木质素基酚醛树脂胶黏剂研究进展

在经过处理改性后,木质素可部分替代苯酚,用于生物基酚醛树脂胶黏剂的制备,降低胶黏剂生产成本,同时能够实现生物质的高效利用,促进循环经济.综述了目前木质素活化改性制备酚醛树脂胶黏剂的最新研究进展,重点介绍了化学改性、物理改性及生物改性等提高木质素反应活性的主要改性方法,对比了不同改性方法合成的木质素基酚醛树脂胶黏剂性能.     

改性淀粉胶黏剂的研究概况及展望

淀粉以其绿色环保的优点在胶黏剂领域中的应用占有举足轻重的地位,但是单一的淀粉胶黏剂有很多不足之处。满足不了各个领域的多方面需求,因此在一定条件下经过物理、化学或者生物方法对其进行有限度的改性,研制出了各种具有优良性能的改性淀粉胶黏剂并且在各个领域中都有很好的推广应用。根据淀粉胶黏剂在改性方面的研究和开发概况,综合介绍了几种改性淀粉胶黏剂的产物性能及其在包装行业中的推广应用情况,最后指出了淀粉胶黏剂改性的优势及未来发展的方向。     

天然胶黏剂的研究进展

天然胶黏剂具有来源广泛、无毒、粘接速度快及制备简单等优点,但粘结力差、提取成本高及使用周期短等问题一直限制着该类胶黏剂的发展.综述了几种重要的天然胶黏剂如单宁胶黏剂、淀粉基胶黏剂、木质素基胶黏剂、植物蛋白胶黏剂等在多个领域的改性研究及应用现状,列举了几种简单的工艺配方,指出了各种天然胶黏剂的发展瓶颈,提出了改进建议和发...     

聚合物基仿生医用胶黏剂的开发与发展应用

在皮肤、内脏、心血管、骨和软/硬组织伤口的再生修复方面,医用胶黏剂具有广泛的应用需求。但在人体内潮湿环境中,生物医用胶黏剂的黏附力较弱是临床上一直面临的挑战。为此,从物理、化学以及生物角度出发,通过模拟自然界中各种动、植物的黏附机制,各种聚合物基仿生医用胶黏剂得到了研发与应用,有效解决了潮湿环境中黏附力较弱的问题。文章总结了各种聚合物基仿生医用胶黏剂的黏附机制及其在创口黏合、止血及软/硬组织再生修复中的应用,并展望了医用胶黏剂的未来发展方向。     

木质素及其衍生物在木材胶黏剂中应用研究进展

以天然可再生资源替代传统化石资源开发绿色环保、性能优异的木材胶黏剂是人造板行业研究的热点。木质素来源广泛、价格低廉,且分子结构中含有羟基、甲氧基、羧基等活性基团,易于功能化修饰,是合成木材胶黏剂的理想原料。本文重点综述了木质素及其衍生物在酚醛树脂、脲醛树脂、环氧树脂、聚氨酯等合成树脂木材胶黏剂中的应用与研究现状,介绍了化学改性、降解、溶剂分级纯化等预处理方式对木质素化学反应活性及合成树脂胶黏剂力学性能的影响,探讨了木质素基木材胶黏剂目前发展面临的困难和挑战,并展望了未来应用及研究方向,以期为木质素资源的高效、高值化综合利用及高性能生物基木材胶黏剂的开发提供理论与技术参考。     

生物油淀粉胶黏剂固化特性研究

生物基胶黏剂拥有环境优良且可再生等方面的特点,在使用方面应用较为广泛。在分析生物油淀粉胶黏剂时,对其固化过程中的热行为、固化反应、固化工艺等方面进行了探讨,并有效运用了复合固化剂和单一固化剂胶黏剂热行为,可从中发现复合固化反应热较大,且固化特征温度较低,其复合固化剂体系固化更为充分有效。文章主要分析了生物油淀粉胶黏固化特征,旨在进一步推动胶黏剂固化。     

陶瓷用胶黏剂的研究现状

胶黏剂在陶瓷的修复、生产和连接等许多方面起着重要的作用,综述了陶瓷用胶黏剂的研究现状,在简要介绍陶瓷结构性能的基础上,重点介绍了应用于陶瓷领域的磷酸盐类胶黏剂、硅酸盐类胶黏剂、氧化物类胶黏剂等无机胶黏剂和环氧树脂胶黏剂、酚醛树脂胶黏剂、丙烯酸脂类胶黏剂等有机胶黏剂近年来国内外的研究情况,以促进陶瓷用胶黏剂的发展。     

我国环保胶黏剂的现状及发展趋势

阐述了环保型胶黏剂将成为胶黏剂市场的主旋律。从使用环境、居住环境、地球环境及资源几个方面论述了发展环保型胶黏剂的目的意义，介绍了目前市场上最常用的三类环保型胶黏剂即热熔型胶黏剂、无溶剂型胶黏剂、水基型胶黏剂的现状，并对水基胶黏剂的种类及应用情况作以详细说明。在建筑、包装、运输等领域，水性胶黏剂得到了广泛的应用。随着人们对环保问题的日益重视，胶黏剂从溶剂型向环保型的转变已成为必然。     

大豆蛋白胶研究进展

大豆蛋白胶作为一种生物基胶黏剂和环境友好型材料逐渐成为研究热点,对近年来的主要研究情况进行归纳和总结,探讨了大豆蛋白胶黏剂的研究方向和发展趋势,针对其发展方向和存在问题进行展望。     

大豆蛋白复合胶黏剂的研究进展

综述了国内外大豆蛋白复合胶黏剂的制备方法,包括大豆蛋白-PF、大豆蛋白-UF胶黏剂和大豆蛋白-丙烯酸酯复合胶黏剂的制备方法,及大豆蛋白复合胶黏剂制备中大豆蛋白表面的改性,着重对目前最常用的硅烷偶联剂和偶氮类化合物两种修饰方法进行了介绍。还介绍了大豆蛋白复合胶黏剂在人造板、造纸等工业领域中的应用,并对复合材料的应用前景进行了展望。     

苯酚液化落叶松全树皮胶粘剂的制备

树皮是一种丰富的可再生天然高分子材料,随着石油资源的日趋短缺,研究并合理利用树皮制备高分子材料具有积极意义。首先在复合酸存在下采用高温苯酚液化法将落叶松全树皮进行液化处理,然后以此作为部分苯酚的替代物,制备耐水环保型树皮胶(即苯酚液化落叶松全树皮-甲醛胶粘剂)。重点研究了不同加碱次数对树皮胶主要性能的影响。结果表明:加碱次数对树皮胶的理化性能影响较大;采用2次加碱工艺制成的树皮胶具有相对最好的综合性能,其胶接性能及游离甲醛释放量均与纯酚醛树脂(PF)胶相当;苯酚液化落叶松全树皮对苯酚的替代量达到30%,但所得系列树皮胶的储存期较短。     

Coconut-fiber-reinforced thermosetting plastics

Thermosetting plastic composites have been prepared with phenol–formaldehyde resins as well as unsaturated polyesters as binders and coconut hair as fibrous reinforcement. Using resole-type phenol–formaldehyde resins, the effect of coconut fiber pretreatment by NaOH, the precondensation time of the impregnated fibrous press material, the resin–fiber ratio, and pressing parameters have been studied. Especially advantageous press-material has been obtained using 60–65 wt % linear novolac type phenol-formaldehyde resin as binder and 35–40 wt % of coconut hair. Applying unsaturated polyester (UP) as binder, BMC (bulk molding compound)-type press material can be prepared using coconut fiber reinforcement instead of glass fibers. To achieve better coupling between coconut fiber and UP matrix, coconut fiber was pretreated by NaOH and/or gamma-preirradiation. It has been found that in glass-fiber-reinforced UP press materials a significant part of glass fiber could be changed for short-cut coconut fiber.     

高替代率竹焦油酚醛树脂的合成工艺研究

竹焦油是竹炭产业的副产物之一,富含酚类物质,可部分替代昂贵苯酚合成竹焦油酚醛树脂(BPF)。以n(苯酚)/n(甲醛)、竹焦油替代率、n(NaOH)/n(苯酚)和反应时间为试验因素,以BPF的黏度和游离酚含量、相应胶合板的胶接强度和甲醛释放量为考核指标,采用正交试验法优选合成高替代率环保型BPF的最佳工艺条件。结果表明:当n(苯酚)/n(甲醛)=2.0、竹焦油替代率为50%、n(NaOH)/n(苯酚)=0.35和反应时间为60 min时,由BPF胶粘剂压制而成的胶合板,其胶接强度和甲醛释放量分别达到GB/T 9846.3—2004标准中Ⅰ类胶合板和E0级的指标要求。     

The chemistry and development of tannin-based adhesives for exterior plywood

Condensed tannins are phenolic in nature and undergo reaction with formaldehyde to form resins. Tannin/formaldehyde condensates tend to have a low degree of condensation resulting in bonds lacking strength and water resistance. Small amounts of short-length phenol/resorcinol/formaldehyde, phenol/formaldehyde, and urea/formaldehyde polymers are used to increase the degree of polymerization of tannin-formaldehyde resins, decreasing brittleness and increasing water resistance. Furfural is used to plasticize tannin/formaldehyde resins to improve the distribution of stress forces on the glueline, overcoming weakness due to stress concentration. Exterior plywood panels were prepared using these modified tannin/formaldehyde resins as adhesives. The modified tannin/formaldehyde adhesives perform well, have similar characteristics to and are as easy to use as phenol/formaldehyde adhesives, and also have a few advantages, especially tolerance to faster pressing times.     

Kinetics of hydroxymethyl phenols formation by in‐line FTIR spectroscopy

The kinetics of phenol–formaldehyde prepolymers catalyzed by sodium hydroxide at various temperatures was studied. Several reactions were conducted with different phenol to formaldehyde as well as phenol to sodium hydroxide molar ratios. The React‐IR system was used to monitor the reaction as well as to determine residual free phenol and formaldehyde. The changes in the concentrations of phenol and formaldehyde with the reaction time were determined. The value of the concentration of the hydroxide ion, [OH^?], was obtained by measuring the pH value of reaction mixture. The concentration of the hydroxide ion, [OH^?], expressed as a function of reaction time, was fitted by the six‐order polynomial to the experimental data. On the basis of the proposed reaction scheme the kinetic model was developed. The kinetic parameters were obtained by adjusting the experimental evolution of phenol and formaldehyde during the synthesis. Using this method the changes in the concentrations of five species of hydroxymethyl phenols with the reaction time was also been calculated. The activation energy and preexponential factor have been calculated for individual reactions. The accuracy of the kinetic model was confirmed by comparing experimental concentration profiles of formaldehyde and phenol with the calculated ones for different molar ratios. The experimental tendencies are in agreement with the results of the model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Electrospun porous carbon nanofibers derived from bio-based phenolic resins as free-standing electrodes for high-performance supercapacitors

Phenolic resins were employed to prepare electrospun porous carbon nanofibers with a high specific surface area as free-standing electrodes for high-performance supercapacitors. However, the sustainable development of conventional phenolic resin has been challenged by petroleum-based phenol and formaldehyde. Lignin with abundant phenolic hydroxyl groups is the main non-petroleum resource that can provide renewable aromatic compounds. Hence, lignin, phenol, and furfural were used to synthesize bio-based phenolic resins, and the activated carbon nanofibers were obtained by electrospinning and one-step carbonization activation. Fourier transform infrared and differential scanning calorimetry were used to characterize the structural and thermal properties. The results reveal that the apparent activation energy of the curing reaction is 89.21 kJ·mol^–1 and the reaction order is 0.78. The activated carbon nanofibers show a uniform diameter, specific surface area up to 1100 m²·g^–1, and total pore volume of 0.62 cm³·g^–1. The electrode demonstrates a specific capacitance of 238 F·g^–1 (0.1 A·g^–1) and good rate capability. The symmetric supercapacitor yields a high energy density of 26.39 W·h·kg^–1 at 100 W·kg^–1 and an excellent capacitance retention of 98% after 10000 cycles. These results confirm that the activated carbon nanofiber from bio-based phenolic resins can be applied as electrode material for high-performance supercapacitors.     

酚醛树脂热降解动力学研究

用热失重非等温法对不同甲醛,苯酚魔鬼洋比的酚树脂进行了热降解动力学研究。结果表明,甲醛,苯酚摩尔比为１．５时,酚醛树旨的热发活化能最高。耐热性最好。     

Using Renewables in Panelboard Resins to Influence Volatile Organic Compound Emissions from Panels

Technical lignin and condensed tannins have been combined with soy flour as model of no-added-formaldehyde adhesive binders for veneer wood products to understand their impacts on volatile organic compounds (VOCs) produced during panel manufacture. VOC emissions captured on manufacturing lauan hardwood plywood at 170?C were dominated by acetaldehyde, hexaldehyde, acetone, and terpenes in both the condensate and gaseous fractions of press emissions. Other aldehydes including formaldehyde, valeraldehyde, and propionaldehyde were produced in relatively lower quantity during panel manufacture. Compared to using soy flour alone, lignin, and tannin reduced the formaldehyde and acetaldehyde contents in press emissions. These reductions in VOCs had a dependency on adhesive resin pH with an alkaline formulation proving to also decrease longer chain aldehydes such as valeraldehyde and hexaldehyde. Chamber testing plywood panels found the composition of VOC emissions initially released from panels to be prominent compounds released in press emissions formed on panel manufacture. Use of soy flour alone as binder produced relatively high acetaldehyde emissions from panels, whereas incorporating lignin and tannin with soy flour as adhesive binders reduced both acetaldehyde and formaldehyde emissions from panelboards post-manufacture.     

Adhesive Properties of Medium-Density Fiberboards Fabricated with Rapeseed Flour-Based Adhesive Resins

This study examined the adhesive properties of adhesives formulated with rapeseed flour (RSF), a by-product of edible oil and bio-diesel manufacture, for medium-density fiberboards (MDFs). The RSF was hydrolyzed by sulfuric acid (AC-RSFH) and sodium hydroxide (AK-RSFH) solutions of 3%, 5%, and 7%. Phenol–formaldehyde (PF) prepolymers were prepared with formaldehyde to phenol molar ratios of 1.5, 1.8, and 2.1 (1.5-, 1.8-, and 2.1-PF). RSF-based adhesives were formulated by cross-linking 35% AC-RSFH, 35% AK-RSFH, and 30% PF prepolymers on a solid weight basis. The mechanical strength and dimensional stability of the MDFs were improved by decreasing the concentration of RSF-hydrolytic agents. The properties of the MDFs bonded with RSFH/1.8-PF resins were superior to those of RSFH/1.5- or 2.1-PF resins. These results suggest that RSF can be used as a raw material for environment-friendly adhesives used in MDF production.     

高固体分酚醛环氧涂料的研究和设计

以液体酚醛环氧树脂为主基料树脂,脂肪酸改性环氧树脂为辅助基料树脂;以改性芳香胺、改性脂环胺、腰果壳油改性酚醛胺为固化剂制备了高固体分酚醛环氧涂料,该产品能够适用于更苛刻的腐蚀环境。还研究了不同固化剂及当量比对涂层物理化学性能的影响,并展望了该产品的应用前景。