共查询到19条相似文献,搜索用时 62 毫秒
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以层板胶合木为研究对象,采用ASTM D1037、BS EN1087-1,CAN/CSA-0188,ASTM D3434四种人工加速老化方法对单组份聚氨酯胶黏剂胶合而成的层板胶合木构件进行处理。老化处理后,试材的胶合剪切强度下降幅度在27.8%~44.9%之间,下降程度明显高于吸水厚度膨胀率、静曲强度和弹性模量,据此建议将胶合剪切强度作为判定层板胶合木构件耐老化性能的指标。BS EN1087-1老化处理后试材的性能变化情况SASTM D1037较为相似,且用时短,认为是研究层板胶合木构件耐久性较优的人工加速老化处理方法。 相似文献
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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。 相似文献
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胶合木层板配置与其强度性能 总被引:3,自引:0,他引:3
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... 相似文献
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《木材工业》2021,(2)
正交胶合木(Cross-laminated timber,CLT)胶层剪切强度是其胶合质量评价的重要指标。依据层板模量(8~12 GPa为低、12~16 GPa为中、16 GPa以上为高)、层数(3、5层)、层板厚度(15、25 mm)、组坯方向(正交和45°)共设置6种组坯方式,按照LY/T 3039—2018《正交胶合木》测试CLT板胶层剪切强度。研究结果表明:胶层剪切的破坏模式主要有沿着木材表面发生锯齿状剪切破坏和沿着横向层层板年轮方向剪切破坏;加载速率对胶层剪切强度影响不显著;除层板厚度对CLT板胶层剪切强度影响不显著外,表层层板模量、层板层数、组坯方向对CLT板胶层剪切强度存在显著性影响。 相似文献
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3种竹材重组材耐老化性能比较 总被引:1,自引:0,他引:1
竹材重组材生产工艺简单、产品性能好、用途广,近年发展迅速。本文采用欧洲标准BSEN1087—1人工加速老化方法对冷压、热压、炭化热压三种工艺生产的竹材重组材进行了耐老化性能测试,并对测试数据进行分析、比较。结果表明:热压炭化竹材重组材老化前后的24h*gt.水率、24h吸水厚度和宽度膨胀率均低于其他两种工艺生产的竹材重组材;热压炭化材与热压材耐老化处理后的弹性模量、静曲强度下降趋势和下降幅度差异不大,冷压材下降幅度最大;3种板材老化过程中内结合强度的变化情况差别不很明显,下降趋势和下降幅度基本一致。 相似文献
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为保证结构安全,提高材料使用寿命,对胶合木耐久性能进行研究。以未经防腐处理与经过CCA防腐处理的2种樟子松制备的胶合木为研究对象,探究湿热沸水老化处理对其耐久性能的影响。研究结果表明:湿热沸水老化处理对CCA防腐樟子松-单组分聚氨酯试件吸水厚度膨胀率的影响更为显著;经老化处理后,樟子松试件的静曲强度、弹性模量和胶层剪切强度较老化处理前均大幅下降,未防腐处理樟子松试件分别下降了45.07%、30.01%和45.07%,CCA防腐樟子松试件分别下降了43.59%、30.35%和50.08%;CCA防腐樟子松试件2次循环剥离总剥离率最高达39.49%,因此不建议使用CCA防腐处理樟子松与单组分聚氨酯胶合生产层板胶合木;SPSS方差分析表明,老化时间和材料种类对试件的上述3种力学性能均具有显著性影响。 相似文献
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短周期工业材层板等级区分与胶合木强度性能之关系宋润惠郝金城高云龙(黑龙江省林产工业研究所1试验目的结构胶合木是通过合理配置不同等级的层板径胶合而成的木质材料,与天然木材相比,它具有较大的规格尺寸和较高的力学强度,尺寸稳定性好,耐久性强。根据建筑设计要... 相似文献
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采用加速老化试验方法对竹复合管材的湿热老化性能及老化机理进行研究,探究不同湿热老化历时下竹复合管材拉伸、压缩和弯曲性能的变化。结果表明,在交变湿热应力作用下,竹复合管材拉伸强度、压缩强度、压缩弹性模量、弯曲强度和弯曲弹性模量随湿热老化时间延长呈幂指数降低,拉伸劣化大于弯曲,弯曲劣化大于压缩,模量劣化大于强度;湿热老化28次后,竹复合管材拉伸强度、压缩强度、压缩弹性模量、弯曲强度和弯曲弹性模量分别降低34.11%、25.64%、26.39%、26.14%和27.83%。交变湿热应力使结构层树脂和竹纤维均发生湿胀,结构层树脂湿胀率小于竹纤维,不均匀的湿胀使结构层树脂受拉、竹纤维受压,结构层树脂竹纤维界面产生剪切力,树脂开裂、脱落,纤维树脂界面形成孔洞和微裂纹降低有效应力传递,当剪切力大于界面粘结力时,界面损伤模式主要表现为脱粘以及剪切分层。 相似文献
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采用两步法工艺和设备,按照9组实验配方,在基础配方的基础上,添加铁红和UV531作为添加剂,制备出亚麻屑/高密度聚乙烯复合材料。分析了加入不同添加剂的复合材料老化前后的弯曲性能、冲击性能和密度。实验数据表明,亚麻屑含量为60%、添加抗老化剂UV531的木塑复合材料物理及力学性能较好,得出了加工亚麻屑/HDPE复合材料的最优工艺和实验配方。 相似文献
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The durability of wood-based panels is one of the most important properties when they are used in residential construction.
The main objectives of this study were to investigate the quantitative relationship between the Wet-bending A test and the
Wet-bending B test, examine the aging effects of the treatments specified in the wet-bending methods, and discuss the relationship
between wet-bending and outdoor aging tests conducted in Shizuoka, Japan. Wet-bending tests, internal bond tests after humidity
treatment, and outdoor aging tests in Shizuoka were conducted using eight types of commercial wood-based panels. A linear
relationship was found between the load-carrying capacity (LCC) from the Wet-bending A test and the LCC from the Wet-bending
B test. The LCC from Wet-bending B could be obtained from LCC from Wet-bending A by multiplying it by 0.9, which may be applicable
as a quantitative ratio of aging effects between the two. LCC for methylenediphenyl diisocyanate-bonded panels recovered to
almost 100% of the initial strength. A certain relationship was found between the LCC after Wet-bending A and the LCC after
a 1-year outdoor exposure in Shizuoka. Internal bond strength showed a good correlation between the JIS-A treatment and the
1-year outdoor exposure treatment. 相似文献
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《Wood material science & engineering》2013,8(1):46-52
Abstract Accelerated aging of spruce wood samples have been carried out by thermo-hydro (TH) treatments. These treatments were applied to accelerate the chemical reactions that take place during the natural aging of wood. In order to avoid dissimilar chemical reactions between the TH treatments and the natural aging, mild temperatures (between 100 and 150°C) have been selected at low relative humidity (RH). The mechanical properties of non-aged, natural aged and accelerated aged spruce wood have been compared. It is apparent that longitudinal Young's modulus of accelerated aged wood increase slightly at the beginning of the treatment and is followed by a reduction. Along the radial direction, Young's modulus remains almost unchanged. On the other hand the radial strength is severely reduced. From these results, the relative radial strength has been fitted on the chemical kinetic law. The rate constant of this law has been calculated and the treatment temperature and wood moisture content have been integrated. Finally this law has been extrapolated to standard climatic conditions in order to predict the loss of strength of old wood by knowing its age and its mean climate history of temperature and RH (ambiance condition). 相似文献
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介绍了日光的分布、木材组分对日光的吸收情况以及木材光老化的机理,并从木材的化学成分、颜色以及微观结构变化等方面,分析了光波对木材性质的影响,为木材及木质材料在室外应用的耐老化性能研究提供参考。 相似文献