杉木UF浸渍材过热蒸汽干燥—高温热处理特性研究

发布时间：2018-03-16 11:39

  本文选题：过热蒸汽　切入点：干燥　出处：《中南林业科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：针对杉木材质松软、密度和强度低、高附加值利用困难等缺陷,本研究以改性UF树脂浸渍杉木为研究对象,采用过热蒸汽对其进行快速干燥和高温热处理,系统研究了杉木浸渍材的干燥特性和高温热处理特性,获得了优化的干燥和热处理工艺。研究结果能为杉木浸渍改性材的工业化高效干燥和高温热处理,甚至是速生杉木的高附加值利用提供参考和借鉴。本研究的主要研究结论如下:(1)获得了 UF树脂改性杉木的常规干燥基准。采用百度试验法对UF树脂改性杉木进行干燥处理,研究了干燥过程中改性材的初期开裂、内裂和截面变形的发生、发展情况,确定了其干燥缺陷等级和初步干燥基准,并通过中试试验获得了优化的常规干燥基准。(2)探明了 UF树脂改性杉木的过热蒸汽干燥特性。与常规干燥相比,过热蒸汽干燥具有明显的速度优势,且随着干燥介质温度的升高,干燥速率明显增加,当过热蒸汽温度从120℃升高到150℃,干燥速率提高了 75%;过热蒸汽干燥处理对杉木浸渍材颜色影响不明显,当介质温度从120℃升高到150℃,杉木浸渍材明度平均减小2.28%,红绿指数平均减小5.74%,黄蓝指数平均减小4.01%,色差指数平均减小2.55%。(3)揭示了 UF树脂改性杉木的高温热处理特性。高温热处理对木材颜色、尺寸稳定性和力学强度的影响显著。当热处理温度从160℃升高到220℃,试件明度降低11.08%-67.17%,红绿指数降低1.80%-17.30%;随着处理温度的提高和时间的延长,木材平衡含水率降低,尺寸稳定性增加;与对照材相比,高温热处理材的平衡含水率降低3.25%-37.84%,体积湿胀率、径向湿胀率和弦向湿胀率分别减少9.20%-49.70%、2.56%-43.85%、5.56%-44.45%;杉木浸渍材的抗弯弹性模量(MOE)和强度、顺纹抗压强度、横纹全部和局部抗压比例极限应力均呈下降趋势,抗弯弹性模量下降1.0%-11.4%,抗弯强度下降8.2%-65.1%,顺纹抗压强度下降2.7%-17.3%,横纹全部弦向和径向抗压比例极限应力分别下降3.0%-60.9%、11.2%-59.6%,横纹局部弦向和径向抗压比例极限应力分别下降0.43%-36.5%、0.87%-56.5%。高温热处理对木材结晶区没有明显影响,但高温热处理对杉木浸渍材木材结晶度的影响明显。高温热处理对木材燃烧过程中的热释放总量(THR)影响不大,木材在燃烧过程中质量损失与热量释放是同步的,浸渍-热处理材的第二发烟峰与素材相比发烟量大大降低,高温热处理后木材燃烧过程的CO浓度增加,对木材燃烧过程CO2浓度的影响不明显。
[Abstract]:Aiming at the defects of Chinese fir wood, such as soft material, low density and strength, difficulty in using high added value, the modified UF resin impregnated Chinese fir was used as the research object, and superheated steam was used for rapid drying and high temperature heat treatment of the modified UF resin impregnated Chinese fir. The drying characteristics and high temperature heat treatment properties of Chinese fir impregnated wood were studied systematically, and the optimized drying and heat treatment technology were obtained. The main conclusions of this study are as follows: (1) the general drying benchmark of UF resin modified Chinese fir was obtained. The UF resin modified Cunninghamia lanceolata (Cunninghamia lanceolata) was treated by Baidu method. The initial cracking, internal crack and cross section deformation of the modified wood during the drying process were studied, and the drying defect grade and the preliminary drying criterion were determined. The superheated steam drying characteristics of Chinese fir modified by UF resin were investigated through the pilot-scale test. Compared with conventional drying, superheated steam drying has obvious speed advantage. With the increase of the temperature of drying medium, the drying rate increased obviously. When the superheated steam temperature increased from 120 鈩，

本文编号：1619757