共查询到17条相似文献,搜索用时 93 毫秒
1.
介绍了气候老化因素对室外用木质人造板老化性的影响机理, 以及各种室内加速老化法在国内外的研究应用现状; 针对现行室内加速老化方法中存在的问题, 提出改进方法, 并对系统性加速老化方法的应用前景进行探讨。 相似文献
2.
3.
4.
以层板胶合木为研究对象,比较了不同人工加速老化方法(ASTM D1037、BS EN1087—1、CAN/CSA—0188、ASTM D3434)对层板胶合木构件力学性能的影响。层板胶合木构件在4种不同人工加速老化方法的作用下,通过对静曲强度、弹性模量、剪切强度及木破率等实验指标的比较分析,发现试材的胶合剪切强度下降程度明显高于其他性能的变化程度,建议作为判定层板胶合木构件耐老化性能的重要指标;经分析认为达到相同老化效果BS EN1087—1法更节约时间,是研究层板胶合木耐老化性能较优的人工加速老化处理方法。 相似文献
5.
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
6.
前言传统的人造板(本文专指刨花板或中密度纤维板)生产需施加一定量的合成树脂胶将刨花或纤维材料粘结成板。对于室内用的人造板产品主要添加脲醛树脂胶,而对室外用或结构用的人造板产品则以添加酚醛树脂胶为主。由于人造板生产对胶料的依赖性,使人造板生产的发展受到化工原料供应和价格的制约,尤其自七十年代初世界“石油危机”以来,胶料的供应和价格一直是世界各国人造板生 相似文献
7.
给出了对中密度纤维板、胶合板等人造板材进行室外自然老化性能试验数据,即通过对放置在室外1 ̄2年的上述人造板材和各项物理力学性能的测试,进一步分析了室外自然老化对人造板材物理力学性能方面的影响及其产生原因,这项试验对今后人造板的生产与使用等方面,都具有十分重要意义。 相似文献
8.
9.
10.
简述了我国室外人造板产品发展概况及重要性能检测,从区域、性能检测和人造板种类三个方面比较分析了国内外对室外人造板重要性能的相关检测标准,阐述了我国现有室外人造板标准存在的不足,提出应尽快制定适合我国室外人造板产品的较为系统的检测方法标准体系。 相似文献
11.
Evaluating the durability of wood-based panels using internal bond strength results from accelerated aging treatments 总被引:1,自引:0,他引:1
In this study, the durability of wood-based panels was evaluated by comparing the internal bond (IB) strength retention after
five different laboratory-based accelerated aging tests with the IB retention after 5 years of outdoor exposure in Shizuoka
City. In each accelerated aging test, the IB retention of MDI-bonded panels showed high retention compared to other panels.
Outdoor exposure in Shizuoka City resulted in an IB retention value for particleboard (PF) and oriented strandboard (aspen)
of less than 10% after the 5-year exposure period. Medium-density fiberboards maintained their initial IB strength over the
same period. Calculation of the mean IB retention for all board types allowed comparison of the severity of aging between
the accelerated test methods and outdoor exposure. The ASTM six-cycle test method was the most severe among the standard treatment
cycles applied. 相似文献
12.
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
13.
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
14.
15.
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
16.
P. Luner 《Wood Science and Technology》1988,22(1):81-97
Summary The thermal stability of papermaking pulps under conditions of accelerated aging and at pyrolytic temperatures was examined. Degradation was found to be extremely complex and influenced by both the technical processes of papermaking and by the experimental methods used. At moderate temperatures, as used for accelerated aging, the folding endurance test was found to be a sensitive measure of degradation. Methods of reducing the variability of the test were considered, and a new technique capable of handling widely different results was developed and evaluated.Several papermaking pulps were artificially aged and the resultant loss of strength attributed to the interaction between a gradual fiber strength reduction and a rapid increase in interfiber bonding. Excessive initial inter-fiber bonding decreased handsheet stability. Softwood sulfite and kraft pulps were more stable than a birch kraft pulp, but the behavior of sulfite pulps varied greatly. The presence of lignin or a high hemicellulose content was not of itself sufficient to cause rapid aging.The pyrolytic behavior of pulps was investigated using thermogravimetric analysis. Papermaking pulps had mean pyrolytic activation energies between 30–45 kcal/mole. The activation energy decreased as the reaction proceeded. Correlation of these activation energies with the rate of loss of physical properties during accelerated aging was not good. The results indicated that the rate determining reactions for pyrolysis and for low temperature degradation are different but that the pyrolytic behavior is partially determined by the supramolecular structure. Empirical stability indices, based on both the integral and differential thermograms, were calculated, and these correlated well with the relative rates of loss of physical properties.A large part of this paper is based on the thesis of R. D. Carwell. Contributions were also made by L. Lyon and M. C. Varshney. This work was partially funded by the National Bureau of Standards 相似文献
17.
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