纤维素/NMMO·H_2O溶液体系流变性能的研究

利用 Brookfield DV-Ⅱ型粘度计对纤维素/NMMO·H2O 溶液体系的流变性能进行了研究,讨论了温度、纤维素浓度、浆粕聚合度及添加剂等对溶液粘度的影响。结果表明,纤维素/NMMO·H2O 溶液的流动活化能较低,因此其表观粘度随温度的变化不大;纤维素浓度和浆粕聚合度的增加都可使溶液粘度增大,但纤维素浓度对溶液粘度的影响更显著;抗氧化剂没食子酸丙酯(GPE)的加入减缓了加热时溶液粘度的下降,降低了纤维素的氧化降解;二甲亚砜(DMSO)的加入可有效地控制溶液粘度,改善溶液的加工性能。     

Structure and properties of regenerated cellulose films coated with polyurethane–nitrolignin graft‐IPNs coating

A regenerated cellulose film (RC) was coated with a graft‐IPNs coating, which was composed of castor oil‐based polyurethane and 2.8 wt % nitrolignin (NL), to obtain water‐resistant films. The effects of NCO/OH molar ratio and different polyols, such as 1,4‐butanediol (BDO) and trimethanol propane (TMP), on the structure and properties of the coated RC films were investigated. With an increase of the NCO/OH molar ratio, the tensile strength of the coated films increased, but the water resistivity and size contraction hardly changed. The coated films with TMP exhibited the higher breaking elongation at 1.5 of the NCO/OH molar ratio, while those with BDO have more excellent tensile strength, water resistivity, and dimensional stability. The coated films with the graft‐IPNs coating exhibited superior water resistivity and dimensional stability. The light transmittance of the coated films was more excellent than that of the RC film. Moreover, the results from the IR and electron probe microanalysis (EPMA) showed that the chemical bonding occurred between cellulose and coating, and the introduction of NL plays an important role in the enhancement of the interface adhesion of the coated films. Atomic force microscopy (AFM) depicted the flat and dense surface of the coated films, which restricted the water vapor penetration and the size contraction, resulting in the enhancement of water resistivity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1799–1806, 2002     

一水硫酸氢钠催化合成乙二醇单甲醚乙酸酯

以一水硫酸氢钠为催化剂,由乙二醇单甲醚和冰乙酸合成了乙二醇单甲醚乙酸酯。考察了乙二醇单甲醚和冰乙酸摩尔比及催化剂用量对酯化率的影响。适宜反应条件为:乙二醇单甲醚∶冰乙酸∶一水硫酸氢钠=1∶1.75∶0.036(摩尔比),苯作带水剂,回流分水60min,酯化率达90.0%。产品经元素分析和红外光谱表征。     

固体超强酸S_2O_8~(2-)/Fe_2O_3—CoO催化合成乙酸异戊酯

制备固体超强酸催化剂S2O82-/Fe2O3—CoO,并用于乙酸异戊酯合成反应。用该催化剂通过正交试验合成乙酸异戊酯的最佳条件为:醇酸物质的量比为1.5,催化剂用量为0.8 g(以0.2 mol乙酸为准),带水剂用量为10 mL,反应时间为2.5 h,其酯化率可达98%以上。     

乙醇生产集成工艺流程的环境与经济性评价分析(英文)

乙醇是一种非常重要的可再生燃料,在本文中,从环境影响和经济效益的角度对不同的原料玉米、纤维素和乙烯生产制乙醇的工艺过程进行了评估,并利用AspenPlus模拟软件中的严格物料和能量平衡模块对典型的生产工艺进行了设计、模拟和优化。基于模拟的结果,提出了定量的环境影响方法一绿色度理论,并通过综合对比文献中报道的数据和模拟数据表明,纤维素制乙醇具有更强的环境影响优势,但在经济效益方面仍需要进一步改进。     

羧甲基纤维素阳离子化衍生物的研究现状

羧甲基纤维素阳离子化改性是制备性能优良的天然两性高分子的重要方法之一。文章综述了迄今为止羧甲基纤维素阳离子化改性所用的阳离子单体的主要类型及其接枝的若干主要途径,其中包括自由基型接枝共聚、高分子侧基反应、聚合后功能化等三大类。     

无机物——聚醋酸乙烯复合乳液粒子结构及主要性能

本文对均聚醋酸乙烯乳液及其与无机物的混合物,无机物——聚醋酸乙烯复合乳液的粒子结构进行了比较,阐述了复合乳液的主要性能。     

Catalytic hydrogenation of nitrile rubber using palladium and ruthenium complexes

The catalytic hydrogenation of acrylonitrile‐butadiene copolymer (nitrile rubber, NBR) using Pd(OAc)₂ or RuCl₂(PPh₃)₃ catalysts has been investigated in order to produce a totally saturated nitrile rubber. The hydrogenation of NBR is effective with both catalysts and achieved total conversion under the appropriate reaction conditions. In the case of palladium the effects of reaction parameters such as reaction temperature, pressure, time, catalyst concentration, and NBR concentration have been investigated. Even though both ruthenium‐ and palladium‐based catalysts are effective in the production of HNBR, the former requires harsh reaction conditions and has the drawback of gel formation under high conversion, motivating the migration to RuCl₂ (PPh₃)₃ as an alternative catalyst. The degree of hydrogenation was determined by IR and NMR spectroscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

采用变压精馏回收共沸剂的正丙醇-水共沸精馏模拟研究

本文研究了一种分离正丙醇-水的新型共沸精馏工艺,通过变压精馏的方法对夹带剂乙酸乙酯进行回收。本研究采用Aspen—Plus软件中的RADFRAC精馏模块,以NRTL活度系数方程和Hayden-O'connell逸度方程为热力学模型对本工艺流程进行模拟,讨论了塔板数、进料位置、进料量、回流比和进料温度等参数对产物精馏和共沸剂回收的分离效果的影响,优化得出最佳工艺参数。结果表明,当精馏塔的塔板数为40块,进料位置为34板,回流比为8,夹带剂与进料比为0.9:常压回收塔的塔板数为20块,进料位置为4板,回流比为0.1,减压回收塔和常压回收塔的压力分别设定为0.2 aim和1 atm时,产物正丙醇的纯度为99.22 mol%,回收的共沸剂纯度达到99.87 mo1%,本文对正丙醇的工业生产具有一定指导意义。     

Thermal decomposition behavior of γ‐irradiated poly(vinyl acetate)/poly(methyl methacrylate) miscible blends

Miscible polymer blends based on various ratios of poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) were prepared in film form by the solution casting technique using benzene as a common solvent. The thermal decomposition behavior of these blends and their individual homopolymers before and after γ‐irradiation at various doses (50–250 kGy) was investigated. The thermogravimetric analysis technique was utilized to determine the temperatures at which the maximum value of the rate of reaction (T_max) occurs and the kinetic parameters of the thermal decomposition. The rate of reaction curves of the individual homopolymers or their blends before or after γ‐ irradiation displayed similar trends in which the T_max corresponding to all polymers was found to exist in the same position but with different values. These findings and the visual observations of the blend solutions and the transparency of the films gave support to the complete miscibility of these blends. Three transitions were observed along the reaction rate versus temperature curves; the first was around 100–200°C with no defined T_max, which may arise from the evaporation of the solvent. The second T_max was in the 340–380°C range, which depended on the polymer blend and the γ‐irradiation condition. A third transition was seen in the rate of reaction curves only for pure PVAc and its blends with PMMA with ratios up to 50%, regardless of γ‐ irradiation. We concluded that γ‐irradiation improved the thermal stability of PVAc/PMMA blends, even though the PMMA polymer was degradable by γ irradiation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1773–1780, 2006