脲醛树脂生产中的反应终点控制

作为胶粘剂使用的脲醛树脂,其终点控制决定着产品的物理力学性能,准确地控制反应终点,就能制出好的产品来。而要准确地控制反应终点,首先要选择好的控制方法。本文将对脲醛树脂生产中通常使用的终点控制方法作一简单介绍,并就控制方法提一点个人认识供同行参考。     

AH型非贵金属催化松香歧化反应动力学研究

用AH型非贵金属催化剂催化松香歧化反应,考察了搅拌速率、催化剂粒度、反应温度、反应时间对反应的影响,建立了动力学方程。确认在240~270℃范围反应为一级,求出在240、250、260和270℃时的反应速率常数分别为2.9×10-3、3.1×10-3、1.42×10-2和2.51×10-2min-1。表观活化能E为184.80×103kJ/mol,频率因子A=1.453×1016。     

氯化亚铜催化的月桂烯氢氯化反应的研究(Ⅲ)——烯丙基型氯化物的酯化反应

研究月桂烯氢氯化反应产物中里哪基氯、香叶基氯和橙花基氯３种烯丙型氯化物与醋酸钠的酯化反应。重点考察了催化剂、反应温度和氯化物组成对酯化反应产物分布的影响。结果表明：（１）在氯化亚铜催化剂存在下，３种烯丙基型氯化物与醋酸钠在醋酸溶剂中均可转化成醋酸里哪酯，酯化反应选择性达９６％以上；（２）在三乙胺催化剂存在下，３种烯丙基型氯化物与醋酸钠反应可转化成相应的醋酸酯，但里哪基氯酯转化生成醋酸里哪酯的选择性明显低于香叶基氯和橙花基氯，且伴随有消除副产物生成；（３）低温有利于醋酸里哪酯的生成，温度升高有利于醋酸里哪酯向醋酸香叶基酯和醋酸橙花酯的生成；在优化反应条件下，醋酸里哪酯的选择性达９６．５％。     

氯化亚铜催化的月桂烯氢氯化反应的研究（Ⅲ）：烯丙基型氯化物的…

研究月桂烯氢氯化反应产物中里哪基氯，香叶基氯和检花基氯３种烯珍型氯化物与醋酸钠的酯化筢应，重点考察了催化剂，反应温度和氯化物组成对酯化反应产物分布的影响。结果表明：１．在氯化亚铜催化剂存在下，３种烯丙基型氯化物与醋酸钠在醋酸溶剂中均可转化成醋酸里哪酯，酯化反应选择性达９６％以上；２．三乙胺催化剂在下，３种烯丙基型氯化物与醋酸钠反应可转化成相应的醋酸酯，但里哪基所氯醋转化生成醋酸里哪酯的选择性明显低     

脲醛树脂反应终点控制对刨花板施胶量的影响

笔者根据多年的实验经验，提出控制好脲醛树脂制造工艺中的反应终点，可有效地改善脲醛树脂的性能，并可在保证刨花板主要物理力学性能指标合格的前提下，减少施胶量，降低生产成本。     

建筑结构近似非线性反应分析方法综述

本文较详细地总结和评述了5种建筑结构的近似非线性反应分析方法。通过总结和评述,可系统地了解现有这些方法的原理和过程,以供建筑结构的研究人员和设计工作者使用时参考。     

芒草热解焦的制备及其CO2气化反应动力学及机理分析

利用傅里叶红外光谱仪、扫描电镜和低温氮吸附法表征芒草热解焦的物化特性,采用非等温法和主曲线法结合研究芒草热解焦CO_2气化反应机理。结果表明:随着制备温度的升高,芒草热解焦的有机质减少;热解过程有利于孔隙结构的形成,增大了热解焦比表面积和孔容,600℃时芒草热解焦(MPC600)的微孔率最大,为86.73%;随着制备温度和气化升温速率的升高,芒草热解焦气化反应的最大失重速率温度向高温侧偏移。采用Ozawa法对芒草热解焦气化动力学参数进行计算,制备温度为400、600和800℃的芒草热解焦平均活化能分别为171.87、181.20和184.45 kJ/mol;所有制备温度下获得的芒草热解焦的活化能与转化率无关,反应可用单一的动力学机理函数描述。主曲线法判定动力学模型机理函数结果表明:芒草热解焦气化动力学符合一维相边界反应(R_1)机理。     

SJ-75型食用菌培养料搅拌机的研制

随着林区天然林保护工程的实施和木材采伐量的日益减少，食用菌的生产已被愈来愈多的林区人所认识。在送科技下乡和科研调查过程中，我们发现仍有大部分食用菌栽培户使用铁锹人工搅拌培养料。人工搅拌培养料劳动强度大，生产效率低，搅拌效果差。为了满足广大食用菌栽培户的生产需求，我们研制了制作容易、操作简便，适用性强的SJ-75型食用菌培养料搅拌机。     

浅谈MR417型带锯机压辊技术

压辊是ＭＲ４１７型带锯机的关键配件，它直接影响着制材的质量，该就压辊技术作以探讨。     

菜籽油裂解燃料离子液体催化酯化反应降酸工艺的研究

为了降低裂解燃料酸值,增加燃料的稳定性能,将吡啶丁烷磺酸硫酸氢盐应用于菜籽油裂解燃料的酯化反应。考察了催化剂用量、反应时间和反应温度等对酸值的影响,并在最佳优化条件下考察了裂解燃料成品的理化性质。结果表明:吡啶丁烷磺酸硫酸氢盐对催化酯化反应具有很高的催化活性。优化工艺条件为:催化剂用量1.2%、反应温度75℃、反应时间70 min,在此工艺条件下,酸值降低到1.0 mgKOH/g以下。     

Dependence of reaction kinetics and physical and mechanical properties on the reaction systems of acetylation I: reaction kinetic aspects

The dependence of the reaction parameters of acetylation on the reaction mixture was compared among uncatalyzed, acetic anhydride-xylene mixed, and acetic anhydride-pyridine mixed solutions. Wood meal and blocks were used to examine the effect of sample size. A first-order rate equation was applied to the data, and a rate constant and leveling off value of weight gain (WG) were estimated. The rate-determining step was examined from the viewpoint of activation energy. The results were as follows: (1) Regarding the magnitude of the rate constant, the order was pyridine system > uncatalyzed system > xylene system. (2) The ultimate value of WG was lower in the uncatalyzed and xylene systems than the pyridine system, probably because of the swelling ability of pyridine. (3) The activation energies of acetylation estimated for wood meal were 120, 135, and 110kJ/mol for the uncatalyzed, xylene, and pyridine systems, respectively. (4) The characteristics of the diffusion-controlled reaction became marked when the acetylation was carried out in the pyridine system, at elevated temperature, and for wood blocks. Under these conditions, the supply of reagent to the reaction site might not be sufficient to fuel the reaction.Part of this report was represented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002     

葡萄SSR反应体系的优化

以葡萄新鲜幼嫩叶片为材料,研究了SSR分析过程中的影响因素,包括Taq酶、Mg2 、dNTP、引物、模板DNA浓度、退火温度等,建立了适合葡萄SSR反应的PCR体系,即20μl反应体系中含有Taq酶1.0 U、Mg2 浓度为1.5 mmol/L,dNTP 0.2 mmol/L,引物0.5μmol/L,模板DNA20~30 ng。扩增程序为:95℃预变性4 min;95℃变性50 s、50~60℃退火1 min7、2℃延伸1 min 30 s,30个循环;最后72℃延伸7 min。     

Non-uniform reaction of solid wood in vapor-phase acetylation

To clarify the non-uniform reaction of wood during vapor-phase acetylation, spruce wood blocks were exposed to acetic anhydride vapor at 120°C. Weight percent gain (WPG) due to the acetylation was estimated from the equilibrium moisture content at 25°C and 60% relative humidity. The diffusion of reagent vapor was much faster along the longitudinal direction than along the tangential direction. When the end surface was exposed to the reagent vapor for 48?h, 20% WPG, which was known to have sufficient stability and durability, was achieved to a depth of 42.5?mm. However, this depth was only 6.5?mm when the straight-grain surface was exposed. The reaction profiles were successfully approximated using reaction time (t), reaction rate (k′), delay time (t _d′), and a parameter n reflecting the diffusion-controlled reaction. The t _d′ value increased almost linearly as the depth increased from the surface. The k′ value ranged from 0.02 to 0.03?h^?1, regardless of the depth and direction of diffusion. The n value decreased with an increase in the depth and approached 1–2. These values enabled the prediction of the degree of acetylation at any reaction time and positions of wood during vapor-phase acetylation.     

关于降低林用烟剂农药反应温度的探讨

烟剂农药使用方便,成本低,效果好,但烟剂燃烧结束后,因其反应温度过高,易起明火,从而引发森林火灾。如何降低烟剂的反应温度,是各国研究的重点。文章通过烟剂的组成成分及其特性,氧化剂与燃烧剂的合理配比、最高反应温度的计算,降低烟剂反应温度的技术措施几个方面进行了阐述,提出了解决办法。     

Color development of proanthocyanidins in vanillin-hydrochloric acid reaction

The influence of proanthocyanidin (PA) structures contained in bark on color development in the vanillin-hydrochloric acid (V-HCl) method used widely as a quantitative method for measuring PA were examined. The maximal absorption wavelength was different in terms of the bark from which the PA was obtained. Phenyl nucleus (resorcinol, phloroglucinol) constituting the A-ring of PA reacts with vanillin to produce the color. The maximal absorption wavelengths of the solutions from synthesized procyanidin and profisetinidin were 500 and 540 nm, respectively, indicating that the color tone differs in the V-HCl method based on the hydroxylation patterns of the A-ring. The colored solution of (+)-catechin with vanillin was dialyzed, and the resulting product (C-VC) was analyzed by gel permeation chromatography and ¹H nuclear magnetic resonance. It was found that C-VC was a polymer complex consisting of 9mol (+)-catechin moieties and 10mol vanillin moieties. It was presumed that the cationized vanillin molecules that do not combine with (+)-catechin play an important role on color development in the presence of C-VC.This study was presented at the 44th and 45th Annual Meetings of The Japan Wood Research Society, Nara and Tokyo, April 1994 and April 1995     

Analysis of progress of oxidation reaction during oxygen-alkali treatment of lignin 2: significance of oxidation reaction of lignin during oxygen delignification

The progress of lignin oxidation during oxygenalkali bleaching of pulp was evaluated by the method based on the difference between permanganate consumption of original pulp and that of the mixture of pulp and effluent after oxygen-alkali bleaching. By low-consistency oxygen bleaching of softwood kraft pulp, the permanganate consumption decreased very little. When the kappa number of the pulp was halved (from 25.4 to 13.4), the decrease in permanganate consumption of 1 g pulp was only 1.22ml of 0.02mol/l potassium permanganate. This value was smaller than that obtained for the oxygen-alkali treatment of a corresponding amount of isolated residual lignin, 6.40ml. This was not due to the slow oxidation of lignin in pulp but to the formation of permanganate-consuming substances from carbohydrates. Those newly formed substances cannot be oxidized by oxygen-alkali treatment. Taking these facts into account, lignin originally present in pulp was found to be oxidized well. Reduction of carbonyl groups in carbohydrates prevented the formation of such substances.Part of this paper was presented at the 10th ISWPC, Yokohama, June 1999; and at the 43rd Lignin Symposium, Fuchu, October 1998     

麻疯树ISSR-PCR反应体系的建立和优化

以2年生的麻疯树嫩叶提取的DNA作为模板,固定ISSR-PCR扩增程序,对影响PCR扩增的模板DNA、dNTP、引物、TaqDNA聚合酶以及Mg^2＋浓度等5因素（不同水平）进行单因素设计优化,得到适合于麻疯树ISSR-PCR扩增的体系为：25μL反应体系中,含模板DNA300 ng、dNTP 0.15 mmol/L、引物0.20μmol/L、TaqDNA聚合酶1.0 U及Mg^2＋3.0 mmol/L。     

竹子SRAP-PCR体系的建立与优化

首次报道竹类植物SRAP-PCR反应体系的建立与优化。以竹叶总DNA为模板,经过大量实验,建立和优化了竹子SRAP-PCR的50μL反应体系,20 ng模板DNA,2.0 mmo1/L Mg2+,175μmol/LdNTPs,0.2μmol/L引物,1.5 UTaqDNA聚合酶,5μL10×buffer,退火温度52℃为最优反应组合。该反应条件下扩增条带清晰,多态性丰富。     

白桦SRAP-PCR反应体系的优化

采用单因素试验对白桦SRAP-PCR反应体系中的5个因素(Mg2+、d NTP、引物、Taq DNA聚合酶和模板DNA)进行优化,结果表明:在25μL反应体系中Mg2+浓度2.0 mmol·L-1、Taq DNA聚合酶1.5 U、d NTPs 0.15 mmol·L-1、引物浓度0.4μmol·L-1、模板DNA 30 ng,该体系能够很好地满足白桦SRAP扩增的要求。优化体系的建立将为今后利用SRAP标记技术对白桦进行分子遗传育种研究奠定基础。