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Rheo-optic in situ synchronous study on the gelation behaviour and mechanism of waxy crude oil emulsions

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Petroleum Science 2023年第2期20卷 1266-1288页

作者： Jian Zhao Xiao-Feng Li Hang Dong Zhi-Hua Wang Young and Middle-aged Innovation Team Program of Northeast Petroleum University Energy-saving and Consumption-reducing LaboratorySurface Engineering Pilot Test Center of CNPCNortheast Petroleum UniversityDaqingHeilongjiang 163318China

An improved rheo-optic in situ synchronous measurement system was employed to investigate the gelation behaviour and mechanism of waxy crude oil emulsions. By combining transmitted natural light and reflected polarized light microscopy, a multiangle composite light source was built to achieve the simultaneous observation of wax crystals and emulsified water droplets, as well as their dynamic aggregation process. Main outcomes on the microscopic mechanism were obtained by developed microscopic image processing method. It was found that the microstructure of W/O waxy crude oil emulsion has the evolution of “individual structure--homogeneous aggregate structure--heterogeneous coaggregate structure--floc structure” during the static cooling, which results in the four stages during gelation process. Different from previous studies, the aggregation of emulsified water droplets was found to be more significant and contributes to the formation and development of the wax crystals-emulsified water droplets coaggregate, which plays a decisive role in the further evolution of the gelled microstructure. Time series microscopic images show the dynamic aggregation of emulsified water droplets and wax crystals. Two different aggregation behaviours between wax crystals and water droplets were observed. That wax crystals can not only embed in gaps between adjacent water droplets and enhance the structure, but also surround the outside of the water droplets and continue to grow resulting in the interconnection of different coaggregates to form a larger floc structure. In addition, correlation between viscoelasticity and microstructure evolution of waxy crude oil emulsions of different water contents was discussed. With increasing water contents, the microstructure is changed from wax crystal flocculation structure as the main skeleton and the emulsified water droplets embedded in it, into the aggregation of emulsified water droplets occupying the main position. When the number of wax crystals and water droplets reaches a certain ra

关键词： Waxy crude oil emulsion Rheo-optic in situ synchronous measurement gelation Microscopic mechanism Structural behaviour

gelation behavior of Antheraea pernyi silk fibroin

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Science China Chemistry 2010年第3期53卷 535-541页

作者： YAN ShuQin,ZHAO ChunXia,WU XiuFang,ZHANG Qiang & LI MingZhong National Engineering Laboratory for Modern Silk College of Textile and Clothing Engineering,Soochow University,Suzhou 215123,China National Engineering Laboratory for Modern Silk College of Textile and Clothing Engineering Soochow University Suzhou China

The sol-gel transition behavior of Antherae pernyi silk fibroin(Ap-SF) has not been systematically investigated.In this work,the influence of environmental temperature,pH,the concentration of Ap-SF,K+ and Ca2+ on the gelation time,and the structural changes of Ap-SF in sol-gel transformation were studied.The results indicated that the gelation time of the Ap-SF aqueous solution decreased with the increase of the Ap-SF concentration and environmental temperature.The sol-gel transformation of Ap-SF was much more rapid than that of Bombyx mori silk fibroin under the same conditions.The Ap-SF was sensitive to changes in the concentration of Ca2+ and K+.Upon gelation,the random coil structure of the Ap-SF was significantly transformed into the β-sheet structure.

关键词： Antheraea pernyi silk fibroin gelation sol-gel transition

gelation Mechanism of Erythromycin Ethylsuccinate During Crystallization

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Transactions of Tianjin University 2019年第2期25卷 110-117页

作者： Xiandong Su Zhenguo Gao Ying Bao Miao Guan Sohrab Rohani Qiuxiang Yin Hongxun Hao Chuang Xie Jingkang Wang School of Chemical Engineering and Technology Tianjin University Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin) Department of Chemical and Biochemical Engineering Western University

In this paper, the gelation mechanism of erythromycin ethylsuccinate(EES) during crystallization is investigated for the first time. The generated semisolid gel-like phase exhibited a 3D fibrillar network morphology and the typical rheological properties of gels. The fibers inside the gel-like phase were confirmed to be new types of EES solvates using powder X-ray diffraction, thermogravimetric analysis/differential scanning calorimetry, and gas chromatography. The gelation and crystallization regions in EES-1-propanol solid–liquid phase diagram were determined. Analyses of solvent parameters showed that moderate solvent polarity may promote EES gelation. Fourier transform infrared spectra, nuclear magnetic resonance spectra, and scanning electron microscopy analyses indicated that through intermolecular hydrogen bonds, EES and solvent molecules assembled into fibers via crystallographic mismatch branching growth. The fibers intertwined into a 3D network microstructure and formed a gel-like phase, completely immobilizing the solution.

关键词： gelation Solvate Crystallization Phase diagram Molecular self-assembly

gelation Phenomenon During Crystallization of Cefpiramide Sodium

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Transactions of Tianjin University 2019年第4期25卷 364-370页

作者： Yu Wei Qiuxiang Yin Mingxia Guo Ling Zhou Ying Bao Yongfan Yang School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin 300072China Department of Chemical Engineering Imperial College LondonSouth Kensington CampusLondon SW7 2AZUK

Unlike the adverse eff ect caused by the gelation during crystallization process, gelation of cefpiramide sodium was found to provide ideal product properties, such as a larger and more regular crystal shape. The causes of the gelation phenomenon and the mechanism of gel-crystal transition during the crystallization of cefpiramide sodium were both investigated in this work. The gel was formed due to the strapping of the solvents by the networks of cefpiramide sodium molecules. The whole gel-crystal transition process was divided into the following three stages:(1) when the temperature decreased, the system reached a metastable-state gelation;(2) the initial microcrystal in the gel grew slowly because of the low supersaturation;and (3) the gel fi nally disappeared, and a larger and more regular crystal was formed. The Hansen solubility parameters were used to analyze the eff ects of the solvents on this gelation;the analysis results can serve as guidance for solvent screening in the actual production process.

关键词： Cefpiramide sodium Crystallization gelation

A study of function mechanism of hemxamethyl tetra-amine in gelation process of uranium

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Rare Metals 2006年第Z1期25卷 343-346页

作者： GUO Wenli LIANG Tongxiang ZHAO Xingyu HAO Shaochang FU Xiaoming Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China

The UO2 ceramic microspheres are the most important materials in the spherical fuel elements for high temperature reactor (HTR). A process for preparation of UO2 kernels known as total gelation process of uranium (TGU) was developed as the production process of 10 mW HTR at Tsinghua University. The TGU process is based on the traditional sol-gel process, external gelation process and internal gelation process of uranium (EGU and IGU), which implies that the gelation action is initiated both by ammonia out of the gel particles and hemxamethyl tetra-amine (HMTA) inside the gel particles. The gelation behavior and the properties of uranium microspheres were investigated of the solution with and without HMTA. It is observed that good spherical particles can be obtained without HMTA in the sol, which indicates a more controllable and industrialized route will be set up. Contrasts between this route and the traditional EGU were also listed.

关键词： gelation process of uranium high temperature reactor (HTR) UO2 microsphere

IN SITU INTERFEROMETRIC STUDY ON THE gelation PROCESS OF POLYACRYLIC ACID GELS

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Chinese Journal of Polymer Science 2000年第4期18卷 373-377页

作者： Ying Guan Qiang Chen Xian-min Zhang Yu-xing Peng Jian Xu Polymer Physics Laboratory, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China Department of Information & Electronic Engineering, Zhejiang University, Hangzhou 310027, China Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China 中科院化学所高分子物理及化学国家重点实验室北京浙江大学浙江杭州中科院成都有机化学所四川成都

In situ interferometry was used to investigate the gelation process of polyacrylic acid (PAA) gels. The basic principle of the in situ interferometry technique is illustrated. It can give sufficient information for non-destructive and successful investigation of the whole gelation process. The effect of initiator concentration on the gelation process was studied. The polymerization rate of AA increases with increasing initiator concentration. The error arising from the thermal effect in the gelation process can be neglected.

关键词： in situ interferometry gelation polyacrylic acid

gelation of a Reversible Markov Process of Polymerization

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Acta Mathematicae Applicatae Sinica 2003年第1期19卷 87-96页

作者： DongHan Yian-linHan DepartmentofMathematics ShanghaiJiaoTongUniversityShanghai200030China DepartmentofStatistics XinjiangFinanceUniversityUrumqi830000China

Abstract In this paper a reversible Markov process as a chemical polymers reaction of two types of monomers is defined. By analyzing the partition functions of the process we obtain three different distributions of the average molecular weight, depending on the value of strength of the fragmentation reaction, and prove that a gelation of the process will occur in the thermodynamic limit.

关键词： Keywords Polymer reversible Markov process gelation average molecular weight

Rheological behavior during thermotropic gelation of polyacrylonitrile concentrated solutions

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Journal of Central South University 2008年第S1期15卷 122-125页

作者：马彩霞闫伟霞张莉秦宗益潘鼎 State Key Laboratory for Chemical Fibers Modification and Polymer Materials Donghua University Research Centre for Analysis and Measurement Donghua University

Dynamic viscoelastic properties of polyacrylonitrile(PAN)/DMSO/H2O solutions with different H2O contents were studied as a function of temperature.These PAN solutions gradually became gel with decreasing temperature.The sol-gel transition took place at a critical gel temperature,at which the scaling law of G'(ω)～G″(ω)∝ωn held,allowing an accurate determination of the critical gel temperature by means of the frequency independence of the loss tangent.The gel point of PAN solutions increases with increasing H2O content.The scaling exponent n(=0.86) at the gel point is confirmed to be universal for PAN gels,which is independent of temperature,suggesting the similarity of the fractal structure in the critical PAN gels.

关键词： polyacrylonitrile gel point thermotropic gelation rheological behavior

An analysis of fractal geometry of macromolecular gelation

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Science China Chemistry 1996年第5期39卷 468-476页

作者：左榘陈天红冉少峰何炳林董宝中生文君杨恒林 State Key Laboratory of Functional Polymeric Materials for Adsorption and Separation Department of Chemisry Nankai University Tianjin 300071 China Department of Chemisry Nankai University Tianjin 300071 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039 China

With fractal geometry theory and based on experiments, an analysis of fractal geometry behavior of gelation of macromolecules was carried out. Using the cross-linking copolymerization of styrene-divinylbenzene (DVB) as an example, through the determinations of the evolution of the molecular weight, size and the dependence of scattering intensity on the angle of macromolecules by employing laser and synchrotron small angle X-ray scattering, respectively, this chemical reaction was described quantitatively, its fractal behavior was analyzed and the fractal dimension was also measured. By avoiding the complex theories on gelation, this approach is based on modern physical techniques and theories to perform the analysis of the behavior of fractal geometry of macromolecular gelation and thus is able to reveal the rules of this kind of complicated gelation more essentially and profoundly.

关键词： gelation fractal geometry styrene-divinylbenzene.