Kinetik der Polyphenylensulfid-Synthese

The kinetics of the polycondensation of Na₂S · 3H₂O and 1,4-dichlorobenzene to poly(phenylene sulfide) in 1-methyl-2-pyrrolidone as solvent was studied in a differential scanning calorimeter at temperatures from 220°C to 260°C. Stainless steel high-pressure capsules of 30 μl volume were used as micro reactors. The reaction is highly exothermic. At 220°C the enthalpy of reaction reaches a value of 180 kJ/mol. The polycondensation is characterized by an autocatalytic behaviour. The kinetics can be modelled by a second order equation with respect to the stoichiometrically charged monomers and a propagation rate constant being dependent on conversion. The activation energy of the polycondensation is 95 kJ/mol.     

Poly(phenylene sulfide): Polymerization kinetics and characterization

The polycondensation kinetics of aromatic nucleophilic substitution on 1,4-dichlorobenzene by sodium sulfide has been investigated at 195°C in N-methyl pyrrolidone. The reaction follows second-order kinetics. The rate is bimodal with an initial slow rate till 50% conversion followed by a faster rate between 50 and 97% conversion. The specific reaction rates have been evaluated as 3.97 × 10^?3 L m^?1 s^?1 and 1.02 × 10^?2 L m^?1 s^?1 for the initial and later part (50–97%) of the reaction. The development of the degree of polymerization with reaction time was followed by end-group analysis and intrinsic viscosity measurements of polymer samples collected at different conversions. The reaction differs from conventional polycondensation reactions in two aspects. Polymer formation occurs at low conversions, and a significant amount of uncreacted monomer is present even at very high conversions. Unlike other precipitation polymerization reactions, the polymer chain continues to grow even after precipitation.     

Na2S-SO2反应体系中H2S产生的过饱和态分析

向Na2S溶液中通入低浓度SO2气体以生成H2S，H2S从液相中逸出时，存在一突跃现象。本文根据这一现象，结合Y．T．Shah等提出的吸收－反应－解吸体系中过饱和态存在的条件，通过理论分析，得出在Na2S-SO2-H2S4反应体系中H2S解吸存在过饱和现象。     

Zur Kinetik der stabilisierten Fällungs-polymerisation eines Kationischen Monomeren in wäßrigen Natriumchlorid-Lösungen

The stabilized free-radical precipitation polymerization of the cationic monomer N-(2-methacryloyloxyethyl)-N,N-dimethylbenzylammonium chloride (MADAMBQ) in aqueous solutions of sodium chloride was studied by reaction calorimetry. Poly(ethylene oxide) was used as stabilizer. The rate of polymerization reaches its maximum immediately after initiation and remains nearly constant up to 50 % conversion followed by a decrease that could be described by a first order kinetics. The particles formed are approximately 1 to 30 μm in diameter and are stable over a period of several months. A model based on the theory of homogeneous particle nucleation is suggested to describe the kinetic course of polymerization, taking into account the rate of polymerization in both phases. With the assumption that the concentration of monomer in the phases is determined by a Nernst distribution law, the kinetics of the early stage of polymerization can be modelled reasonably well. The solution polymerization and the unstabilized precipitation polymerization of MADAMBQ was also studied.     

过碳酸钠热分解动力学研究-(Ⅰ)模型判别

采用等温法对文献中提及的两种分解动力学模型—核形成、核增长模型和自催化模型进行了判别。对于一条α-t曲线,t_1/t_2=Const时,t_1和t_2对应的分解率α_1和α_2是不同的,以α_1对α_2作图,并与理论曲线进行比较。结果表明,过碳酸钠的分解动力学模型为自催化模型。     

己二酸与1,2-丙二醇或1,4-丁二醇自催化酯化反应的动力学研究

以己二酸与1,2-丙二醇和1,4-丁二醇为例,考虑水的排出以及密度的变化对酯化反应动力学的影响,认为用物质的量浓度更为科学,推导出以物质的量浓度来表示酸浓度的总包动力学方程,计算出体系的反应速率常数和活化能,并与以质量摩尔浓度表示的酸浓度所得出的动力学参数进行了比较。     

(E)-2,3-二溴-2-丁烯-1,4-二醇的合成

在2-丁炔-1,4-二醇与溴的加成反应体系中,添加适量的溴化钠,不但可以有效地提高(E)-2,3-二溴-2-丁烯-1,4-二醇的收率,而且反应可以在室温下进行,避免了低温冷却,更有利于工业化的生产。     

异丁醛与1,4-丁烯二醇缩合反应的研究

将异丁醛与1,4-丁烯二醇缩合得到产物二氧七环,对产物进行了元素分析和IR分析.初步探讨了反应物浓度、温度、酸度和反应时间对产物产率的影响.     

湿式过氧化物氧化法处理硫化钠废碱液的动力学研究

废碱液中富含硫化物会对废液的生物降解起抑制作用,故废液在排往污水处理之前常须进行预处理。今采用常用于有机物废水处理的湿式过氧化物(Fenton试剂)催化氧化法(CWPO)来对含硫化物的废碱液进行处理,并对其催化氧化硫化钠过程的反应动力学进行研究。实验结果表明：用CWPO工艺对于硫化钠废碱液的处理具有良好的催化氧化效果,反应在120分钟内硫化钠的去除率可达到99％以上。过氧化物催化氧化硫化钠过程符合一级反应动力学,催化剂Fe^2 的浓度和溶液的pH值对其影响较小,实验验证了推导出的动力学模型能很好地反映CWPO工艺下硫化钠的降解。过氧化物湿式催化氧化硫化钠废碱液的动力学方程为：-dC/dt=26.1095exp(-29353/RT)[H2O2]0^0.979C。     

Polyurethane macroazoinitiators based on 2,2′-azobis(2-cyanopropanol) kinetic studies

2,2′-Azobis(2-cyanopropanol) (ACP) was used to react with 4,4′-methylene diphenyl diiso-cyanate (MDI) and α,ω-hydroxy polycaprolactone (PCL) in the presence of dibutyltin di-laurate (SnDBDL) as a catalyst in a two-stage polycondensation to produce a polyurethane macroazoinitiator (PUMAI). The kinetics of the reaction of ACP with a monoisocyanate (para-tolylisocyanate, p-TI) was followed using high performance liquid chromatography. The condensation reaction was performed in 2-butanone, with SnDBDL as catalyst. Kinetic models were suggested to calculate rate constants. The experimental results showed an autocatalytic effect of the reaction by urethane groups and a different reactivity of the second OH group of ACP after the reaction of the first one. The kinetics of the reaction of MDI with ACP and PCL were studied using size exclusion chromatography. Polycon-densation was performed under the same conditions used for the model system. The reaction rates of MDI with ACP and PCL were compared. ACP was shown to be slightly more reactive with MDI than PCL. The first stage of PUMAI synthesis (reaction of ACP with a large excess of MDI) was studied. Some side reactions with isocyanates occured. Finally, a typical PUMAI was synthesized. © 1996 John Wiley & Sons, Inc.     

Studies on the semirigid chain polyamide—poly(1,4-phenyleneterephthalamide)

In this article, the polycondensation of terephthaloyl chloride and p-phenylenediamine was systematically studied, including the liquid–crystalline state of the solution and the spinning of poly(1,4-phenyleneterephthalamide) (PPTA). High-molecular-weight PPTA with ε_inh = 5–7 was prepared and the main factors influencing the solution polycondensation of 1,4-phenylenediamine with terephthaloyl chloride were studied in detail. Experimental results showed that the water content of the reaction system, reactant concentration, and volume ratio of mix solvents have a great influence on the inherent viscosity of the poly(1,4-phenyleneterephthalamide) obtained. The highest ε_inh was obtained at 0.3M/liter reactant concentration in a mixed solvent ratio HMPA/DMAC of 4/1 (by volume), at 0.35M/liter reactant concentration in a mixed solvent of HMPA/NMP = 7/3, and at 0.5M/liter of reactant concentration in a mixed solvent of HMPA/THF = 9/1. The water content must be controlled to less than 100 ppm in the polymerization system. In the early stage of the polycondensation process, the ε_inh of the polymer obtained increased rapidly with time. The system gelled within 2 or 3 min, while the monomer conversion reached about 100%. However, the reaction of polycondensation continued after gelation and the ε_inh of the polymer increased appreciably. We have studied the viscosity behavior at 20–155°C for the anisotropic solution of PPTA in 100% sulfuric acid (ε_inh of PPTA 2.5–4.9). Experimental results showed that, at low concentrations the viscosity of isotropic solution increases with the increase of polymer concentration to reach a maxium near the critical polymer concentration, beyond which the solution changes to an anisotropic liquid–crystalline solution. The appropriate spinning region was obtained as shown in the phase diagram determined by viscosity, degree of depolarization anisotropy, and region of thermal depolymerization. Fibers of PPTA with high modulus and high tenacity were obtained by dry-jet wet spinning. The fibers obtained have a tenacity of ～22 g/denier, a modulus of ～600 g/denier, and elongation at break ～3.5%.     

环己烷液相无催化氧化模拟计算及动力学的修正

1 模拟计算1.1 动力学和流动模型模拟计算中采用陈纪忠等建立的动力学模型,其反应网络为:描述该6种组分的生成或消失速率的动力学方程式在文献[1]中已有详细报道。从冷模研究得到:液相流动为全混流;u_g≥7 cm/s 时气相流况可视作平推流。若从各种流动模型的计算结果看,气相即使作为全混流,计算结果差异也甚小。本文采用液相全混、气相平推的流动模型。     

New types of heat-resistant,flame-retardant ferrocene-based polyamides with improved solubility

A novel ferrocenyl diamine (FDA) was prepared by the condensation reaction of 1,1′-ferrocenedicarbonyl chloride with 2 mol of 2,6-bis(4-aminophenoxy)pyridine. A series of ferrocene-based polyamides was prepared via polycondensation reaction of FDA with various diacid chlorides in N-methyl-2-pyrrolidone (NMP) using trimethylchlorosilane (TMSCl) as activating agent. The monomer and polyamides were characterized and inherent viscosity, solubility, thermal stability and behavior, flame-retardancy, and crystallinity of the polymers were studied. The polymers showed good heat-resistant, flame-retardancy, and also improved solubility in polar aprotic solvents.     

Preparation and properties of poly(amideether-imide)s derived from 1,4-bis(4-aminophenoxy)benzene,trimellitic anhydride,and various aromatic diamines

An imide ring containing dicarboxylic acid, 1,4-bis(4-trimellitimidophenoxy)benzene (III), was prepared by the condensation of 1,4-bis(4-aminophenoxy)benzene and trimellitic anhydride. A series of new poly(amide-ether-imide)s were prepared by the direct polycondensation of diimide-diacid III with various aromatic diamines using triphenyl phosphite and pyridine as condensing agents inN-methyl-2-pyrrolidone (NMP) in the presence of calcium chloride. The highest inherent viscosity value of a poly(amide-ether-imide) obtained was 1.78 dL/g (inN,N-dimethylacetamide, DMAc, at 30 °C). Flexible films with excellent tensile properties were cast from DMAc solutions. Glass transition temperatures of these poly(amide-ether-imide)s were recorded in the range of 248–297 C. These polymers do not show obvious weight loss before 400°C; the decomposition temperatures at which 10% weight loss in nitrogen and in air were observed for these poly(amide-ether-imide)s in the range of 521–564°C and 501–539°C, respectively. The polymers derived fromp-phenylenediamine or the diamines containing 1,4-bisphenoxy units exhibited a higher degree of crystallinity and higher initial decomposition temperatures but poor solubility in organic solvents.     

对苯二甲酸-丁二醇催化单酯化反应动力学(英文)

The chemical kinetics of the monoesterification between terephthalic acid (TPA) and 1,4-butanediol (BDO) catalyzed by a metallo-organic compound was studied using the initial rate method. The experiments were carried out in the temperature range of 463-483 K, and butylhydroxyoxo-stannane (BuSnOOH) and tetrabutyl titanate [Ti(OBu)4] were used as catalyst respectively. The initial rates of the reaction catalyzed by BuSnOOH or Ti(OBu)4 were measured at a series of initial concentrations of BDO (or TPA) with the concentration of TPA (or BDO) kept constant. The reaction orders of reagents were determined by the initial rate method. The results indicate that the reaction order for TPA is related with the species of catalyst and it is 2 and 0.7 for BuSnOOH and Ti(OBu)4 respectively. However, the order for BDO is the same 0.9 for the two catalysts. Furthermore, the effects of temperature and catalyst concentration are investigated, and the activation energies and the reaction rate constants for the two catalysts were deter-mined.     

Linear polythioesters. XV. Products of interfacial polycondensation of 1,4-dimercapto-tetramethylbenzene with some aliphatic and aromatic acid dichlorides

New polythioesters by interfacial polycondensation of 1,4-dimercaptomethyl–tetramethylbenzene with oxalyl, succinyl, adipoyl, suberoyl, sebacoyl, and isomeric phthaloyl dichlorides were obtained. To define the optimal conditions for interfacial polycondensation, the influence of the following factors on yield and value of reduced viscosity were studied: type of organic phase, concentration of hydrogen chloride acceptor, the quantitative ratio of aqueous to organic phase, molar ratio of reagents rate of acid chloride addition, contribution of benzyltriethylammonium chloride as a catalyst, and the temperature of the reaction. Thorough studies were carried out only for polycondensation of the dithiol with adipoyl, sebacoyl, and isophthaloyl chlorides. The structure of polythioesters obtained under the model conditions was determined by elementary analysis and infrared spectra. Initial decomposition temperature, mass loss in percentage at the same temperature, maximum rate of decomposition, and mass loss percentage at 100–400°C were defined from the curves of thermogravimetric analysis. Chemical resistance of the polythioesters was determined by treatment with some organic solvents, mineral acids (concentrated and 10%) and sodium hydroxide (10% and 50%). The molecular weight was not measured because of the low solubility of the polythioesters.     

Hemicellulose Hydrolysis in the Presence of Heterogeneous Catalysts

A prominent autocatalytic effect in the hydrolysis of hemicelluloses was observed in the presence of heterogeneous cation-exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the non-hydrolysed sugar monomer units and the increase of the rate constant as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and the kinetic parameters, describing the autocatalytic effect, were determined by non-linear regression analysis. The kinetic model explained very well the overall kinetics, as well as the product distribution in the hydrolysis of hemicelluloses.     

头孢地嗪钠溶剂化物结晶过程自催化动力学

采用在线拉曼光谱在不同结晶温度和溶液初始浓度的条件下,研究了头孢地嗪钠溶剂化物结晶过程的动力学行为,从热力学和成核机理的角度分析了温度和初始浓度对动力学的影响。根据动力学曲线的特征,将头孢地嗪钠溶剂化物的结晶过程假定为"自催化"过程。针对头孢地嗪钠溶剂化物结晶过程的特殊性,修正了Prout-Tompkins模型;并通过不同温度下的动力学数据,采用多元线性回归拟合了头孢地嗪钠溶剂化物结晶过程的自催化动力学模型参数E和k。     

Hemicellulose Hydrolysis in the Presence of Heterogeneous Catalysts

A prominent autocatalytic effect in the hydrolysis of hemicelluloses was observed in the presence of heterogeneous cation-exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the non-hydrolysed sugar monomer units and the increase of the rate constant as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and the kinetic parameters, describing the autocatalytic effect, were determined by non-linear regression analysis. The kinetic model explained very well the overall kinetics, as well as the product distribution in the hydrolysis of hemicelluloses.

     

Linear polythioesters. XI. Products of polycondensation of some isomeric di(mercaptomethyl)dimethylbenzenes with isophthaloyl and terephthaloyl chlorides

New polythioesters have been obtained by polycondensation of 4,5-di(mercaptomethyl)-1,2-dimethylbenzene, 4,6-di(mercaptomethyl)-1,3-dimethylbenzene, and 2,5-di(mercaptomethyl)-1,4-dimethylbenzene with isophthaloyl and terephthaloyl chlorides. To define the optimal conditions of polycondensation, polythioester from 2,5-di(mercaptomethyl)-1,4-dimethylbenzene and isopthaloyl chloride was choosen as a model system. The optimalization of the polycondensation conditions was carried out by low-temperature and high-temperature solution polycondensation as well as by interfacial polycondensation. To determine the optimal conditions for polycondensation the following parameters have been studied. The kind of organic solvent, concentration of reagents, temperature and time of reaction, and, in the case of interfacial polycondensation additional, the ratio of aqueous to organic phase, kind and concentration of hydrochloride acceptor, kind and concentration of catalyst and concentration of emulsifier (Mersolan) were taken into consideration. The synthesis of all described poly-thioesters obtained by polycondensation di(mercaptomethyl)-dimethylbenzenes with isophthaloyl and terephthaloyl chlorides was carried out under the same optimal conditions, established for the reaction 2,5-di(mercaptomethyl)-1,4-dimethylbenzene with isophthaloyl chloride. The structure of polythioesters was determined from infrared, X-ray, and elementary analysis. Some physicochemical, thermal, mechanical, and electrical properties as well as molecular weight of polythioesters have been determined.