硫酸钠对纤维素醚改性水泥浆粘度的影响

纤维素醚在应用过程中有时会出现粘性明显降低.本文研究了硫酸钠对纤维素醚溶液和纤维素醚改性水泥浆的粘度的影响.结果表明,超过一定掺量的硫酸钠可以使纤维素醚溶液和纤维素醚改性水泥浆中的纤维素醚发生盐析,使纤维素醚失去对水泥浆的增粘作用;不同种类的纤维素醚,发生盐析时的最低硫酸钠掺量不同;纤维素醚发生盐析取决于硫酸钠的在水溶液中的浓度,受纤维素醚浓度和水泥掺量的影响很小.     

纤维素醚的性能及其在日用化学工业中的应用

介绍了纤维素醚的种类、制备方法、性能特点及其在日用化学工业中的应用。并提出了一些具有发展前途的纤维素醚类新品种及其潜在的应用前景。     

纤维素醚改性砂浆的研究进展

本文分析了纤维素醚的种类及其在干混砂浆的主要作用和保水性、粘度、粘结强度等性能评价方法,阐述了纤维素醚在干混砂浆中的缓凝机理、微观结构及某些特定薄层纤维素醚改性砂浆的结构形成与水化过程的关系,在此基础上,提出必须加快研究在快速失水条件下,薄层结构中纤维素醚改性砂浆的分层水化机理及聚合物在砂浆层的空间分布规律,未来在实际应用中应充分考虑纤维素醚改性砂浆受温度变化的影响、与其它外加剂的相容性等,本研究工作将促进CE改性砂浆如外墙抹灰砂浆、腻子、勾缝砂浆等薄层砂浆的应用技术发展.     

纤维素醚化改性制备热致可逆凝胶及其在稠油油藏的应用

纤维素醚因其原料来源广泛、分子结构独特、所形成的水凝胶具有热力学可逆性及良好的抗盐性能而在油田化学剂的研究开发中受到重视。介绍了纤维素醚的结构、性质及其合成方法;综述了纤维素醚的成胶机理及调节剂、添加剂对凝胶性质的影响以及纤维素醚作为热致可逆凝胶在稠油油藏封窜中的应用研究进展。     

取代均匀程度对羟乙基系列纤维素醚性能的影响

详细阐述了羟乙基系纤维素醚的取代均匀程度对纤维素醚自身(包括生物稳定性和稳泡性)和在乳胶漆中的应用(包括展色性荧光增白剂相容性)的影响,并介绍新一代甲基乙基羟乙基纤维素醚由于取代均匀而带来优越的性能表现。研究证明羟乙基系列纤维素中取代均匀程度的重要性并可帮助认识和选择合适的纤维素醚增稠剂。     

纤维素醚及其应用

本文主要叙述了纤维素醚类的世界生产能力、消费能力、主要消费去向、和它们在社会经济发展中的主要用途;同时还叙述了离子型纤维素醚和非离子型纤维素醚的主要生产国家,以及主要产品的牌号、规格、新产品研究开发动向。文中还结合国内纤维素醚现状就如何进一步开发提出了建议。     

《纤维素醚工业》编委会

《纤维素醚工业》是全国纤维素醚工业协会(筹)创办的专业性刊物，重点报道国内外纤维素醚工业科研、生产的发展动向，以及新品种、新技术、新工艺、新设备和新用途，同时适当报道国内外动态及有关消息。本刊设有“工业与技术开发”、“科学实验”、“专论和综述”、“产品应用”、     

纤维素醚分子参数对水泥浆力学性能的影响

本文比较了纤维素醚分子参数和掺量对水泥浆力学性能的影响,结果表明,纤维素醚会增加水泥浆的孔隙率,降低水泥浆的抗压强度和抗折强度,且抗压强度的降低幅度要大于抗折强度;纤维素醚的粘度或分子量越高,或者表面活性越大,其改性水泥浆的强度越低;羟乙基纤维素醚(HEC)改性水泥浆的强度比含甲基的纤维素醚改性水泥浆的强度高;随着纤维素醚掺量增加,水泥浆的抗压强度逐渐降低并趋于稳定,抗折强度则经历增加、降低、稳定和微增加的过程.     

纤维素醚改性硫铝酸盐水泥浆体中可蒸发水的1H低场核磁弛豫特征

采用低场核磁共振仪测定了不同种类及掺量的纤维素醚改性硫铝酸盐水泥浆体在各龄期的横向弛豫时间,并结合维卡仪测定水泥浆体的凝结时间,研究了纤维素醚对硫铝酸盐水泥早期水化的影响机制。结果表明:纤维素醚在水泥浆体中的吸水作用会影响浆体的早期水化。纤维素醚的掺入使得低场核磁共振的横向弛豫时间信号出现了一个代表纤维素醚吸附水的弛豫峰,峰的面积大小与纤维素醚对硫铝酸盐水泥早期水化的影响程度有关。纤维素醚的取代度越大,峰面积越大,吸水和缓凝作用相对越强。     

纤维素醚的现状与展望

介绍了纤维素醚的主要品种，分析了国内外纤维素醚的生产、需求、技术现状和前景。     

天然纤维素基医药辅料的研究及应用

结合近年来国内外研究现状,综述了天然纤维的化学结构、性能及在医药辅料领域的应用方向。     

取代基及分子量对非离子型纤维素醚表面特性的影响

根据Washburn的浸渍理论(Penetration Theory)和van Oss-Good- Chaudhury的组合理论(Combining Theory)及应用柱状灯芯技术(Column Wicking Technique),对几种非离子型纤维素醚,如甲基纤维素、羟丙基纤维素和羟丙基甲基纤维素的表面特性进行了测试。由于这些纤维素醚的取代基、取代度和分子量不同,所以它们的表面能及其组成部分有着明显的差异。数据说明,非离子型纤维素醚Lewis碱大于Lewis酸,表面自由能的主要成分是Lifshitz-van der Waals力。羟丙基的表面能及其成分都大于羟甲基。而在相同取代基和取代度的前提下,羟丙基纤维素的表面自由能正比于分子量;而羟丙基甲基纤维素的表面自由能则正比于取代度,反比于分子量。实验还发现非离子型纤维素醚中的取代基羟丙基和羟丙基甲基的表面能似乎都大于纤维素的表面能,而实验证明所测试得出的纤维素的表面能及其成分的数据是与文献所吻合的。     

非离子纤维素醚在新拌水泥基材料中的作用及研究进展

本文综合国内外相关文献,论述了非离子纤维素醚对新拌水泥基材料的改性作用,分析了最新研究进展和存在的问题。非离子纤维素醚对新拌水泥基材料具有增稠、保水、引气和缓凝作用,目前研究中存在的主要问题是没有研究纤维素醚的分子结构对新拌水泥基材料性能的影响及其机理。     

Derivatization of cellulose in lithium chloride and N-N-dimethylacetamide solutions

The derivatization of cellulose in mixtures of lithium chloride and N,N-dimethylacetamide (LiCl/DMAc) is described. A wide range of cellulose derivatives, including cellulose esters, carbamates, sulphonates and ethers, have been synthesized in homogeneous solution using the LiCl/DMAc solvent. In most cases, a high degree of substitution was achieved, and the degree of substitution could be controlled accurately. Compared to current heterogeneous synthesis of cellulose derivatives, reactions conducted in homogeneous solutions of LiCl/DMAc have many advantages: (1) reactions may be conducted at moderate temperatures; (2) less reagent is required; (3) less degradation of the cellulose occurs; and (4) substitution is uniformly controllable.     

Thermal decomposition of cellulose ethers

The thermostability and thermal decomposition kinetics of methyl cellulose (MC), ethyl cellulose (EC), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), and hydroxypropyl–methyl cellulose (HPMC) were characterized in nitrogen and air by thermogravimetry (TG). Various methods of kinetic analysis were compared in case of thermal degradation of the five cellulose ethers. The initial decomposition temperature (T_d), temperature at the maximum decomposition rate (T_dm), activation energy (E), decomposition reaction order (n), and pre-exponential factor (Z) of the five cellulose ethers were evaluated from common TG curves and high-resolution TG curves obtained experimentally. The decomposition reactions in nitrogen were found to be of first order for MC, EC, and HPMC with the average E and ln Z values of 135 kJ/mol and 25 min⁻¹, although there were slight differences depending on the analytical methods used. The thermostability of cellulose ethers in air is substantially lower than in nitrogen, and the decomposition mechanism is more complex. The respective average E, n, ln Z values for HEC in nitrogen/air were found to be 105/50 kJ/mol, 2.7/0.5, and 22/8.3 min⁻¹, from constant heating rate TG method. The respective average E, n, and ln Z values for three cellulose ethers (EC/MC/HPMC) in air are 123/144/147 kJ/mol, 2.0/1.8/2.2, 24/28/28 min⁻¹ by using high-resolution TG technique. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2927–2936, 1999     

Evaluation of Structural Properties of Cellulose Ether-Corn Starch Based Biodegradable Films

The object of this study was to investigate the physicochemical interactions between starch and cellulose ethers when they were blended to obtain biodegradable films. Fourier transform infrared spectroscopy results revealed the hydrogen bond formation between polymer chains and/or plasticizer molecules and hence good compatibility of the film constituents. X-ray diffraction (XRD) patterns indicated that cellulose ethers could be used to increase the strength and stiffness of the starch films due to their improvement on crystallinity. Simultaneous evaluation of XRD and optical microscopy results revealed that methylcellulose films had three-dimensional ordered crystalline structure and starch and carboxymethylcellulose films showed randomly distributed small crystallites and amorphous regions.     

纤维素混合醚酯的开发与应用

含有(羟)烷氧基、酯基的纤维素醚酯是一类重要的天然高分子衍生材料,可广泛应用为肠溶包衣材料、感光材料、传感材料等,文章以醋酸羟丙基甲基琥珀酸酯和醋酸羟丙基甲基酞酸酯为主线,介绍二者的结构、制备方法、理化性质、性能和应用现状。     

Preparation of cellulose derivatives containing carbazole chromophore

Cellulose derivatives containing long hydrocarbon side chains and the carbazole chromophore are prepared. N‐4′‐Bromobutylcarbazole is first synthesized from carbazole and 1,4‐dibromobutane. Alkylated carbazole is then reacted with cellulose acetate in dimethyl sulfoxide solution to produce cellulose ethers containing the desired chromophore. Polymers containing a mixture of alkyl side chains are also prepared by the subsequent addition of 1‐bromododecane to the reaction mixture. Characterization of the resulting cellulose derivatives by FTIR spectroscopy indicates that the deacetylation of cellulose acetate and the subsequent etherification are both complete. In addition, the incorporation of the carbazole chromophore is clearly shown by ¹H‐ and ¹³C‐NMR spectroscopy. Polymers of different carbazole content, ranging from 2.9 to 1.1 chromophores per anhydroglucose repeat unit, are obtained by varying the reaction conditions. Substitution is found to be controlled primarily by the quantity of alkylating agent introduced while variation of the reaction time has little effect. This method is used to prepare (dodecyl)_y(N‐4′‐carbazolylbutyl)_xcellulose, (decyl)_y(N‐4′‐carbazolylbutyl)_xcellulose, and (butyl)_y(N‐4′‐carbazolylbutyl)_xcellulose. Cellulose acetate can be replaced by (methyl)cellulose as the starting material to obtain analogous products. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2764–2772, 1999     

RING-SIZE AND SUBSTTTUENT EFFECTS IN THE SOLVENT EXTRACTION OF ALKALI METAL NITRATES BY CROWN ETHERS IN 1,2-DICHLOROETHANE AND 1 -OCTANOL

ABSTRACT

The extraction of alkali metal nitrate salts by solutions of crown ethers in each of the two diluents 1,2-dichlorethane and 1-octanol has been surveyed. The crown ethers include 18-crown-6, 21-crown-7, and 24-crown-8 ethers bearing cyclohexano, benzo, t-alkylbenzo, and/or furano substitutents. The extraction efficiencies of the different crown ethers are examined in terms of ring-size, substituent, and solvent effects. Partition ratios for the crown ethers between water and either 1,2-dichloroethane or 1-octanol are discussed. The extraction selectivities, expressed as the separation factor for cesium over sodium, are examined in relation to crown ether structure.     

聚甲醛二烷基醚的研究进展

高十六烷值柴油调和组分———聚甲醛二烷基醚是目前世界上公认的环保型燃油组分,本文从我国经济、社会发展方面简要介绍了发展煤基液体燃料的必要性,并对甲醇基含氧组分聚甲醛二烷基醚的国内外研究进展进行了较为详细的介绍,包括国内外合成聚甲醛二烷基醚的方法,同时介绍了聚甲醛二甲基醚的部分理化性质及热力学函数值,指出研究甲醇基车用柴油替代燃料聚甲醛二烷基醚的必要性。