木质素在超临界甲醇和乙醇溶剂中液化过程分析

通过研究木质素分别在超临界甲醇和乙醇溶剂中的液化过程，分析反应温度（260～340℃）及反应时间（0～120min）对木质素在两种溶剂中的转化率、生物油收率及其组分差异的影响。实验表明，木质素在超临界乙醇中的转化率及产物收率均高于甲醇。当反应温度340℃，反应时间60min，木质素在超临界乙醇中的转化率和生物油收率比在甲醇中分别提高了16.23%和11.54%，残渣收率降低了16.23%。通过GC-MS和FTIR对生物油和残渣分析，发现生物油组分中芳香族化合物相对含量较高，在甲醇和乙醇溶剂中分别达到66.13%和58.84%；随着反应时间的延长，甲醇溶剂中残渣的醚键官能团逐渐增强，而在乙醇溶剂中则先增强后减弱。分析认为在木质素降解过程中，超临界乙醇和甲醇均可产生氢自由基作为供氢体，攻击木质素及其大分子片段中的官能团，同时使液化产物中的活性片段减活，减弱重聚合反应，从而更利于芳烃产物的生成。而甲醇在液化过程中容易与木质素断键产生的苯酚中间体发生脱氢缩合反应，通过醚键聚合产生长链芳香族化合物，形成残渣，降低生物油收率。     

Mechanism of smoke suppression by melamine in rigid polyurethane foam

The smoke suppression of rigid polyurethane foam (RPUF) modified by melamine was investigated based on three sections: the condensed phase, the carbon layer, and the gas phase. In the condensed phase, the results of thermogravimetry, X‐ray photoelectron spectroscopy (XPS) N1S spectrum, and Fourier transform infrared spectroscopy indicated that melamine could suppress the degradation of RPUF by reacting with the aromatic hydrocarbons. It also reduced the smoke generation because the volatilizable aromatic hydrocarbons were the principal smoke precursors in a fire. In the carbon layer, the decrease from 38.50% to 24.76% of the inner layer oxygen content identified by XPS full‐spectrum and C1S spectrum indicated that melamine could prevent oxygen from transferring into the inner foam by the formation of an enhanced surface carbon layer, and the enhanced carbon layer could also block the release of smoke precursors. In the gas phase, the content of total aromatic hydrocarbons declined to 59.12% according to pyrolysis gaseous chromatography mass spectroscopy and indicated that melamine could reduce the smoke precursors. The results of smoke density chamber and cone calorimeter tests revealed that the addition of the melamine could decrease the smoke density of burning RPUF. Copyright © 2014 John Wiley & Sons, Ltd.     

聚苯硫醚/热致性液晶聚芳酯的流变性及其纤维的性能研究

将自制热致性液晶聚芳酯(PEE)与聚苯硫醚(PPS)共混,通过熔融纺丝制备了PPS/PEE纤维。采用高压毛细管流变仪研究了PPS/PEE共混物的流变行为,利用扫描电子显微镜观察了PPS/PEE纤维的形态结构,通过差示扫描量热仪、热重分析仪、X射线衍射仪等表征了PEE的含量对PPS/PEE纤维热性能及结晶行为的影响。结果表明:PEE的加入大幅度降低了PPS树脂的表观黏度,减小了其对剪切速率的敏感性,提高了PPS基体的结晶速率,加快了其结晶过程,在一定程度上提高了PPS纤维的热稳定性;PEE在共混纤维中起到异相成核剂的作用,对PPS的晶型没有影响;PEE与PPS相容性较差,PEE以大尺寸微纤的形式分布于基体中。     

液化石油气芳构化技术综述

综述了国内外液化石油气芳构化技术,分析了各种液化石油气芳构化技术的特点,并指出,液化石油气芳构化技术在关注催化剂活性和稳定性的同时,还应关注催化剂选择性和副产物综合利用。     

移动床混合C4制芳烃工艺研究

移动床液化气芳构化工艺是以液化气中C4组分为原料,在固定床芳构化工艺的基础上开发出的一种新工艺,与固定床相比可降低能耗,提高产品质量。在移动床反应器上考察了反应温度和进料空速对液化气C4组分制芳烃反应的影响,结果表明:生产混合芳烃(BTX)时,最佳反应条件:温度:480～500℃,进料空速:0.5～1.0 h-1。     

精油和芳香萃取物中残留苯含量的测定

建立了测定精油和芳香萃取物中残留苯含量的方法,分别考察了静态顶空和直接进样两种进样方式、两种不同固定相的色谱柱、氢火焰离子化检测器(FID)和质谱检测器(MSD)两种检测器。实验得出结论:对于挥发性较大的样品采取直接进样的方式进行测定,不易挥发的样品采用顶空进样方式。实验结果表明,在1×10-6～2.5×10-5浓度范围内,采用不同的组合,残留苯含量均具有良好的线性关系。     

芳香族硝基化合物合成的最新研究进展

综述了近年来芳香族硝基化合物合成的研究进展,主要包括芳香硼酸、芳香卤化物及拟卤化物、芳香羧酸及芳烃碳-氢键的硝化反应、芳香胺及叠氮化合物的氧化及其反应机理的探讨。     

Synthesis of highly soluble and transparent polyimides

A novel aromatic diamine, 3,3′‐diisopropyl‐4,4′‐diaminophenyl‐4″‐methyltoluene with a 4‐methylphenyl pendant group and isopropyl side groups, was designed and synthesized in this study. Then it was polymerized with various aromatic dianhydrides including pyromellitic dianhydride, 3,3′,4,4′‐biphenyltetracarboxylic dianhydride, 4,4′‐oxydiphthalic anhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride via a one‐pot high temperature polycondensation procedure to produce a series of aromatic polyimides. These polyimides exhibited excellent solubility even in common organic solvents, such as chloroform and tetrahydrofuran. The flexible and tough films can be conveniently obtained by solution casting. The films were nearly colorless and exhibited high optical transparency, with the UV cutoff wavelength in the range 302–365 nm and the wavelength of 80% transparency in the range 385–461 nm. Moreover, they showed low dielectric constants (2.73–3.23 at 1 MHz) and low moisture absorption (0.13%–0.46%). Furthermore, they also possessed good thermal and thermo‐oxidative stability with 10% weight loss temperatures (T_10%) in the range 489–507 °C in a nitrogen atmosphere. The glass transition temperatures of all polyimides are in the range 262–308 °C. Copyright © 2012 Society of Chemical Industry     

HER扩链剂的合成及其在聚氨酯弹性体中的应用

详细介绍了一种常用的芳香族二醇扩链剂——间苯二酚双（2-羟乙基）醚（HER）的性能特点及3种主要合成方法,概述了HER在浇注型聚氨酯弹性体、热塑性聚氨酯弹性体、高尔夫球材、聚氨酯轮胎、熔纺氨纶、聚氨酯热熔胶等领域的应用情况。     

Studies on Bi-Cyclic Aromatics Extraction using Furfural and N-Methyl Pyrrolidone (NMP) as Solvent

In this work, the separation of naphthalene, a bicyclic aromatic component, by the solvent extraction method from a model oil (p-xylene, iso-octane, and naphthalene) using furfural and n-methyl pyrrolidone (NMP) as solvent has been investigated. A four factor Box-Behnken design was used to study the individual and interactive effects of four main parameters namely paraffinic content in model oil (P/F): 0.7–0.8; solvent to feed ratio (S/F): 0.5–1.0; temperature (T): 20–40°C; time (t): 1–3 h for furfural and 1–7 h for NMP on the yield and selectivity of naphthalene. Gas chromatography was carried out to analyze the composition of raffinate and extract phases. Various polynomial models were fitted to find out the best model for the system. Pareto analysis of variance (ANOVA) and other statistical tests were performed to check the significance of the model. Furfural was found to be a better solvent as compared to NMP, both in terms of yield and selectivity. The operating conditions leading to maximum aromatic recovery have been optimized. The optimum conditions for furfural was found to be P/F = 0.7, S/F = 0.5, temperature = 24°C and time = 3 h whereas the optimum conditions for NMP were: P/F = 0.76, S/F = 0.76, temperature = 22°C, and time = 4.1 h.