刨花板耐老化性能的研究

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。     

刨花板连接性能研究进展概述

前言刨花板的工业化生产始于本世纪初。随着这种新型板材的出现,人们对其应用技术一直不断地进行探索。其中,板材间的连接是一个非常重要的问题,需要根据材料的特性、成品用途、以至艺术效果等方面的要求确定其连接形式。60年代中期以来,以刨花板为基材的现代板式家具的生产得到迅速发展,促使这一领域的研究更加深入。迄今为止,人们对刨花板连接性能与其物理力学性能之间的关系已有了较全面、深入的认识,许多研究成果     

石膏刨花板饰面性能的研究

本研究分别采用刨切薄木、三聚氰胺浸渍纸及PVC塑料薄膜对石膏刨花板进行了饰面装饰试验,并测定了饰面材料与基材的胶合强度。结果表明,石膏刨花板具有良好的饰面性能。     

刨花板耐老化性能研究的进展

刨花板耐老化性能研究的进展龙玲，陈士英（中国林科院木材工业研究所北京１０００９１）刨花板耐老化性能是指板材抵抗外界自然条件如干湿、冷热、霜雾、雨雪和紫外线镭射等的能力，因此要求建筑用刨花板应具有良好的耐老化性能。评定耐老化性能主要有两种方法：自然老化...     

阻燃麦秸刨花板性能的研究

根据麦秸板的特点，选择4种复配的阻燃剂，利用正交试验法进行制板试验，根据氧指数和烟密度指标评价其阻燃性能，同时测定板的各项物理力学性能的变化。结果表明，经过阻燃处理，麦秸板的阻燃能力有明显提高，但一些物理力学性能有所降低；研究还给出了阻燃麦秸板的较佳工艺参数。     

定向结构刨花板吸声性能的研究

采用驻波管法测定定向结构刨花板的吸声系数,分析比较了定向结构刨花板与砖、混凝土吸声性能的差异。结果表明,定向结构刨花板具有良好的吸声性能。     

不同树种对刨花板性能的影响

本文对杨木、烨木、水曲柳三个树种进行了制板试验．并进行了性能比较。结果表明：原料的形态、密度、酸度及树皮含量等都直接影响刨花板的物理力学性能。据此，建议企业根据不同使用要求，进行合理选择。     

Improvement of physical and biological properties of particleboards by impregnation with phenolic resin

Summary Particleboards were treated with a low molecular-weight phenol-formaldehyde resin and their properties were evaluated. Particles were dipped into aqueous solutions of resin or sprayed with resin solutions before spraying the conventional phenol-formaldehyde resin adhesive, or sprayed with a mixture of low molecular-weight resin and the adhesive resin in a single step. Though mechanical properties and dimensional stability of the phenolic-resin-treated boards were affected considerably by the incorporated resin loading (IRL), the methods of treatment did not produce significantly different results. After boiling for 2-hours, the boards treated at 10% IRL retained 80% of their strength values in the dry condition. The internal bond strength increased with increasing IRL values, and the boards with 20% IRL showed twice the value of untreated controls at the same level of board density. Treated particleboards showed a dramatic reduction in the rate of swelling even at low resin loading. Results obtained from accelerated laboratory tests of biodegradation suggested that incorporated resin-solids worked well to enhance decay and termite resistance of particleboards. For a brown-rot fungus, the weight loss was substantially reduced at 15% IRL, whereas attack was suppressed almost entirely even at low resin loadings for the white-rot fungus.     

我国林药、林菌的发展现状及建议

通过对全国林药、林菌发展资料和数据的收集,以及典型省区的调研,总结了全国林菌、林药的发展概况和存在的问题,并从加强政府引导、建设示范基地、建立和完善市场体系、加强科技建设等方面提出建议,为推动全国林药、林菌的健康、稳定、持续地发展提供参考。     

城步苗族自治县常用中草药防病治病调查

城步县位于湖南省西南部,属中亚热带山地气候,自然条件优越,植物资源丰富。城步苗胞由于长期生活,丛山峻岭之中,过去称之为“湿热瘴气”之地,容易生病,所以苗族同胞特别注意利用中草药进行防病治病。此次调查资料表明,城步苗胞常用防病治病的药用植物有110科400种(包括变种),为利用中草药防病治病提供参考。     

Properties of wheat straw particleboards bonded with different types of resin

Wheat straw particleboard bonded with a urea–formaldehyde (UF) resin, usually employed in the manufacture of wood-based particleboards, or with a resin based on epoxidised oil was manufactured using a compression molding machine. The effects of resin type on internal bond strength, flexural modulus, and thickness swelling were examined. The properties of boards using UF resins were poor. Internal bond strength and thickness swelling, linked to adhesion quality, were especially low. The high compatibility between straw particles and oil-based resin was explained in terms of straw surface free energy. In straw, this parameter exhibits a much lower polar component than wood species and leads to higher compatibility with resins based on oil than with water-soluble systems like UF.     

Effects of silane coupling agent level and extraction treatment on the properties of UF-bonded reed and wheat straw particleboards

Urea formaldehyde resin bonded reed and wheat particleboards with a density of 0.7g/cm³ were manufactured from two types of particle: fine and coarse particles. The effects of the silane coupling agent (SCA) level and ethanol-benzene (EB) treatment on the board properties were examined. For SCA, epoxide silane (SiEP) and amino silane (SiNH) were used for reed and wheat particles, respectively. The results are summarized as follows. (1) For both reed and wheat boards, the internal bond (IB) strength and thickness swelling (TS) were significantly improved at up to 5% SCA content, but the effectiveness of treatment kept constant at above 5%. (2) The level of SCA had little effect on the bending strength, especially for the boards composed of coarse particles. (3) EB treatment upgraded both the IB and TS of wheat board significantly. (4) SiEP incorporation improved the IB and TS of reed board significantly, whereas EB treatment was more effective for wheat board. (5) The dimensional stability of both reed and wheat boards under varying humidity could be improved by increasing the level of SCA and by EB treatment. EB treatment was more effective than SCA addition.     

DETERMINATION OF STATIC AND DYNAMIC DIFFUSION COEFFICIENTS OF MOISTURE IN PARTICLEBOARDS

The static and dynamic diffusion coefficients are important coefficients todescribe the moisture transfer processes in particleboard.In this paper,the formula ofculculating the static and dynamic diffusion coefficients were deduced.At first,the staticdiffusion coefficients of four kinds of particleboards were determined by using diffusion cupmethod.The results demonstrated that the static diffusion coefficients parallel to panelsurface were 10-20 times as large as that of perpendicular to panel surface for test boards.To determine both dynamic diffusion coefficients and surface emission coefficients ofmoisture in particleboards in one experimental period,specimens in four different thickness-es of each kind of particleboard were used in the experiment.Then the method ofregression was used and the dynamic diffusion coefficients and surface emission coefficien-ts were determined based on the slope and intercept of the regressive line.     

中草药黄精多酚的提取工艺研究

多酚是植物体内广泛存在的生物活性物质。为提高黄精药用价值,以3年生黄精冻干粉为研究对象,通过单因素及响应面试验,分析乙醇体积分数、液料比、浸提时间及浸提温度对黄精多酚浸提效果的影响。结果表明,当乙醇体积分数为60%,浸提温度为50℃,液料比为52∶1,浸提时间为2 h,每100 g黄精的多酚含量最高1.07 g。     

Upgrading of urea formaldehyde-bonded reed and wheat straw particleboards using silane coupling agents

Reed and wheat straw particleboards bonded with urea formaldehyde (UF) resin were manufactured from two different material configurations (i.e., fine and coarse particles). The board densities were in the range of 0.550–.90g/cm³. The effects of particle size and board density on the board properties were examined. The properties of particleboard produced from fine particles were better than those made from coarse particles. An increase in board density resulted in a corresponding improvement in the board properties. The properties of OF bonded reed and wheat straw particleboards were relatively lower than those of commercial particleboards. Three silane coupling agents were used to improve the bondability between the reed and wheat particles and OF resin. Results of this study indicate that all the board properties were improved by the addition of silane coupling agent. The degree of improvement achieved from each coupling agent was different; epoxide silane was found to be more effective for reed straw particleboard, and amino silane was better for wheat straw particleboard.     

纳米纤维素基吸油气凝胶的制备及性能

以竹粉为原料制备纳米纤维素基体材料,以聚乙烯醇(PVA)为增强相,在酸性环境下采用冷冻干燥法制得PVA/CNFs(纳米纤维素)复合气凝胶;采用三甲基氯硅烷(TMCS)对其进行疏水改性处理,随后将其浸渍到还原氧化石墨烯(r GO)悬浮液中,最终制得疏水型r GO/PVA/CNFs复合气凝胶;通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、拉曼光谱(Raman)、接触角(CA)和吸油性能测试,对所制气凝胶的微观形貌、化学结构、疏水性能及吸油性能进行表征。结果表明:制得的复合气凝胶密度为6.78 mg/cm3,具有均匀的三维网状多孔结构,且孔洞结构表面均被石墨烯片层覆盖;经过TMCS疏水处理后,在气凝胶表面形成疏水层结构。FT-IR和Raman分析表明,TMCS疏水改性处理并未改变PVA/CNFs复合气凝胶的化学结构。经疏水处理后气凝胶与水的接触角为138°左右,吸油倍率为78 g/g左右,且吸附过程迅速,饱油后也能悬浮于溶液表面,便于回收再利用。     

用"系统定向原则"指导沙棘中药的开发与保护

沙棘中药新药的研究开发中如何把传统中医理论与生命活动的本质紧密地联系起来,是沙棘中药产品治疗疾病在理论与临床实践上所面临的一个难点。研究中医理论的整体观与系统论的耗散结构论,以求找到两种理论的吻合点和促进沙棘中药产品现代化的开发。中医整体观把人与外部环境看作为统一的整体,强调“正气内存,邪不可干”,把调整机体内部平衡和机体外部环境放在首位。系统论的耗散结构论,是以物质和能量的补充为条件,认为平衡结构是死的,耗散结构是活的,随时间和空间发生变化,各个要素之间相互作用自组织活动。两种理论吻合点在于统一揭示了一个规律,即机体的自我调控是实现自组织活动,保持机体结构与功能的统一,保持机体稳定的动态平衡,正是生命活动的本质。应用这一理论,筛选出适当的药物功效成分,使之与相干组织细胞产生特异性反应使药物“系统定向”并作为一种负熵流,流人机体之中,激活或促进机体自主调节功能的恢复。使机体受疾病干扰发生的扰动恢复有序状态,恢复自组织的相关作用。这种“系统定向”的研究与开发,要求阐明药物在体内的作用的靶点,药物的吸收,转运以及代谢机制,是沙棘中药研究开发的一种基本方法,也利于中药专利产品的保护。