N-马来酰基-氨基丙酸丁酯微乳液的微波聚合

在微波条件下，以十二烷基硫酸钠为乳化剂，过硫酸钾为引发剂的N－马来酰基－氨基丙酸丁酯（BAM）微乳液聚合。研究了聚合时间对聚合速率和转化率的影响。并用PERKIN－ELMERFTIR－1710红外光谱仪、PE－2400有机元素分析仪、DT－40差热分析仪对聚合物进行了检测。     

Ultrasonic degradation of polymer solutions. 1. Polystyrene revisited

The results of ultrasonic irradiation of polystyrene solutions in toluene, benzene and carbon tetrachloride are described. The effect of a range of conditions such as ultrasonic intensity, solution concentration and varying solvents were investigated. The non-random nature of the degradation process was clearly demonstrated and the effect of different solvents was interpreted in terms of their thermodynamic properties.     

Non-steady-state model for kinetics of free radical polymerization, 4. Direct thermal initiation

This paper deals with the non-steady-state kinetics of direct thermal initiated polymerization. The initiation is assumed to be a bimolecular reaction of the monomer. The relationship between the radical concentration and the monomer conversion is rigorously derived. In further treatment a few very close approximations are introduced based on the fact that the number of monomer molecules reacting in the initiation step is much less than that consumed in the propagation step for a process producing high polymer, and the value of the rate constant for propagation or chain transfer is much lower than that for chain termination. Expressions for various molecular parameters, such as molecular weight distribution, number-average and weight-average degrees of polymerization, and dispersity, are given. Several numerical examples are provided.     

Studies on chain transfer reaction in butadiene polymerization initiated with n‐butyl lithium and novel promoter potassium para‐methylphenoxide

The chain transfer reaction was examined in the anionic telomerization of butadiene with n‐BuLi as the initiator, potassium para‐methylphenoxide (ROK) as the novel promoter, mixed xylene as the transfer agent as well as a solvent in the presence of diglyme as the polar modifier. Effects of ROK, diglyme, and the polymerizing temperature were studied. It was demonstrated that they all promote the chain transfer reaction. The relative constant of chain transfer to the solvent was also calculated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1215–1218, 2005     

Non-steady-state model for kinetics of free radical polymerization, 3. Direct photo-initiation

The non-steady-state kinetics of directly photo-initiated polymerization were studied theoretically. Taking account of the facts that the amount of monomer consumed in propagation is much more than that in initiation for a process producing high polymer and that the rate constant of chain termination is much larger than that of chain propagation or transfer, a few very close approximations were adopted to solve the set of kinetic differential equations of the polymerization under consideration. The inexplicit function method developed in a previous paper of this series for the derivation of the molecular weight distribution function is still valid in this work. Some numerical computation was implemented to show the tendency of free radical concentration decay and the plots of molecular size distribution.     

Non-steady-state model for kinetics of free radical polymerization, 2. Redox initiation

This work deals with the non-steady-state kinetics of free radical polymerization with redox initiation. Rigorous expressions for the radical concentration, monomer conversion, molecular size distribution function, and number-average and weight-average molecular weights, etc., were derived. The molecular parameters of the resulting polymer were evaluated in relation to the polymerization conditions.     

Atom transfer radical polymerization of lauryl methacrylate

The atom transfer radical polymerization (ATRP) of lauryl methacrylate (LMA) with an ethyl 2‐bromobutyrate/CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine initiation system was successfully carried out in toluene, and poly(lauryl methacrylate) with a low polydispersity (1.2 < weight‐average molecular weight/number‐average molecular weight < 1.5) was obtained. Plots of ln ([M])₀/([M]) versus time and plots of the molecular weight versus conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization. The rate of polymerization was 0.56‐order with respect to the concentration of the initiator and 1.30‐order with respect to the concentration of the Cu(I) catalyst. In addition, the effect of the solvent on the polymerization was investigated, and the thermodynamic data and activation parameters for the solution ATRP of LMA were reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1117–1125, 2003     

Calculation method of molecular weight averages in polymerization with chain-length-dependent termination

A systematic method for calculating the molecular weight distribution moments in free radical polymerization where termination rate depends on the size of the participating radicals, is presented. The central part of the method is the evaluation of the distribution of termination rates in the balance equations. From an adopted functional form of the termination rate constant, the moment equations are derived. For evaluating the moments of the termination rate distribution an approximate reconstruction of the radical chain length distribution using Laguerre polynomials is proposed. The calculation method can handle termination by disproportionation and combination simultaneously and allows easily to take into account diffusioncontrolled initiation, propagation and chain transfer reactions. The usefulness of the method is illustrated by simulating the bulk polymerization of methyl methacrylate and styrene. The calculated results of conversion, molecular weight averages (M _n,M _w,M _z and M _z+1) and polydispersity are in good agreement with the reported experimental data.     

Ethylene polymerization over supported titanium‐magnesium catalysts: Effect of polymerization parameters on the molecular weight distribution of polyethylene

The data on the effects of polymerization duration, cocatalyst, and monomer concentrations upon ethylene polymerization in the absence of hydrogen, and the effect of an additional chain transfer agent (hydrogen) on the molecular weight (MW), molecular weight distribution (MWD), and content of vinyl terminal groups for polyethylene (PE) produced over the supported titanium‐magnesium catalyst (TMC) are obtained. The effects of these parameters on nonuniformity of active sites for different chain transfer reactions are analyzed by deconvolution of the experimental MWD curves into Flory components. It has been shown that the polymer MW grows, the MWD becomes narrower and the content of vinyl terminal groups in PE increases with increasing polymerization duration. It is assumed to occur due to the reduction of the rate of chain transfer with AlEt₃ with increasing polymerization duration. The polydispersity of PE is found to rise with increasing AlEt₃ concentration and decreasing monomer concentration due to the emergence of additional low molecular weight Flory components. The ratios of the individual rate constants of chain transfer with AlEt₃, monomer and hydrogen to the propagation rate constant have been calculated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高分子吸水剂的辐射聚合及其性能研究

利用^60Coγ射线引发辐射聚合,合成了聚丙烯酸钠、聚丙烯酸-丙烯腈、聚丙烯酸-醋酸乙烯、聚乙烯醇接枝丙烯酸等几种高分子吸水剂,考察了辐射剂量对单体聚合和吸水倍数的影响,并对所合成高分子吸水剂的吸水特性进行了研究。     

Emulsion polymerization of tetrafluoroethylene: effects of reaction conditions on the polymerization rate and polymer molecular weight

The emulsion polymerization of tetrafluoroethylene (TFE) was carried out in a semibatch reactor using a chemical initiator (ammonium persulfate) and a fluorinated surfactant (FC-143). The effects of the reaction condition were investigated though the polymerization rate, molecular weight of polytetrafluoroethylene (PTFE), and stability of the dispersion. The emulsion polymerization of TFE was different from conventional emulsion polymerization. The polymerization rate was suppressed when the polymer particles were significantly coagulated. The polymerization rate increased with operating temperature, surfactant concentration, and agitation speed, due to the enhanced stability of the polymer particles. However, once the parameter value was reached, the rate decreased due to the coagulation of the particles. Stable PTFE dispersion particles were obtained when the surfactant concentration was in the range between 3.48 × 10⁻³ and 32.48 × 10⁻³ mol/liter, which is below critical micelle concentration (CMC). The molecular weight of the PTFE obtained was a function of the surfactant and initiator concentrations, and the polymerization temperature. The molecular weight increased as each parameter decreased. This is against the phenomena observed in a conventional emulsion polymerization. A stable PTFE dispersion polymer having a high molecular weight was obtained by optimizing the reaction conditions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 777–793, 1999     

高分子量水溶性疏水缔合聚合物的合成条件研究

对合成AM/AHAC二元共聚物的引发体系进行了筛选,研究发现,用K2S2O8-DMAAM引发体系合成的聚合物相对分子量高于其它引发体系,并在此基础上进一步考察了DMAAM浓度、单体浓度、反应温度及反应时间对聚合物分子量的影响。结果表明,单体浓度为20%、K2S2O8浓度为80 mg/L,DMAAM浓度为60 mg/L,反应温度为30℃,反应时间为6 h条件下,合成的聚合物分子量较高。     

Integration of CFD and polymerization for an industrial scale cis-polybutadiene reactor

A computational fluid dynamics (CFD) approach, coupled with anionic polymerization kinetics, was used to investigate the solution polymerization in a 12?m³ industrial scale cis-polybutadiene reactor. The kinetic model with double catalytic active sites was integrated with CFD by a user-defined function. The coupled model was successfully validated by the plant data and then used to investigate the key operating variables. Also, predictions of CFD model were compared with those of continuous stirred tank reactor (CSTR) model. Although the reaction mixture is well mixed in the middle and at the top of the reactor, there exists a poor mixing feeding zone at the bottom, which leads to serious deviations from the ideal CSTR. The polymerization process with nonideal mixing is very sensitive to the inlet temperature and the feeding rate. Enhancing the mixing performance in the feeding zone could be an effective way to improve the product quality.     

聚合条件对P（AN-co—IA）分子质量分布影响的研究

采用凝胶色谱（GPC）法测定了丙烯腈与衣康酸共聚物P（AN—co—IA）的重均分子质量和数均分子质量,并通过已知聚丙烯腈的重均分子质量数据和数均分子质量数据对所测的分子质量进行校正,进一步计算得到共聚物的多分散系数。同时研究了引发剂用量、单体浓度、聚合温度、聚合时间对P（AN—co—IA）分子质量分布的影响。研究结果表明,P（AN-co-IA）分子质量分布随引发剂用量的增大、聚合单体浓度的增加而变宽,与聚合反应温度、聚合反应时间无明显的变化趋势。     

Gas‐phase polymerization of butadiene. Data acquisition using minireactor technology and particle modeling

Minireactor technology has been used for kinetic studies on polymerization kinetics, phase equilibrium, and mass transfer on a very small scale. There is a nonlinear influence of temperature and pressure on the polymerization rate. The phase equilibrium can be described by a Flory–Huggins approach, with a temperature‐dependent interaction parameter. The diffusion coefficient seems to be slightly pressure dependent, and the temperature dependence can be described with an Arrhenius equation. A simple formal kinetic scheme with formation of active sites, chain propagation, chain transfer to cocatalyst, and deactivation of active sites has been applied. This kinetic scheme was implemented in two different models; they are, a particle model taking into account mass transfer and a simple chemical model with no mass transfer. In principle, both models describe the experimental results for rate and molecular weight distribution equally well, with rate constants of the same magnitude. Molecular weight distributions calculated by the chemical model are narrower. However, the chemical model gives no explanation for the experimental observed rate dependence on catalyst particle size. With increasing catalyst activity, the differences between both models become more significant and the particle model becomes more and more important. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 270–279, 2003     

Kinetic model for lonic polymerization initiated by difunctional initiator with monomer transfer

The kinetics of difunctional ionic polymerization with monomer transfer and without assumption of instantaneous initiation is studied theoretically. The set of kinetic differential equations is rigorously solved by way of graphical theory. Expressions for the molecular weight distribution (MWD) function, the number- and weight-average degrees of polymerization, and the distribution of functionality are obtained. A procedure is proposed for calculating the MWD curve and the values of other molecular parameters.     

高转化率乳聚丁苯橡胶聚合过程中乳液相对分子质量分布与粒径分布考察

采用中石油吉化分公司乳聚丁苯橡胶高转化率大生产配方,考察了实验室聚合反应釜聚合反应单体转化率随反应时间的变化,采用激光粒度分析仪和凝胶渗透色谱仪测定了聚合反应不同单体转化率的胶乳的粒径分布与分子质量分布,结果表明：胶乳粒径呈正态分布,粒径主要集中分布在0.1μm附近,胶乳的平均粒径随反应时间的延长逐渐增大,但是增加的幅度越来越小;聚合反应时间在11 h前（即转化率小于72%）,胶乳的重均分子质量、Z均分子质量一直增大,而数均分子质量变化无明显规律;而分子质量分布宽度指数随反应的进行变小,表明调整的高转化率配方合成的丁苯橡胶可有效改善聚合生成的胶乳粒径分布。     

Mechanistic study of boron trifluoride catalyzed ε‐caprolactone polymerization in the presence of glycerol

Boron trifluoride catalyzed ε‐caprolactone polymerization in the presence of glycerol can produce poly(ε‐caprolactone) with a high weight‐average molecular weight and a broad molecular weight distribution. This article reports an investigation of the polymerization mechanism to determine the formation of these molecular weight features through a study of the polymerization kinetics and the molecular structure with NMR. The polymerization proceeds via an activated monomer mechanism, resulting in polymer molecules with hydroxyl chain ends. The broad molecular weight distribution can be attributed to the etherification reactions between hydroxyl chain ends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3900–3906, 2006     

A multistep method for steady-state Monte Carlo simulations of polymerization processes

Identifying the microscopic information of polymers is of great significance for polymerization processes. Monte Carlo (MC) simulation is a powerful tool to predict the microscopic structure of polymers. Currently, most MC methods are designed for dynamic polymerization processes based on time evolution. The study on MC simulation for steady-state processes is scarce and current approaches face challenges in addressing complex mechanisms. In this work, a multistep method is proposed for the steady-state MC simulation. By introducing the “buffer pool” concept, the proposed method is computationally efficient and flexible to derive accurate predictions for processes with various polymerization mechanisms. Three applications with increasing complexity in the kinetic mechanisms, including both linear and branching polymerizations, are presented to demonstrate the applicability of the proposed method.     

Bottleneck for reactive molar mass in the polymerization of propylene oxide initiated with potassium t‐butoxide

The anionic polymerization of propylene oxide was investigated with potassium t‐butoxide as an initiator, and the solvent hexamethyl phosphoric triamide was used in controlling experiments. The relative molar mass limit of the products was determined as about 2700, and the C?C double bond was found to exist by NMR. In situ Fourier transform infrared spectroscopy was used to monitor the whole polymerization process until the absorbance reached a constant value and the system reached equilibrium. However, propylene oxide still existed in the system, and alkoxide was detected in the reaction system by ²³Na‐NMR. On the basis of these results, we deduced that the residual alkoxide was not active enough to initiate propylene oxide polymerization in the near end of the polymerization. Therefore, there might have been another factor that limited the increase of the relative molar mass of poly(propylene oxide) in addition to chain transfer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009