苯乙烯连续塔式本体聚合工业过程模拟

对苯乙烯工业本体后聚合过程进行了模型化研究。建立了实验模拟装置，对塔式反应器的混合模式进行了分析。结果表明，后聚釜中的每段双螺带搅拌部分可视为1或2个全混流(CST)反应器模型；利用工业装王采集的数据对不同模型进行了对比，选取了CST与平推流(PF)5段串联的反应器模型；对宏观转化率和平均相对分子质量进行了验证，模拟结果和工业数据相吻合。     

氯乙烯聚合尾气回收工段高沸塔的模拟优化

采用流程模拟软件Aspen Plus对氯乙烯尾气回收工段高沸塔进行模拟分析,并对运行参数进行了优化,确定了理论板数为48块,进料位置为第32块理论板,回流比为0.8。并根据上述结果对实际生产进行调整,经估算该套聚合尾气回收装置可取得经济效益6 326.5万元/a。     

Alternatives for multiobjective optimization of a polymerization process

The optimal control policies for a polymerization process, particularly for batch free‐radical polymerization of methyl methacrylate, were determined using a multiobjective optimization technique. The process objectives considered in the optimization include monomer conversion, polydispersity index, polymerization degree, and total reaction time, weighted and combined in a scalar objective function. The decision variables were the initial concentration of the initiator and the temperature represented by isothermal steps. For solving the optimization problem, several methods based on sequential quadratic programming and a genetic algorithm were used and compared. Combining them into a hybrid method (the genetic algorithm provided the initial values for the traditional iterative method) led to the best results. The aims of this study were to develop an approach for optimizing the polymerization process and to describe alternatives for formulating and solving this problem, emphasizing the importance of user decision in choosing solutions based on technological criteria. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3680–3695, 2006     

Development of new concepts for the control of polymerization processes: Multiobjective optimization and decision engineering. I. Application to emulsion homopolymerization of styrene

This article deals with the development of a multicriteria analysis, and its application to the optimization of batch emulsion polymerization processes. This new approach in the domain of polymer reaction engineering illustrates how a multiobjective optimization aided by a genetic algorithm and using the Pareto concept of domination is useful. In this process (emulsion homopolymerization of styrene), several objectives were simultaneously required, e.g., a high quality of the resulting products together with a high productivity. The aim of this study was to find the optimal experimental conditions to obtain simultaneously the minimum reaction time and designed values for both average molecular weights and particles size. To do that, an adapted mathematical model, able to describe all the process physicochemical phenomena, was been first elaborated. The multicriteria analysis then gave a set of nondominated points with conflicting criteria. A decision support system was then developed and applied to rank the Pareto solutions set and to propose some good solutions by taking into account the decision maker's preferences. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2383–2396, 2003     

PET连续聚合工艺流程优化改造

采用将五釜流程改为四釜流程的方法,即以酯化预聚塔一个反应器取代五条工艺流程的第二酯化釜和第一预缩聚釜两个反应器,对PET聚合工艺流程优化,改造后的PET单线生产能力由160t/d提高到200 t/d,其单耗PTA由改造前的865 kg/t降至863 kg/t,EG由338 kg/t降至334 kg/t,降低了成本,提高了产品质量。     

A study on new polymerization technology of styrene

The classic polymerization technology of polystyrene is a high‐cost and nonfriendly environmental technology. Furthermore, the weight‐average molecular weight of polystyrene is hard to enhance up to 400,000 in the classic polymerization technology. The disadvantages limit the growth rate of polystyrene. The solution for increasing the growth rate of polystyrene lies in new technology. The reactive extrusion process of polystyrene was studied in detail and the whole reactive extrusion process of polystyrene was obtained. By means of controlling the flow rate of styrene and the initiator and the screw rotational speed, samples of polystyrene with different molecular weights were synthesized by the twin‐screw extruder. The properties of synthesized polystyrene with different molecular weights were studied; the mechanic properties of polystyrene will increase with an increase of the weight average molecular weight of polystyrene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2130–2135, 2002     

Multiobjective optimization of the continuous casting process for poly (methyl methacrylate) using adapted genetic algorithm

The nondominated sorting genetic algorithm (NSGA) has been used to optimize the operation of the continuous casting of a film of poly (methyl methacrylate). This process involves two reactors, namely, an isothermal plug flow tubular reactor (PFTR) followed by a nonisothermal film reactor. Two objective functions have been used in this study: the cross‐section average value of the monomer conversion, x̄_mf , of the product is maximized, and the length, z_f , of the film reactor is minimized. Simultaneously, the cross‐section average value of the number‐average molecular weight of the product is forced to have a certain prescribed (desired) value. It is also ensured that the temperature at any location in the film being produced lies below a certain value, to avoid degradation reactions. Seven decision variables are used in this study: the temperature of the isothermal PFTR, the flow rate of the initiator in the feed to the PFTR (for a specified feed flow rate of the monomer), the film thickness, the monomer conversion at the output of the PFTR, and three coefficients describing the wall temperature to be used in the film reactor. Sets of nondominating (equally good) optimal solutions (Pareto sets) have been obtained due to the conflicting requirements for the several conditions studied. It is interesting to observe that under optimal conditions, the exothermicity of the reactions drives them to completion near the center of the film, while heat conduction and higher wall temperature help to achieve this in the outer regions. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1439–1458, 2000     

Effects of short chain alcohols on the styrene emulsion polymerization

The effects of a series of short chain alcohols, 1‐butanol (C₄OH), 1‐pentanol (C₅OH), and 1‐hexanol (C₆OH), on the styrene (ST) emulsion polymerization mechanisms and kinetics were investigated. The CMC of the ST emulsions stabilized by sodium dodecyl sulfate (SDS) first decreases rapidly and then levels off when the C_iOH (i = 4, 5, or 6) concentration ([C_iOH]) increases from 0 to 72 mM. Furthermore, at constant [C_iOH], the CMC data in decreasing order is CMC (C₄OH) > CMC (C₅OH) > CMC (C₆OH). The effects of C_iOH (i = 4, 5, and 6) on the ST emulsion polymerization stabilized by 6 mM SDS are significant. This is attributed to the reduction in CMC by C_iOH, the different oil–water interfacial properties, the different concentrations of monomer within latex particles, and the different effectiveness of SDS/C_iOH in stabilizing latex particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4406–4411, 2006     

Heterogeneous bulk polymerization of styrene in the presence of polybutadiene: Calculation of the macromolecular structure

A mathematical model is presented that simulates the polymerization of styrene in the presence of polybutadiene (PB) for producing high‐impact polystyrene (HIPS) via the heterogeneous bulk process. The model follows the polymerization in two phases; and calculates in each phase the main reaction variables and the molecular structure of the three polymeric components: free polystyrene (PS), unreacted PB, and graft copolymer. Two polymerizations (at 90 and 120°C) were carried out and simulated. The model was validated with measurements of the monomer conversion, the grafting efficiencies, and the average molecular weights. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3023–3039, 2006     

Novel monotitanocene and methylaluminoxane catalyst for syndiospecific polymerization of styrene

Syndiotactic polystyrene (sPS) was synthesized with a novel monotitanocene complex of η⁵‐pentamethylcyclopentadienyltri‐4‐methoxyphenoxy titanium [Cp*Ti(OC₆H₄OCH₃)₃] activated by methylaluminoxane (MAO) in different polymerization media, including heptane, toluene, chlorobenzene, and neat styrene. In all cases bulk polymerization produced sPS with the highest activity and molecular weight. Solution polymerization produced much better activity in heptane than in the other solvents. Using a solvent with a higher dipole moment, such as chlorobenzene resulted in lower activity and syndiotacticity because of the stronger coordination of solvent with the Ti(III) active species, which controlled syndiospecific polymerization of styrene. With bulk polymerization at a higher polymerization temperature the Cp*Ti(OC₆H₄OCH₃)₃–MAO catalyst produced sPS with high catalytic activity and molecular weight. The external addition of triisobutylaluminum (TIBA) to the Cp*Ti(OC₆H₄OCH₃)₃–MAO system catalyzing styrene polymerization led to significant improvement of activity at a lower Al:Ti molar ratio, while the syndiotacticity and molecular weight of the yields were little affected. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1243–1248, 2001     

Evaluation of the confinement effect of nanoclay on the kinetics of styrene atom transfer radical polymerization

The grafting through method was employed to study the effect of nanoclay confinement on the atom transfer radical polymerization (ATRP) of styrene. An ammonium salt containing a double bond on its structure was used as a clay modifier. Employing ATRP to polymerize styrene in the presence of modified montmorillonite resulted in a finely well‐defined polystyrene nanocomposite. The gas chromatography (GC) results showed the linear increase of ln(M₀/M) versus time, which indicated the controlled behavior of the polymerization. Another confirmation of the living nature of the polymerization was the linear increase of molecular weight against monomer conversion concluded from the gel permeation chromatography (GPC) data. Nanoclay exerted acceleration on the polymerization of free polystyrene chains. The polydispersity indexes of polymer chains increased by the addition of nanoclay. In the case of clay‐attached polystyrene chains, number and weight‐average molecular weights were lower than that of freely dispersed polystyrene chains. The polydispersity index of the clay‐attached chains was higher in respect to the freely dispersed polystyrene chains. The living nature of polymer chains was more elucidated by Fourier transform infrared spectroscopy (FTIR). Exfoliation of the clay layers in the polymer matrix of polystyrene nanocomposite containing the lowest amount of nanoclay has proven by Transmission Electron Microscopy (TEM). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Identification of mixing parameters in agitated pulp chests: A continuous time domain approach

Parameter identification is quite challenging in mixing, which is extensively employed in chemical process industry. Agitated pulp chests are more difficult to characterize because they handle non-Newtonian pulp suspensions and non-ideal flows such as short circuiting, recirculation and channeling. In the present study, we characterize the agitated pulp chests in the continuous time domain, which obviates the restrictions imposed by the discrete time approach. For this purpose, a robust and efficient hybrid genetic algorithm is utilized along with a differential-algebraic model of mixing. Necessary derivatives including auxiliary differential equations are obtained for gradient search. Using realistic large sets of mixing data, both the algorithm and the model are successfully validated before characterizing laboratory-scale agitated pulp chests. Superior characterizations are obtained compared to those yielded by the discrete time domain approach. This outcome highlights the benefit of the continuous time domain approach developed in this work.     

Modeling of the pervaporation process for isobutanol purification from aqueous solution using intelligent systems

In this study, intelligent systems (ANN-GA and GMDH) was employed to develope a model based on experimental data to predict the performance of the pervaporation process. The ANN system was coupled with the genetic algorithm (GA) to choose initial connection weights and biases of the multi-layer feed forward neural network (FFNN). The input parameters were the feed concentration, membrane thickness, and Reynolds number, while the outputs were total flux and permeate concentration. The RMSE of the estimated total flux for the ANN-GA and GMDH were 0.09170 and 0.0903, respectively. Also, the RMSE of estimated permeate concentration for the ANN-GA and GMDH were 0.0994 and 0.0975, respectively. The results indicated that the models had sufficient accuracy, but that GMDH could provide a better outcome. Finally, the relative importance of input variables on the network outputs was determined. Sensitive analysis showed that the membrane thickness and feed concentration are the most effect on the total flux and permeate concentration, respectively. Other variables also have important effect on the PV process and cannot be ignored.     

A kinetic study of novel bimetallic titanocene catalyst for syndiospecific styrene polymerization

A kinetic study of a syndiospecific polymerization was performed with two kinds of catalysts: Cp*Ti(O(C₆H₄)CMe₂(C₆H₄)O)TiCp* [bimetallic system] and Cp*Ti(OMe)₃ [monometallic system]. The purpose of this study was to determine the reasons behind the high activity of a bimetallic catalyst system. The active site structures of the two kinds of catalysts appears to be similar to the cationic Ti [III] species having η⁵‐pentamethylcyclopentadienyl ligand, while the rate of the activation process of the bimetallic catalyst was found to be higher than that of the monometallic catalyst. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

塔式造粒返料影响产品养分的原因分析与流程优化

对复合肥生产过程中不合格品主要集中在改产前后的现象进行深入分析,确定筛分工序返料量变化是关键影响因素。通过增设返料皮带计量秤与造粒工序原有混合粉料计量称连锁,消除返料量变化对产品养分的影响,流程优化后一次品合格率提高2.43个百分点,每年可实现经济效益43万元,养分损耗率降低0.11个百分点,每年可节约88万元。     

Numerical modeling and experimental study of the frontal polymerization of the diglycidyl ether of bisphenol A/diethylenetriamine epoxy system

Frontal polymerization is a process in which a spatially localized reaction zone propagates through a monomer by converting it into a polymer. In particular, the heat produced during the curing process is exploited to promote the reaction of the monomer lying next to the propagating front, making this latter able to self‐sustain. This approach represents an alternative solution to traditional polymerization methods and can be successfully applied to the preparation of many polymeric materials. In this study, frontal polymerization was numerically modeled to better understand it and to provide the basis for processing simulation. A finite‐difference method was used to solve the thermal problem coupled with the equation describing the cure evolution for a reactor with a cylindrical geometry. The implicit backward time–centered space method was used. First, a one‐dimensional model, able to describe the process in an adiabatic tube, was developed. The front ignition was simulated as if it were a hot surface warming one end of the reactor to trigger reactant polymerization. The model was able to predict the formation of a reactive front advancing in the unreacted zone with a constant speed. The influence of the chemical and physical properties of the resin on process evolution was also investigated. By applying the alternate direction implicit method, a more detailed two‐dimensional model able to describe a three‐dimensional problem for a cylindrical reactor was also developed. With this model, it was possible to study the influence of boundary conditions on process evolution, considering a convective heat exchange with the environment through the reactor walls. Diglycidyl ether of bisphenol A, cured with diethylenetriamine (DETA), was used as the model system. Differential scanning calorimetry was used to produce a phenomenological model able to describe the cure process and to determine the physical properties of the resin. The validity of the approach was confirmed experimentally using a small cylindrical reactor. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1756–1766, 2005     

高塔造粒复合肥冷却新工艺

提出以地下水为冷媒预冷却空气并对空气减湿的高塔造粒复合肥冷却新工艺。介绍其工艺流程、工艺设备以及实施效果，可使物料良好冷却，保持颗粒外观圆整度，降低生产成本。     

Bulk polymerization of styrene in the presence of organomodified montmorillonite

The effect of montmorillonite (Cloisite 6A) on the bulk polymerization of styrene initiated by benzoyl peroxide (BPO) was studied by the dilatometric determination of the polymerization rates. The bulk polymerization rates increased as the montmorillonite input quantity increased. The effect became greater when the BPO concentration decreased. Under the assumption that clay participated in the radical initiation reaction of the chains, the reaction orders for clay and BPO were determined to be approximately 1.0 and 0.5, respectively. X‐ray diffraction and thermogravimetric analysis studies showed that the structure and properties of the obtained polystyrene (PS)/montmorillonite nanocomposites were greatly affected by the BPO concentration. With lower BPO concentrations, a larger interlayer distance and a higher extent of delamination for the clay were observed in the obtained PS/montmorillonite nanocomposites. The nanocomposites prepared with lower BPO concentrations also showed higher heat‐decomposition‐resistance temperatures. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1146–1152, 2005     

Effects of polymerization conditions on particle size distribution in styrene‐graphite suspension polymerization process

Suspension polymerization in the presence of graphite has been studied in order to determine the effects of some operational parameters on the particle size distribution (PSD). The results showed that, with increasing graphite content, the particle size of the polystyrene/graphite (PS/G) beads increased. Moreover, instability of the suspension polymerization system was found at high amounts of graphite. With increasing initiator concentration, the particle size of the polymer beads increased and the PSD became slightly narrower. Changing the concentration of the suspending agent proved to be an efficient way of controlling the particle size, although its increase led to a broadening of the PSD. Adding the suspending agent in two portions at different times decreased the particle size, maintained a lower concentration of suspending agent, and kept the suspension polymerization system stable. Adjusting the stirring speed proved to be a very efficient means of manipulating the PSD of the PS/G composite beads. The Sauter mean diameter decreased and the PSD was broadened with increasing stirring speed; 400 rpm was identified as an appropriate value to obtain polystyrene/graphite beads with desirable particle size and distribution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44270.