而胶粘剂种类不同,集成材的胶合强度和耐久性差异较大。因此,了解各种胶粘剂的性能,正确选择和使用胶粘剂,对保证集成材的质量是非常重要的。为了了解集成材的各种胶粘剂的胶合性能,正确选择集成材的胶粘剂,我们选用了几种胶粘剂,并进行了集成材胶合性能的试验。本试验是以落叶松和水曲柳为代表树种,进行6种胶粘剂的性能试验,其中选择一种日本生产的间苯二酚胶粘剂与国内生产胶粘剂进行对比试验。一、试验方法1.试验材料     

节子对落叶松胶合木胶合性能的影响

采用水性高分子-异氰酸酯(API)胶黏剂对含有木节的兴安落叶松(Larix gmelinii)层板按照工程胶合木的胶合工艺进行常温加压胶合,探讨木节及其大小对兴安落叶松工程胶合木胶合性能的影响。通过对试件进行胶缝剪切强度试验和浸渍剥离与煮沸剥离试验,发现节子对胶缝常态剪切强度、木破率、浸渍剥离率和煮沸剥离率均有显著的影响,随着木节直径的增大其胶缝剪切强度和木破率可下降40%和67%以上,浸渍二次总剥离率和煮沸二次总剥离率可增大至16%和37%以上。研究表明:两胶合面中仅一面有小木节(占板宽1/7~1/6),只能用于室内结构用集成材,不能用于室外结构用集成材;只有尺寸小于木板宽度1/10的木节与无节面胶合才能满足室外用工程胶合木的要求。     

纤维素/半纤维素酶处理对杨木表面胶合性能的影响研究

研究了速生杨木单元经过纤维素酶和半纤维素酶处理后的表面润湿性能、化学基团和胶合强度的变化。结果表明:随着纤维素酶和半纤维素酶用量的增加,杨木的表面自由能和胶合强度逐渐上升。在试验区间内,酶处理时间越长,杨木的胶合性能改善效果越明显。     

胶合板胶合强度测试中不确定度评定

依据GB/T 9846-2004《胶合板》标准,对胶合板胶合强度测试过程进行研究,分析了胶合强度测量过程主要不确定度的来源并对其进行评定。介绍了胶合强度测量不确定度的评定方法和步骤,对各不确定度分量进行量化,得到了胶合强度的合成不确定度和扩展不确定度。     

Development of new natural polymer-based wood adhesives I: dry bond strength and water resistance of konjac glucomannan,chitosan, and their composites

 Bonding properties of konjac glucomannan (KGM), chitosan, and their composites were investigated. After preparing three-ply plywood glued with these materials, the dry bond strength and the bond strength after water immersion treatment were measured. The bond strength of urea-formaldehyde resin adhesive, casein, and soybean glues was also studied for comparison. KGM developed relatively good dry bond strength in extremely small solid amounts, irrespective of alkaline treatment. However, the water resistance was extremely low for all of the conditions. Chitosan also developed good dry bond strength in small solid amounts and was better than conventional adhesives. Chitosan also exhibited excellent water resistance compared to casein and soybean glues. When KGM and chitosan were combined, the adhesiveness under the dry condition was enhanced, and the bonding properties were superior to those of casein and soybean glues. Therefore, it is expected that chitosan and chitosan–KGM composite can be used as environmentally friendly wood adhesives. Received: March 18, 2002 / Accepted: July 5, 2002 RID="*" ID="*" Part of this paper was presented at the 51th Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001     

Strength of profile-adhesive joints

The current article presents an attempt to describe the strength of profile-adhesive joints. Its main objective was to develop mathematical models describing phenomena occurring in bent mortise joints prevalent in constructions of skeleton furniture, but also to determine factors influencing the strength of profile-adhesive joints. The presented cases of gluing of a mortise joint reveal that mutual interactions of compressed wood surfaces influence significantly the strength of the developed node. In extreme cases, when a glue bond fails to form on surfaces of elements, the strength of the joint will depend only on the compression strength of wood. That is why, despite the impairment of the adhesive bond, the construction will still be able to carry considerable outside loads. However, the best situation is when well fitted elements of the joint, compressing one another, reduce stresses in the glue bond and increase its strength above the value of outside loads exceeding greatly the shear strength of the glue. Received 1 November 1999     

三聚氰胺改性低毒脲醛树脂耐水性研究

不同摩尔比的两类低毒脲醛树脂(JQ21未改性,JQ22与5%三聚氰胺共聚),分别与不同质量比的三聚氰胺树脂混合,并在不同的固化体系中固化,用于胶合板的压制.对胶合板的胶合性能及甲醛释放量进行了研究.实验结果表明:固化体系不同,胶接强度也不相同;随着摩尔比的增加,胶接强度提高,甲醛释放量亦相应提高;同时采用共聚和共混两种方法进行改性的脲醛树脂,其胶接强度和甲醛释放量均优于单一的采用共混改性的脲醛树脂;并且混合胶液中三聚氰胺的比例越低,胶接性能越筹,甲醛释放量变化逐渐趋于平稳.     

单板层积材的加速老化性能研究

本文对高频胶合的马尾松LVL和杨木LVL的老化性能进行了讨论,并比较了乳液酚醛树脂胶和酸固化酚醛树脂胶在BDB28和A1080加速老化后的胶合剪切强度的损失率。得出的结论如下:1)乳液酚醛树脂肢胶合的马尾松LVL,胶合剪切强度随老化时间的延长逐渐趋于稳定,最后稳定在老化前强度的70％左右;2)乳液酚醛树脂胶的老化性能比酸固化酚醛树脂胶好;3)对于乳液酚醛树脂胶马尾松LVL和酸固化酚醛树脂胶杨木LVL,可以用BDB28处理方法代替A1080加速老化方法快速测定其胶合剪切强度的损失率。     

提高低甲醛释放胶合板胶合强度的研究

为提高低甲醛释放胶合板胶合强度,研究了4类改性剂对胶合板胶合强度和甲醛释放量的影响。结果表明,有机盐与氯化物组合效果最佳,既提高了板材胶合强度,又使甲醛释放量达到E1级要求。组合使用时最佳使用量为:有机盐1％,氯化物1％。     

Structural mechanics of wood composite materials I: Ultrasonic evaluation of internal bond strength during an accelerated aging test

This research attempts to observe indirectly the variation of internal bond characteristics for wood composite materials during accelerated aging test treatment using ultrasonic pulse-transmission techniques. Particleboard (PB) and oriented strandboard (OSB) were the representative specimens. The transit time of the ultrasonic wave propagating through the samples along the nominal length and thickness directions was recorded using an apparatus called PUNDIT (C.N.S. Electronic, London). The transit times were measured in the samples under an oven-dried condition after treating them with boiling water at different treating time stages, and the velocity was then calculated based on the transit time. Examination of the internal bond strength conducted on the same samples was done according to JIS A 5908. A study of the relations among springback, internal bond strength, and velocity indicated that a high correlation existed between ultrasonic velocity measured in the length or thickness direction and the internal bond strength for the PB specimen, but no significant correlation was observed between the velocity measured in the length direction and the internal bond strength for the OSB specimen. The results of this research suggested that ultrasound techniques can be applied to predict or evaluate the internal bond state of some wood-composite materials made of relatively small particles, such as PB especially, during accelerated aging test treatment processes.Part of this paper was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 1997     

Secondary and ternary emulsions from vinyl acetate,N-hydroxymethyl acrylamide,and urea for wood bonding

In this study, N-hydroxymethyl acrylamide (NMA) and vinyl acetate (VAc) were used in order to prepare secondary emulsions; additionally urea was then introduced into the polymerization to form ternary emulsions, adjusting different proportions of the three components. Compared to pure polyvinyl acetate, these two emulsion types presented shorter curing time, improved water resistance, and higher bond strength; this is based on the crosslinking ability introduced by the NMA, enabling such a partial crosslinking already during the polymerization process and during storage. The viscosity, solid content, storage stability, curing and drying behavior, water resistance, delamination time, and bond strength were influenced by the proportions of NMA and urea in the two systems. Urea had a positive effect on the wet bond strength, but a negative effect on the dry bond strength. The proportion of NMA and of urea during the polymerization preferably was 1–2 % based on VAc.     

酯化玉米淀粉乳液的改性

采用羧基丁腈胶乳与酯化玉米淀粉乳液共聚的方法对酯化玉米淀粉乳液进行改性,并通过正交试验得出适宜的反应条件。改性后的共聚乳液胶合干强度可达9.865MPa,湿强度达1.032MPa,可用作API的主剂。