聚氨酯预聚体——可聚合乳化剂用于MMA乳液聚合动力学及聚合稳定性研究

将合成的聚氨酯预聚体可聚合乳化剂（APUA）用于甲基丙烯酸甲酯（MMA）乳液聚合体系中，研究了不同引发剂体系和乳化剂对聚合体系的聚合稳定性和动力学影响，并与SDS乳化剂进行了对照。结果显示，用油溶性引发剂（AIBN）和水溶性引发剂（K2S2O8）都能引发该体系的聚合反应，而且聚合速率和转化率都相当高。用AIBN作引发剂时，APUA和SDS两种乳化所对应的动力学曲线不同，但APUA比SDS的聚合速率大得多，其分别类似于微乳液聚合（miniemulsion)和微悬浮聚合（microsuspention)，且聚合过程中会产生一定的凝胶。当乳化剂APUA用量适合时，凝胶量极少，聚合体系是稳定的；而当用K2S2O8作引发剂时，两乳化剂对应动力学曲线相似，聚合过程不产生凝胶。但当引发剂用量较大并以APUA作乳化剂时，在聚合过程中会出现全部粒子突然粗化现象，而以SDS作乳化剂没有出现这一现象。     

有机硅氧烷改性丙烯酸酯乳液的聚合稳定性分析

在用乳液聚合合成有机硅改性丙烯酸酯微乳液过程的基础上，着重考察了有机硅氧烷种类及用量、有机硅氧烷的加入方式、乳液的pH值以及聚合温度等对有机硅改性丙烯酸酯微乳液聚合过程稳定性的影响。实验结果表明，采用含异丙氧基取代基的硅烷有助于乳液聚合体系的稳定；并且控制硅氧烷用量和聚合体系的pH值、采用后交联技术有助于提高有机硅改性丙烯酸酯乳液聚合过程的稳定性。     

聚甲基丙烯酸甲酯-丁二烯-苯乙烯核壳结构乳液聚合过程表面张力研究

研究了聚甲基丙烯酸甲酯－丁二烯－苯乙烯（ＭＢＳ）核壳结构乳液聚合过程表面张力。发现丁苯乳液聚合反应过程中,体系的表面张力增大,加入电解质ＫＣｌ后,体系表面张力增加幅度增大。ＭＢＳ接枝聚合过程中,体系的表面张力降低;加入交联剂二乙烯基苯,体系的表面张力增大。     

激光在线监测无皂乳液聚合

当激光束通过乳液时其吸光度与乳液浊度有关，而浊度又与乳液粒子直径、浓度相关，在无皂乳液聚合过程中，由于体系的稳定性较差，若加料速度不适当，很容易在聚合初期出现乳液浊度陡增甚至凝胶。本研究利用氦氖激光器分别对苯乙烯、丙烯酸酯、醋酸乙烯酯等单体的无皂乳液聚合实施监测，即通过吸光度变化来控制加料速度，使乳液吸光度保持平缓变化，也就是在聚合初期使乳液粒子浓度保持在适当水平，从而避免因小粒子溶胀聚并产生凝胶，制得了具有良好稳定性的无皂聚合乳液。     

含环氧基三元共聚乳液的合成与性能

本文研究了甲基丙烯酸甲脂＝丙烯酸丁酯－甲基丙烯酸缩水甘油酯三元乳液共聚合体系中，乳化剂，引发剂，聚合温度和官能团单体ＧＭＡ含量对聚合过程转化率的影响及它们对乳液粘度和电解质稳定性的影响。聚合动力学研究表明，本聚合体系与经典乳液聚合理论存在某些偏差：反应速度Ｒｐ随乳化剂浓度的增加而增大，到某一值后又随乳化剂浓度增大而减小。     

PHMS为反应性助稳定剂的苯乙烯细乳液聚合

以含氢聚硅氧烷(PHMS)为反应性助稳定剂,研究苯乙烯(St)细乳液聚合。表征了细乳液聚合产物的结构,探讨了PHMS与St接枝共聚反应机理,考察了不同体系聚合产物接枝量、接枝产物中PHMS的含量以及不同乳液聚合反应稳定性和乳胶耐盐稳定性。通过红外和核磁分析结果表明,除St均聚反应外,PHMS通过游离基加成反应与St生成了接枝共聚物。细乳液体系中,PHMS用量由5%质量分率增加到20%,聚合产物接枝量和接枝产物中PHMS质量百分比先增大后降低。当PHMS质量分率为10%时,聚合产物接枝量和接枝产物中PHMS质量百分比出现峰值,分别为73.35%和8.46%。与普通乳液聚合反应相比,细乳液聚合过程中凝胶量减少,细乳液聚合产物接枝量和接枝产物中PHMS质量分率的增加,乳胶耐盐稳定性增强。     

反相微乳液聚合

介绍了反相微乳液聚合方法的建立及体系组成、乳化剂选择、聚合过程及聚合物的表征、聚合反应动力学及机理，以及反相微乳液聚合的特点及应用。指出，提高反相微乳液聚合体系中的固含量将是今后的重点及难点。     

电解质对真石漆用乳胶性能的影响

乳液聚合过程受单体结构、乳化剂、引发剂、聚合工艺的影响,此外还受乳液聚合体系中电解质的影响。系统地研究了电解质的用量对乳胶凝胶率、粒径分布、钙离子稳定性、机械稳定性以及耐水白性的影响。     

超浓乳液聚合氧化还原引发体系的研究进展

介绍了超浓乳液的三个主要特点。从体系状态，单体含量，聚合速度，相对分子质量，聚合物形态和设备利用率方面比较了超浓乳液聚合与传统乳液聚合及本体聚合的区别。指出超浓乳液聚合中使用热分解引发剂所产生的问题及使用氧化还原引发剂的原因。还简单介绍了氧化还原引发体系的分类，回顾了前人在超浓乳液聚合工作中不同单体体系使用的氧化还原引发剂的情况，总结了不同单体体系中氧化剂还原剂的最佳配比，以及它们对动力学、相对分子质量的影响。最后展望了超浓乳液聚合新的发展方向。     

在无机SiO2纳米粒子存在下的苯丙乳液共聚合

本文研究了在无机SiO2纳米粒子存在下的苯丙乳液共聚合，首先选择了能使苯丙乳液稳定存在的乳化剂体系。然后研究了温度和SiO2的加入对聚合过程转化率的影响。转化率数据实验表明SiO2的加入对聚合过程有阻聚作用。单体的转化率会降低，SEM照片证明SiO2纳米粒子已经进入到了苯丙乳液粒子中，而且SiO2的加入对乳液制成的膜的断面形态有一定影响，但是实验发现在无机SiO2纳米粒子存在下，苯丙乳液共聚合时会有较多残渣出现，本文对此现象进行了研究，同时对制成的复合材料进行了力学性能和热学性能的测定，最后对聚合过程中出现较大残渣颗粒的现象通过改进乳液聚合过程进行了有效的改善。     

模糊控制器在丙烯聚合反应中的应用

针对聚合反应温度具有大时变性、强非线性、纯时滞性的动态特性和现有聚合反应控制方案的不足,结合模糊控制表达能力强、适应复杂系统、鲁棒性好的特点,在分析丙烯聚合工艺基础上提出了一种双输入双输出结构的新型模糊控制器,有效实现聚合反应全过程中热水阀和冷水阀开度大小的自动控制和适时切换。通过MATLAB SIMULINK仿真验证了该控制方法能实现聚合反应升温段的快速升温无超调和过渡段的平稳过渡,且恒温段控制精度在±0.2℃。     

直接挤出成型加工用硬质聚氯乙烯专用树脂

在2、10和70L聚合釜中对氯乙烯悬浮聚合工艺与树脂颗料形态的关系进行了研究,对添加的助剂进行了筛选和匹配,确定了静态混合接枝聚合技术及两段悬浮聚合工艺。指出：该 用树脂生产技术特点是将PVC加工中所需的各种助剂在聚合期间全部加到聚合釜中,且非常均匀地散到PVC颗粒内部发挥相应的作用,树脂颗粒形态规整,吸油率适中,干流性好,易于加工成型;同时能有效地改善生产环境,是挤出成型加工硬质制品的理想专用树脂,对PVC工业的发展具有重要意义。     

Continuous Dosing of a Fast Initiator during Suspension Polymerization of Vinyl Chloride for Enhanced Productivity: Mathematical Modeling and Experimental Study

An adopted mathematical model was developed to reduce the batch time required for the suspension polymerization of vinyl chloride in order to improve the productivity by continuous dosage of a fast initiator during polymerization reaction. The model was accompanied by a particle swarm optimization (PSO) algorithm, so as to optimize the initiator dosage rate during the process for a certain conversion. A pilot scale reactor was employed to verify the mathematical model predictions. This showed that the model predictions are in very good agreement with the experimental data. A proper initiator dosage trajectory during the course of the reaction was obtained in such a way that the reaction rate over the course of polymerization was constant and corresponded to the maximum rate in the conventional case (non-continuous addition of a mild initiator). The maximum reduction in reaction time relative to conventional polymerization for the predefined conversion was 53%. Analyzing the molecular characteristics of the samples showed that the molecular characteristics of the final poly(vinyl chloride) (PVC) product remained relatively unchanged under an optimum initiator dosage trajectory compared with the conventional process.     

Redox initiated free radical polymerization of 4‐methylstyrene

Studies of the thermally initiated polymerization of 4‐methylstyrene using alkylperoxide in conjunction with cobalt and tertiary amine catalysts are reported. Addition of cobalt salts leads to a facile low temperature initiation of the polymerization process. The polymerization process was investigated using differential scanning calorimetry [DSC] and vibrating probe rheological measurements. Color changes which occur when the cobalt complex and peroxide are combined were studied using UV‐visible spectroscopy. The kinetics of polymerization was investigated using two different cobalt complexes. The initiation step in the polymerization is the conversion of the cobalt (II) to cobalt (III). The presence of the tertiary amine does not affect the oxidation state of the cobalt complex. The cobalt (III) complex gives a better rate of conversion than the cobalt (II) complex. The polymerization process is discussed in terms of redox reaction between the cobalt complex and the alkyperoxide. At low temperatures, the rate of conversion obeys simple Arrhenius kinetics. At higher temperatures the effects of gelation and catalysts inhibition influence the polymerization process. The polymerization process is sensitive to the level of available oxygen during the initiation step and inhibition by aldehyde is observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

An ESR study of the film formation steps of vapor deposition polymerization of polyamic acid

A film of polyamic acid is formed by vapor deposition polymerization of pyromellitic dianhydride (PMDA) and 4,4′-diaminodiphenyl ether (ODA). We have taken ESR spectrum during the polymerization process and compared it with the ESR spectrum of films obtained from solution polymerization. In the intermediate polymers during vapor deposition polymerization, the amide bond (? CONH? ) is coplanar with the benzene ring and two protons in the PMDA molecule. This intermediate polymer has one unpaired electron that interacts with the two nitrogen nuclei equally. On the other hand, in the polymer obtained by solution polymerization, the amide bond and the benzene ring of PMDA are not coplanar. In this polymer, too, some of the molecules have an unpaired electron that seems to have almost no coupling with NH groups. These results imply that the polymer formation via vapor deposition proceeds through different intermediates and different molecular configurations from that via the solution process.     

Influence of Process Parameters on the Conductivity and Surface Morphology of Polypyrrole Films

Influence of electrochemical process parameters such as monomer and electrolyte concentrations, current density, pH of the electrolyte, and type of electrolyte have been studied during polymerization of polypyrrole (Ppy). The changes in the conductivity of synthesized Ppy film for different electrolytes were observed by chronopotentiograms recorded during the electrochemical polymerization and it was confirmed by measuring it using four probe techniques. It was found that the electrochemical process parameters have a considerable influence on the conductivity of the film. The Ppy film was synthesized on a platinum substrate by electrochemical polymerization with different electrolytes such as potassium nitrate, sodium nitrate, sulphuric acid, hydrochloric acid, potassium chloride, sodium chloride, oxalic acid, and sodium salicylate, under galvanostatic condition over a wide range of pH of the reaction medium and applied current density. The different concentration ratios of pyrrole and sodium nitrate were considered during synthesis of Ppy films. It has been observed that the polymerization potential increases with the pH and applied current density. One could synthesize Ppy film with very good surface morphology and conductivity with optimized process parameters. The characterization of synthesized Ppy film was done by electrochemical technique, electrical conductivity, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM).     

Side reactions in the synthesis of triblock copolymers of nylon‐6 with telechelic oligomers

BACKGROUND: The polymerization of hexanelactam (HL) is complicated by numerous side reactions: chain transfer to monomer, termination of the polymer chain, exchange as transamidation and formation of β‐ketoimides and β‐ketoamides. The generation of by‐products and their effect on the anionic polymerization of HL in the bulk in the presence of functionalized tetrahydrofuran oligomers as polymeric activators (PACs) were investigated. RESULTS: In order to consider how side reactions influence the process of HL polymerization, qualitative and quantitative determination of the by‐products obtained and their exhaustion were carried out. An investigation of the polymerization kinetics and the formation of low molecular weight by‐products through the polymerization was performed. The products are further involved in the polymerization process and consumed until an equilibrium level is reached. The mechanism of their generation is discussed. These processes were followed during the first polymerization stage by means of gel permeation chromatography. A mechanism of by‐product formation and consumption is proposed. CONCLUSION: The investigation of the polymerization kinetics and the formation of low molecular weight by‐products through the polymerization has shown that the side reaction yields oligomeric HL‐based products. The products are further involved in the polymerization process and consumed until an equilibrium level is reached. The equilibrium values depend on the HL/PACs ratio. Copyright © 2008 Society of Chemical Industry     

Development of AAS resin by the emulsion–suspension polymerization method

In order to improve the weatherability of acryonitrile—styrene—butadiene rubber graft polymer (ABS resin), an attempt was made to develop a resin (AAS resin) in which acrylic rubber of good weatherability was used instead of butadiene rubber. First, by copolymerizing dicyclopentenyl-methacrylate (DCP-MA,3%) with butyl acrylate, crosslinked acrylic rubber was obtained. This also introduced grafting sites into the rubber. Next, methods of graft copolymerizing styrene and acrylonitrile with this rubber were examined. An emulsion–suspension polymerization method was developed in which the initial stage of the polymerization, emulsion polymerization, changed into suspension polymerization during the process. By this method of polymerization, rubber particles were combined and enlarged, bringing about a graft-type resin with high impact resistance. This polymerization method is industrially useful because particle-shaped resins are obtained without the need of a salting-out process. The AAS resin, obtained in this way, has much improved weatherability over ABS resin and shows strength equal to that of ABS resin. © 1992 John Wiley & Sons, Inc.     

乙丙橡胶中试聚合工艺物料平衡关系

乙丙橡胶中试溶液聚合工艺是聚合反应气相与脱气系统气相汇总形成循环物流,循环物流中丙烯的组成是聚合物结构的主导因素,丙烯的相变是聚合反应温度的控制关键,因此,明确聚合、脱气、压缩环节丙烯的含量和状态,是物料衡算、热量衡算、动量衡算的关键因素,更是设备设计、工程控制的决定性因素。本文通过根据乙丙橡胶聚合工艺特点,明确聚合釜气液相乙烯、丙烯的物料分配原则,结合聚合反应热换热关系,通过对丙烯循环量、溶解量的计算,确定了聚合工艺物料状态及衡算关系。     

Toward a better understanding of the emulsion polymerization of butadiene. I. Continuous conductivity measurements

Continuous conductivity measurements were performed during the batch emulsion polymerization of butadiene along with kinetic and particle size measurements. The critical monomer conversion was obtained around 55% and the rate of polymerization was correlated to the surfactant concentration with an exponent of 0.35 which was not in agreement with the exponent offered by Smith and Ewart. In addition, the evolution of some particle‐related quantities such as particle size and number of particles during the three intervals of the emulsion polymerization and their agreements with Smith‐Ewart mechanism were investigated. The behavior of conductivity in the emulsion polymerization of butadiene normally containing a buffering agent was found to be completely different from the unbuffered one. Comparison of the conductivity profiles with the kinetic and particle‐related quantities represented that the conductivity of the reaction mixture is very sensitive to the changes in the particle size so that any small change in the forms of nucleation, growth, and coagulation is clearly observed in the conductivity profiles. Furthermore, the conductimetric data are capable of determining some important points during the polymerization such as the beginning of the reaction that can be important from the industrial process control point of view. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45262.