共查询到17条相似文献，搜索用时 171 毫秒
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酚醛刨花板加速老化试验的研究 总被引：2，自引：0，他引：2
刨花板的耐老化性质是它作为建筑用材的一项重要指标。本试验采用人工老化方法，讨论加速老化因素对马尾松酚醛刨花板耐老化能力的影响，并对几种加速老化方法进行分析比较。结果表明：循环数、冷冻、喷蒸、干燥等因素对老化结果有不同程度的影响；不同的加速老化试验方法对刨花板ＭＯＲ、ＩＢ和ＴＳ的影响程度也不相同；可采用热水浸泡－干燥循环法代替ＡＳＴＭＤ１０３７的６循环加速老化试验；可把沸水煮１小时方法作为工厂对产品的耐侯性质量控制法。 相似文献
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采用挤出成型制备了竹粉增强聚丙烯复合材料,研究竹粉/聚丙烯复合材料在紫外加速老化与湿热老化后的力学性能变化与尺寸稳定性.结果表明:在紫外线加速老化200 h后,复合材料的弯曲强度与弯曲模量无显著变化,试件宽度与厚度在紫外加速老化前后也无显著改变;但湿热老化对复合材料的弯曲强度与弯曲模量有显著影响,在沸水中浸泡2h后,复... 相似文献
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论述和分析木质剩余物复合材料老化的原因,主要有木质剩余物的老化、胶粘剂的老化、木质剩余物的回弹和膨胀—收缩应力。综合论述木质剩余物复合材料加速老化试验方法,指出木质剩余物复合材料在加速老化试验方面的研究,适宜采用ASTM D1037六循环加速老化法和老化仪检侧法。分析木质剩余物复合材料老化的影响因素,如温度、湿度、试件尺寸等。 相似文献
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本文研究加速老化试验对脲醛胶刨花板和酚醛胶定向刨花板物理机械性能的影响。结果表明,脲醛胶刨花板经加速老化处理后机械强度降低,吸水厚度膨胀率明显增大,在选用的5个老化试验中,对刨花扳性质影响最大的是APA D—5老化试验;对脲醛胶刨花板进行浸泡、干燥处理,比单一的进行浸泡处理对平面抗拉强度的影响要大得多;加速老化对刨花板MOE的影响比对MOR的大。 相似文献
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稻壳／聚乙烯复合材的自然老化与紫外光加速老化 总被引：4，自引：1，他引：3
对稻壳/聚乙烯复合材的室外自然老化情况进行1年多的观察,并对相同材料进行实验室紫外光(UV)加速老化,研究材料力学性能变化,并通过傅里叶红外波谱(FTIR)分析探讨老化机制,力争寻求二者之间的初步对应关系.自然老化试件在气温较低和日照时间较短的前5个月内(冬季)颜色基本没有变化,经历盛夏之后颜色发生显著变化,变化幅度与实验室加速老化1 500 h的结果相当.与自然老化相比,加速老化500 h后即可明显表现出各种化学特征的变化趋势,但在以后的1 500 h里没有再发生显著变化;而自然老化12个月后试材表面才有显著化学变化.老化首先使稻壳/聚乙烯复合材的颜色发生较大改变,表面化学性质变化也较早开始,但无论自然老化还是加速老化在短时间内对材料力学性能都不会产生显著影响. 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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《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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研究了加速老化试验对经不同装饰后的脲醛胶中纤板物理力学性能的影响.结果表明,未经装饰的中纤板经加速老化处理后力学强度降低较快,吸水厚度膨胀率明显增大.选用的4种装饰中纤板中,三聚氰胺板的力学性能降低最大,油漆板耐久性能最好. 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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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 相似文献
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为研究富阳竹纸的耐老化性能,选取杭州富阳逸古斋元书纸有限公司生产的超级元书、二级元书、冬纸壹号及古籍修复纸这4种富阳手工竹纸进行干热加速老化试验。基于样品的D65亮度、抗张指数、断裂伸长率、表面pH及热稳定性等理化性能指标在老化过程中的变化情况,分析富阳竹纸的耐老化性能。试验结果表明:所有竹纸样品的D65亮度在老化过程中发生了不同程度的下降,其中经过纯碱二次煮料或化学漂白的竹纸,老化前后D65亮度的变化相对较小,即竹纸的D65亮度稳定性与纸浆的处理程度呈正相关。但经过多次煮料和化学漂白的竹纸,其热稳定性在老化后发生小幅度的下降,说明工艺处理程度过大会影响竹纸的热稳定性。强度方面,初始抗张指数较高的竹纸,经老化后仍保留较好的强度性能。在老化过程中,所有竹纸样品的pH均逐渐降低,其中化学漂白竹纸的下降幅度最大,即化学漂白会加速竹纸的酸化。4种富阳竹纸的耐老化性能存在差异:冬纸壹号各方面的性能在老化过程中相对比较稳定,超级元书的各项性能经老化后发生了一定程度的下降,二级元书的强度稳定性和热稳定性能较好,古籍修复纸的D65亮度稳定性最好。 相似文献