Synthesis of Poly-(p-Phenylenebenzobisthiazole) Used for Manufacture of Thermostable High-Modulus Fibres

The possibility of reducing the duration of synthesis of poly(p-phenylenebenzobisthiazole) (PPBT) from 2,5-diamino-1,4-dimercaprobenzene and terephthalic acid in polyphosphoric acid medium with production of a high-molecular-weight with [] = 24-29 dl/g is demonstrated. It is shown that with a lower duration of synthesis of PPBT, polycondensation solutions have a lower viscosity (1500-2000 Pa·sec) at 150-165°C, which facilitates spinning of high-strength and high-modulus fibres.     

基于Excel逐板计算法求解连续精馏操作型问题

我们以分离苯-甲苯体系为例,借助于Excel计算功能,通过其＂规划求解＂工具、＂IF条件判断＂和＂MATCH＂函数的联合使用,实现了连续精馏操作型问题的自动试差计算。该法可与目前教学中的图解法相结合,解决因试差法计算过程冗长、乏味,课堂学时有限,老师无法翔实讲授其具体计算过程,学生无兴趣,不愿花时间进行练习的难题。另外,我们还对变工况过程进行快捷准确工程分析,调整相关参数,提出合理的应对措施,增强学生分析问题、解决问题的能力。     

Variable Temperature IR Spectroscopy in the Studies of Oxide Catalysts

The paper deals with the development of cell technique for spectral measurements and new possibilities provided by the studies at variable temperatures for obtaining information about the nature and properties of active sites. Difficulties caused by light scattering on the pressed samples of catalysts are discussed. Spectroscopy at low temperatures enables us to broaden the number of probe molecules for acidic or basic sites and to obtain data on the active site concentrations from the band intensities. The necessary values of absorption coefficients can be specified from their correlation with the frequencies of adsorbed molecules. At high surface coverages the measurements are complicated by lateral interactions between the adsorbed molecules. The application of isotopic dilution enables one to distinguish between static interaction, which modifies the catalytic and adsorption properties of surfaces, and dipole coupling. The latter shifts the bands of probe molecules, distorting the surface acidity data. Co-adsorption of acidic and basic molecules leads to the mutual enhancement of adsorption. This is revealed in the phenomena of induced Brønsted acidity and induced basicity or Lewis superacidity. Another important property of surface sites detectable by variable temperature spectroscopy is linkage isomerism of surface species when molecules form with surface sites complexes of unusual structure. Such complexes, e.g. the energetically less favourable O-bonded isomer of CO, could be considered as activated states or intermediates in catalytic reactions. Analysis of the band intensity dependence on temperature and pressure provides valuable information about the thermodynamics of adsorption.     

Tricky IR Monomer Spectroscopy in Planar Molecular Jets

An experimental technique based on double resonance spectroscopy in the collisional environment of a seeded molecular jet expansion is described. Using this technique, hot band spectra of several small hydrocarbons have been investigated as well as the (related) collision-induced relaxational behavior upon vibrational excitation. The collisional relaxation in the jet is of crucial importance to the experiments presented here as it distributes the population over many rovibrational states after initial excitation by a pump laser. A second IR laser then probes the transitions starting from the vibrationally excited state(s), as hot bands. In that way one enters an energy region around 4000 cm⁻¹, beyond the highest fundamental bands. The possibility to label an individual rovibrational state with the pump laser enables us to obtain reliable initial spectroscopic assignments. In addition, the present technique allows one to distinguish the cold bands due to depletion of the vibrational ground state, which may reveal new and surprising spectral features as well.     

IR Spectroscopy in Rank and Group Assignment of Coal

The possibility of express determination of the characteristics V _IR ^daf , R_{o, IR}, y_IR, ΣLC_IR, and A _IR ^d used in the ranking of coal on the basis of IR spectroscopy is assessed for a specific example: Kuznetsk coals of different maceral composition and metamorphic development. The IR characteristics are compared with values obtained by standard methods (V^daf, R_{o, r, y}, ΣLC, and A^d).     

In-situ IR Monitoring the Synthesis of Amphiphilic Copolymery P(HEMA-co-tBMA) via ARGET ATRP

The amphiphilic copolymer poly(hydroxyethyl methacrylate-co-tert-butyl methacrylate) [P(HEMA-co-tBMA)] was synthesized by activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP), with the synthesis process monitored by in-situ infrared spectroscopy (IR). The molecular weight, chemical structure and characteristics of the copolymer were determined by 1H NMR, gas chromatography and gel permeation chromatography. The influences of various parameters on the living polymerization were explored. The molecularweight of the copolymer with narrowmolecularweight distribution (M_w/M_n b 1.50) increases approximately linearly with the monomer conversion, indicating a good control of polymerization. In the reaction temperature range from 50℃ to 90℃, the monomer conversion is higher at 60℃. The tBMA conversion rate decreases gradually with the increase of tBMA content, while the HEMA conversion is hardly affected by HEMA content. Weak polar solvent is more favorable to the polymerization compared to polar solvent. The molar ratio of reducing agent to catalyst has significant effect on the polymerization and increasing the amount of reducing agent will accelerate the reaction rate but causes wider molecular weight distribution. It is indicated that in-situ IR monitoring contributes to a more in-depth understanding of the mechanism of methacrylate monomer copolymerization.     

Nanophotothermolysis of Poly-(vinyl) Alcohol Capped Silver Particles

Laser-induced thermal fusion and fragmentation of poly-(vinyl) alcohol (PVA)-capped silver nanoparticles in aqueous medium have been reported. PVA-capped silver nanoparticles with an average size of 15 nm were prepared by chemical reduction technique. The laser-induced photo-fragmentation of these particles has been monitored by UV-visible spectroscopy and transmission electron microscopy. The morphological changes induced by thermal and photochemical effects were found to influence the optical properties of these nanoparticles.     

Curing of Poly-(1,4-Phenylene Sulphide) in the Presence of its Oligomers

Abstract

The curing of poly-(1,4-phenylene sulphide) with its HS-terminated oligomers has been studied. The influence of crosslinking on crystallinity of poly-(l,4-phenylene sulphide) has been examined. The mechanism of curing has been discussed.     

Water Sorption and Diffusion in Poly-(3-Hydroxybutyrate) Films

For improved understnding of the transport of low-molecular substances' in moderately hydrophobic polymers, the temperature dependence of water vapor sorption and diffusion in poly-(3-hydroxybutyrate) (PHB) was studied for the first time. Equilibrium sorption and diffusion kinetics were determined by a quartz McBain's vacuum microbalance technique in the temperature range 303-333 K. The water molecule interaction with the polymer matrix was analyzed for wet PHB films by the Fourier transform infrared spectroscopy technique. Water sorption isoterms are interpreted as a superposition of free water sorption estimated by the Flory-Huggins equation and water immobilized on car-bony 1 groups of PHB. The immobilization effect was described by a Lmgmuir-type equation. The dependence of diffusivity on water concentration was described in the framework of Fujita's immobilization model in which the growing function D _w versus C _w characterized the filling degree of carbonyl groups as sites of immobilization in the polymer. Enthalpy of free water sorption (12 kJ/mol) and water immobilization (42 kJ/mol) as well as the activation energy of water diffusion coefficients (71 kJ/mol) in noncrystalline areas of PHB were determined.     

Monitoring of the Synthesis of Hyperbranched Poly(urea‐urethane)s by Real‐Time Attenuated Total Reflection (ATR)‐FT‐IR Spectroscopy

Summary: The reaction of 2,4‐TDI and DEA, as an A₂ + B^*B₂ polymerization system towards hyperbranched HPUs was followed using in situ ATR‐FT‐IR spectroscopy. The decrease in intensity of the NCO absorption band of the reactive isocyanate group of 2,4‐TDI along with the formation and growth of the new characteristic bands of urethane and urea groups were detected. The reactivity difference of both NH and OH groups towards the NCO group at low temperatures was proven. The rate of the reaction was found to be affected by changing the temperature, the rate of addition of the B^*B₂ monomer and the type of solvent. Moreover, the increase of the carbonyl vibration and the amide II bands of urea was very obvious during the addition of the stopper DEA. Thus, it was possible to verify the individual reaction steps of this complex polyreaction and to correlate these with the structural development of the resulting macromolecules.

Characteristic vibration bands of urethane and urea groups in the IR spectra (1 780–1 480 cm^?1) during the polymerization reaction.     

Curing Behaviour of Poly-(1,4-phenylene sulphide) with Quinones

Abstract

The curing reaction of poly-(1,4-phenylene sulphide) (pps) with tetrachlorobenzoquinone (chloranile), quinhydrone and antraquinone are studied by X-ray diffraction differential scanning calorimetry, Fourier-transform infrared spectroscopy and thermo-gravimetric analysis. The results are discussed in terms of a mechanism for curing.     

Characteristics of Jet Flow of Poly-(p-Phenylene Terephthalamide) Solutions

Jet flow of a 19% liquid-crystalline solution of poly-(p-phenylene terephthalamide) is modeled with a viscoelastic medium with the same relaxation time and viscous flow obeying a power law. Equations are reported for calculating the jet flow rate profile in the case of a power or logarithmic dependence of the modulus of hyperelasticity on the tensile stress. It is shown that the change in the viscosity along the length of the jet is extremal in character with a high jet draw ratio. A hypothesis is advanced concerning the dependence of stabilization of flow on the resonance in drawing of the jet with the conditions of appearance of the extremal character of the viscosity dependence along the length of the jet.     

聚天冬氨酸的合成制备研究

以马来酸酐为原料合成聚天冬氨酸,研究了合成聚天冬氨酸时铵盐的种类、马来酸酐与碳酸铵的比例、合成时间以及合成温度对目的产物聚天冬氨酸产率和分子量的影响。得出产率最高的合成工艺条件为:n(马来酸酐)∶n(碳酸氨)=1∶1.2,聚合温度为180℃,聚合时间为1.0 h。制备的聚天冬氨酸纯度高达90%以上,产率也在94%以上。所制备的聚天冬氨酸具有一定的缓蚀阻垢作用,可广泛应用于工业循环冷却水处理、油田水处理等领域。     

连续法合成邻(对)硝基苯甲醚

邻(对)硝基苯甲醚是十分重要的化工原料,用于制备多种染料、医药和食品添加剂。生产邻(对)硝基苯甲醚的传统方法都是间歇法操作,周期长、能耗高、效率低。吉林石化公司研究院开发成功了连续法合成邻(对)硝基苯甲醚的工艺技术,用静态混合器代替传统的搅拌釜作为反应器,缩短了反应时间,降低了硝基苯酚钠的含量,提高了硝基苯甲醚的选择性,使装置生产能力大幅提高,生产成本下降,同时减少了操作强度,改善了操作环境。     

Gaussian 09软件包在红外光谱教学中的应用

介绍了Gaussian软件在分析化学红外光谱教学中的具体应用,有利于学生理解红外光谱的本质,有效增强学生的学习兴趣和积极性,提高教与学的效率。     

有机蒙脱土对PET后缩聚反应的影响

实验研究了有机蒙脱土对PET后缩聚反应过程的影响。结果表明有机蒙脱土对PET缩聚反应的前期有加速作用，但由于对气液传质过程有阻碍作用，导致了PET后缩聚反应的速度下降。蒙脱土的存在还使缩聚过程中二甘醇(DEG)基团及端羧基基团浓度上升。根据缩聚反应机理建立了PET后缩聚过程的数学模型，并依据实验结果拟合出缩聚反应动力学参数及气液传质系数。模型计算结果能较好地反映PET后缩聚过程中特性粘数的变化及DEG基团的生成规律，但对端羧基浓度的变化存在较大的偏差。     

有机化合物及聚合物的计算机辅助红外光谱法鉴定

建立了计算机辅助红外光谱法鉴定有机化合物及聚合物的新方法,介绍了计算有机化合物和聚合物的一些经验公式。程序设计首先收集、整理常用聚合物、有机添加剂和有机小分子的红外光谱数据,然后提取反映该物质特征的吸收峰数据,制作ACCESS数据库,利用VisualBasicDAO数据链接方式,根据查询要求动态链接数据库,利用要求查询的聚合物特性,经过经验公式的算法翻译,生成SQL查询语句进行查询。