Zeitschriftenartikel: „Particle polymerization“

1

Šňupárek, Jaromír, Pavel Bradna, Libuše Mrkvičková, František Lednický und Otakar Quadrat. „Effect of Coagulative Mechanism of Particle Growth on the Structural Heterogeneity of Ethyl Acrylate-Methacrylic Acid Copolymer Latex Particles“. Collection of Czechoslovak Chemical Communications 58, Nr. 10 (1993): 2451–57. http://dx.doi.org/10.1135/cccc19932451.

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Latex particles of ethyl acrylate-methacrylic acid copolymers prepared by semicontinuous emulsion polymerization with a monomer emulsion feed were found to disintegrate into smaller subparticles on alkalization. The phenomenon observed by light scattering and scanning electron microscopy is explained in terms of heterogeneous structure of latex particles which are agglomerates of small particles formed by coagulation during polymerization. The influence of particle size and polymerization route on particle heterogenity is discussed.

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Yogo, Toshinobu, Tomoyuki Nakamura, Ko-ichi Kikuta, Wataru Sakamoto und Shin-ichi Hirano. „Synthesis of α–Fe2O3 particle/oligomer hybrid material“. Journal of Materials Research 11, Nr. 2 (Februar 1996): 475–82. http://dx.doi.org/10.1557/jmr.1996.0057.

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A nanocrystalline α–Fe2O3 particle/oligomer hybrid can be synthesized by polymerization of iron (III) 3-allylacetylacetonate (IAA) followed by in situ hydrolysis. The polymerization of IAA was dependent upon the polymerization temperature and solvent. GPC measurement showed that the polymerization degree of the IAA oligomer ranged from ∼3 to ∼6. The magnetic particle/oligomer hybrid was synthesized by hydrolysis of the IAA oligomer under a neutral or alkaline condition. Crystalline particles from 10 to 40 nm were finely dispersed in the oligomeric matrix, depending upon the hydrolysis conditions. The nanocrystalline particles below 10 nm in diameter were identified to be α−Fe2O3 by electron diffraction. The nanosized α−Fe2O3/oligomer hybrid was found to show superparamagnetic behavior.

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Zhang, Wenyang, Zhengwen Wu, Hanjun Mao, Xinwei Wang, Jianlong Li, Yongyi Mai und Jianyong Yu. „Particle morphology, structure and properties of nascent ultra-high molecular weight polyethylene“. Royal Society Open Science 7, Nr. 8 (August 2020): 200663. http://dx.doi.org/10.1098/rsos.200663.

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The effects of particle morphology on the structure and swelling/dissolution and rheological properties of nascent ultra-high molecular weight polyethylene (UHMWPE) in liquid paraffin (LP) were elaborately explored in this article. Nascent UHMWPE with different particle morphologies was prepared via pre-polymerization technique and direct polymerization. The melting temperature and crystallinity of UHMWPE resins with different particle morphologies were compared, and a schematic diagram was proposed to illustrate the mechanism of UHMWPE particle growth synthesized by pre-polymerization method and direct polymerization. The polymer globules in the nascent UHMWPE prepared by using pre-polymerization technique are densely packed and a positive correlation between the particle size and the viscosity-averaged molecular weight can be observed. The split phenomenon of particles and the fluctuation in the viscosity of UHMWPE/LP system prepared by direct polymerization can be observed at a low heating rate and there is no correlation between particle size and viscosity-averaged molecular weight.

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Yogo, Toshinobu, Tomoko Nakafuku, Wataru Sakamoto und Shin-ichi Hirano. „Synthesis of ZnO particle–polymer hybrid from zinc–organics“. Journal of Materials Research 19, Nr. 2 (Februar 2004): 651–56. http://dx.doi.org/10.1557/jmr.2004.19.2.651.

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Nanocrystalline ZnO particle–polymer hybrid was synthesized by controlled polymerization and hydrolysis of zinc acrylate (ZA). 13C nuclear magnetic resonance spectra revealed the polymerization of ZA during hydrolysis in the presence of hydrazine at 65 °C for 24 h. Nanocrystalline ZnO particles were dispersed in the organic matrix through the polymerization–hydrolysis reaction of ZA using hydrazine or methylhydrazine. ZnO particles increased in crystallinity with increasing amount of water for hydrolysis in the system using hydrazine. Methylhydrazine was found to yield ZnO with higher crystallinity than that obtained using hydrazine. The nanocrystalline particles were identified to be ZnO by electron diffraction. ZnO particle–polymer hybrid was workable by mild heating into transparent films between silica plates. The absorption edge of the transparent ZnO particle–polymer hybrid film was blue-shifted depending on the size of ZnO particles.

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Capek, I. „On the inverse miniemulsion copolymerization and terpolymerization of acrylamide, N, N′-methylenebis(acrylamide) and methacrylic acid“. Open Chemistry 1, Nr. 3 (01.09.2003): 291–304. http://dx.doi.org/10.2478/bf02476230.

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AbstractThe kinetics of free-radical copolymerization and terpolymerization of acrylamide (AAm), N, N′-methylenebis(acrylamide) (MBA) and methacrylic acid (MA) in the inverse water/monomer/cyclohexane/Tween 85 miniemulsion was investigated. Polymerizable sterically-stable miniemulsions were formulated in cyclohexane as a continuous medium. Polymerizations are very fast and reach the final conversion within several minutes. The dependence of the polymerization rate vs. conversion is described by a curve with two nonstationary rate intervals. The maximum rate of polymerization slightly increases with increasing concentration of crosslinking monomer (MBA) and strongly decreases by the addition of MA. The rate of polymerization is inversely proportional to the 0.9th and 1.8th power of the particle concentration without and with MA, respectively. The number of polymer particles is inversely proportional to the 0.18th and 0.13th power of MBA concentration. The kinetic and colloidal parameters of the miniemulsion polymerization are discussed in terms of microemulsion polymerization model.

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Park, Jae-Jung, Yongsoo Kim, Chanmin Lee, Donghyun Kim, Wonjun Choi, Hyukjun Kwon, Jung-Hyun Kim, Ki-Seob Hwang und Jun-Young Lee. „Morphological Analysis of PSMA/PEI Core–Shell Nanoparticles Synthesized by Soap-Free Emulsion Polymerization“. Nanomaterials 11, Nr. 8 (29.07.2021): 1958. http://dx.doi.org/10.3390/nano11081958.

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Emulsion polymerization presents the disadvantage that the physical properties of polymer particles are altered by surfactant adsorption. Therefore, in the soap-free emulsion polymerization method, a hydrophilic initiator is utilized while inducing repulsion among particles on the polymer particle surface, resulting in stable polymer particle production. In this study, we developed a methodology wherein spherical and uniform poly(styrene-co-maleic anhydride) (PSMA)/polyethyleneimine (PEI) core–shell nanoparticles were prepared. Further, their morphology was analyzed. During PSMA polymerization, the addition of up to 30% maleic anhydride (MA) resulted in stable polymerization. In PSMA/PEI nanoparticle fabrication, the number of reactants increased with increased initial monomer feed amounts; consequently, the particle size increased, and as the complete monomer consumption time increased, the particle distribution widened. The styrene (St) copolymer acted as a stabilizer, reducing particle size and narrowing particle distribution. Furthermore, the monomers were more rapidly consumed at high initiator concentrations, irrespective of the initiator used, resulting in increased particle stability and narrowed particle distribution. The shell thickness and particle size were PEI feed ratio dependent, with 0.08 being the optimal PEI-to-MA ratio. The fabricated nanoparticles possess immense potential for application in environmental science and in chemical and health care industries.

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Tiwari, Aishwarya. „Calculations of the Average Number of Radicals per Particle in Emulsion Polymerization“. International Journal for Research in Applied Science and Engineering Technology 9, Nr. VI (15.06.2021): 1056–59. http://dx.doi.org/10.22214/ijraset.2021.35189.

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In emulsion polymerization, the free radicals enter the particles intermittently from the aqueous phase. The number of radicals per particleis given by the Smith-Ewart recursion relation which balances the rate of radical entry into, the rate of radical exit from and the rate of radical termination inside the particle. Models for emulsion polymerisation are based on the 0-1 kinetics or the pseudo-bulk kinetics. Small particles, low initiator concentrations and large number of particles favour the 0–1 kinetics, whereas the large particles, high initiator concentrations and small number of particles will favour pseudo-bulk kinetics. A given polymerization system may exhibit both these kinetic behaviours, initially following the 0-1 kinetics and during the later stages of polymerization following the pseudo-bulk kinetics. The aim of this work is to calculate the time dependent values of the average number of radicals per particle in emulsion polymerization for the pseudo-bulk kinetics.

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Li, Joshua Qing Song, Yan Qiu Wang und Hai Wang. „Preparation and Characterization of Silica/Polymer Hybrid Submicron Particles via a Semi-Continuous Soap-Free Emulsion Polymerization“. Advanced Materials Research 1120-1121 (Juli 2015): 225–32. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.225.

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Submicron hybrid particles were prepared by direct polymerization of three monomers of styrene, methyl methacrylate (MMA), and vinyl acetate (VAC) onto the hydrophilic surface of 230 nm silica submicron particles without any coupling agent in a semi-continuous emulsifier-free emulsion polymerization at a monomer starved condition. The polymerization was initiated by potassium persulfate with constant monomer feed at 0.01, 0.02, or 0.04 mL/min, after adding 230 nm silica seed particles. The particle growth was investigated with a laser particle size analyzer and SEM, and the particle surfaces by Fourier transform infrared spectroscopy (FT-IR). It was founded that the growth of the hybrid particles depended on the hydrophobic characteristics of the polymers. When monomer was the most hydrophobic styrene, polystyrene (PS) shells split off from the hydrophilic surface of the unmodified silica particle whenever the shells reached a limit of ~20 nm. However, both polymethyl methacrylate (PMMA) and polyvinyl acetate (PVAC) shells grew constantly on the hydrophilic surface of silica particles. In the process of the whole reaction, the SiO2/PMMA and SiO2/PVAC hybrid particles kept almost monodisperse.

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Wang, Qiao, Jin Liang Li, Ai Ping Fu und Hong Liang Li. „Effect Factors on the Preparation of Polystyrene Microspheres by Emulsifier-Free Emulsion Polymerization“. Advanced Materials Research 926-930 (Mai 2014): 304–7. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.304.

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Emulsifier-free emulsion polymerization is a technique derived from conventional emulsion polymerization in which polymerization is carried out in the absence of emulsifiers. This technique is useful for the preparation of polymer colloids with narrow particle size distributions and well defined surface properties. Emulsifier-free emulsion polymerization eliminates the disadvantages of conventional emulsion polymerizations stemming from the use of emulsifiers, e.g. impurities in products caused by residual emulsifier and poor water-resistance of films induced by polymer latex.

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CHOI, H. J., M. S. CHO und I. S. LEE. „ELECTRORHEOLOGY OF MONODISPERSE CORE/SHELL STRUCTURED PARTICLE SUSPENSIONS“. International Journal of Modern Physics B 19, Nr. 07n09 (10.04.2005): 1077–82. http://dx.doi.org/10.1142/s0217979205029882.

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As a novel candidate of electrorheological (ER) material, core/shell composite particles (PAPMMA) of poly(methyl methacrylate) (PMMA) core and polyaniline (PANI) shell were prepared and adopted as a dispersed phase. PAPMMA particles, obtained by a dispersion polymerization method, were spherical and possessed a monodisperse particle size distribution, in which the PANI shell was introduced on the surface of PMMA via an in-situ polymerization of aniline by adding an oxidant in an aqueous acidic solution. Yield stress of the PAPMMA suspensions under an applied electric field was observed to be increased with a particle size. In addition, monodisperse acrylic microspheres with aniline moiety on the surface were prepared by a seeded emulsion method, and then composite particles possessing chemically bonded PANI shell (PA-PGMA) were prepared via an in-situ polymerization of aniline. Their ER characteristics were also examined.

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Zhang, Ke Hong, Hui Xiao und Jun Juan Du. „The Effects of the Reaction Conditions on the Grafting Degree of SiO₂-g-PMAA Particle“. Advanced Materials Research 581-582 (Oktober 2012): 301–4. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.301.

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Modified MPS-SiO2 particle was obtained by the bonding of 3-methacryloxypropyl trimethoxysilane (KH-570) on the surface of silica gel particle. The methacrylic acid (MMA) monomers were grafted on the surface of MPS-SiO2 particle to prepare the grafting particles SiO2-g-PMAA. The effects of reaction conditions on the graft degree were explored. The results indicate that the MMA monomers can be easily grafted on the surface of silica gel particle by using the method of graft polymerization. During the graft polymerization, the grafted polymer layer is a hindrance to the subsequent graft polymerization. Then the grafting degree of the polymer under a certain condition has a limiting value. The reaction conditions, such as monomer concentration, the amount of initiator, reaction temperature, have remarkably influence on the graft polymerization of SiO2-g-PMAA.

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Zhang, Ke Hong, Jun Juan Du, Hui Xiao und Yan Yuan. „Preparation and Characterization of PMAA/SiO₂ Composite Particle Via Emulsion Polymerization“. Advanced Materials Research 528 (Juni 2012): 184–87. http://dx.doi.org/10.4028/www.scientific.net/amr.528.184.

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Silica gel particle was chemically modified by using 3-methacryloxypropyl trimethoxysilane (KH-570) as coupling agent. Then poly methyl acrylic acid (PMAA) was grafted on the surface of particles MPS-SiO2 with the method of Emulsion Polymerization, and grafting particles PMMA/SiO2 were prepared. The grafting particle PMAA/SiO2 was characterized by using FT-IR, TG and SEM. The experimental results show that the graft polymerization of methyl acrylic acid (MAA) on onto the surface of silica gel particles can successfully realized using the method of “graft from”. During the graft polymerization, the grafted polymer layer is a hindrance to the subsequent graft polymerization. When the grafted polymer layer reach to a certain density via overlapping and entwisting, a kinetic barrier will be built up. Hence, the grafting degree of the polymer under a certain condition has a limiting value.

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Nestorovic, Gordana, Slobodan Jovanovic und Katarina Jeremic. „The influence of some factors on the electrical conductivity and particle size of core/shell polystyrene/polyaniline composites“. Journal of the Serbian Chemical Society 70, Nr. 11 (2005): 1263–71. http://dx.doi.org/10.2298/jsc0511263n.

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The electrically conductive, micron-sized, core/shell polystyrene (PS)/polyaniline (PANI) composite particles were synthesized by chemical oxidative polymerization of aniline in the presence of micron-sized PS particles in 1 M HCl. The conditions of the dispersion polymerization of styrene were optimized. The influence of the initiator type employed for the chemical oxidative polymerization of aniline and the aniline (ANI) concentration on the PS/PANI particle size and size distribution and their conductivity was investigated. The obtained results show that the conductivity of the samples increased with increasing ANI concentration. The conductivity of the PS/PANI composite particles obtained with the highest ANI concentration was of the same order of magnitude as that for PANI powder. The particle size did not depend on the concentration of ANI, while the particle size distribution was narrower at higher concentrations of ANI. .

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Saade, Hened, Suleidi Torres, Cynthia Barrera, Julieta Sánchez, Yolanda Garza und Raúl G. López. „Effect of pH and Monomer Dosing Rate in the Anionic Polymerization of Ethyl Cyanoacrylate in Semicontinuous Operation“. International Journal of Polymer Science 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/827059.

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Nanoparticles of poly(ethyl cyanoacrylate) with more than 10% solids content were prepared by semicontinuous heterophase polymerization at monomer-starved conditions varying the initial pH in the interval of 1–1.75 and at two monomer dosing rates. Measurements by scanning-transmission electron microscopy allowed us to identify an inverse dependence of particle size on pH. Furthermore, all the polymerizations conducted at the slower monomer dosing rate rendered two particle populations, with the larger one formed from the aggregation of a fraction of the smaller particles. It was believed that the so slow addition of the monomer caused the formation of very small but instable particles, thereby a fraction of which aggregated to reduce the total interface particles-aqueous phase, increasing the latex stability. An increase in the monomer dosing rate led to larger and more stable particles in such way that only one population of nanoparticles with around 40 nm in average diameter was obtained.

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Duan, Yu Feng, und Zhao Xia Fu. „Preparation and Characterization of Magnetic Toner Particles by Direct Polymerization Method“. Advanced Materials Research 217-218 (März 2011): 1702–7. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.1702.

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In this study a kind of black toner, containing polymer, magnetic iron oxide pigment, and several other additives, was prepared by a suspension polymerization method. The morphology, influence factor of particle size, and glass transition of prepared toner were discussed. SEM image showed that the produced micron-sized particles have a spherical surface and the various chemicals were mixed into monomers during manufacturing of the particles. Discussion about particle formation and stability concluded that the toner particle size related with stabilizer concentration, stirrer speed, and crosslinking agent concentration. The bigger particles, resulted from droplets coalescence during polymerization process, disappeared when enough PVA stabilizer was used in the aqueous medium. .Increasing the stirrer speed corresponded to the decrease of the particles size. But any increase in stirrer speed t did not contribute to size reduction in small particles below 2μm. It was found that particle size decrease with the addition of crosslinking agent. The DSC result indicated the glass transition of polymerized toner could be effectively adjusted according to Fox equation through change the monomer ratio.

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Song, Zhigiang, und Gary W. Poehlein. „Particle Formation in Emulsion Polymerization: Transient Particle Concentration“. Journal of Macromolecular Science: Part A - Chemistry 25, Nr. 4 (Januar 1988): 403–43. http://dx.doi.org/10.1080/00222338808053377.

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Li, Ming Jue, Ying Yan Diao und Xi Jun Liu. „Synthesis and Characterization of PBA/aPS Core-Shell Latex Particles“. Advanced Materials Research 631-632 (Januar 2013): 588–91. http://dx.doi.org/10.4028/www.scientific.net/amr.631-632.588.

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The core-shell structure copolymer of PBA/PS was prepared using pre-emulsion and semi-continues polymerization process. The particle size of core-shell latex and the St conversion of shell monomer were affected by emulsifier, initiator, pH and temperature etc. Meanwhile, the laser particle size analyzer, transmission electron microscope and other test methods were utilized to study latex particle average particle size, size distribution and morphological structure, respectively. The kinetics of polymerization was investigated. Well-defined core-shell structure and narrow particle sizedistribution could be achieved under starved conditions of monomer feeding. By the means of TEM found that PBA/PS latex particles had clearly core/shell morphology.

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Dong, Jie, Xiang'an Yue und Jie He. „Template Polymerization of Acrylamide in Ethanol/Water Mixtures“. Australian Journal of Chemistry 69, Nr. 10 (2016): 1149. http://dx.doi.org/10.1071/ch16189.

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Irregular hollow polyacrylamide (PAAm) particles with the mean diameter varying from 125 to 413 nm were prepared in ethanol/water mixtures by template polymerization using polyvinyl butyral (PVB) microspheres as the template and 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The influence of the solvent composition, monomer concentration, and template concentration on the yield, molecular weight, and particle size of PAAm were investigated. Decreasing the volume ratio of ethanol to water or increasing the monomer concentration can increase the yield, molecular weight, and particle size of PAAm. The monomer concentration threshold for coagulum-free polymerization is 6 % (w/v). Although the PVB concentration does not show significant influence on the yield, molecular weight, and particle size of PAAm, keeping the PVB concentration between 0.1 and 0.3 % (w/v) is the key to forming PVB microspheres. The formation of PAAm particles is discussed based on transmission electron microscopy results, it is concluded that the shrinkage and dehydration on hollow PAAm particles, which is caused by the removal of templates, results in the formation of micro-sized irregular hollow PAAm particles.

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Lok, Kar P., und Christopher K. Ober. „Particle size control in dispersion polymerization of polystyrene“. Canadian Journal of Chemistry 63, Nr. 1 (01.01.1985): 209–16. http://dx.doi.org/10.1139/v85-033.

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In a dispersion polymerization process, the reaction mixture starts out as a homogeneous solution and the resulting polymer precipitates as spherical particles, stabilized by a steric barrier of dissolved polymer. The final polymer particle size is determined by the inherent polymer aggregation behaviour under a given set of conditions. In the present study styrene polymerization was studied in various solvents using cellulosic derivatives as the steric stabilizer. Some of these solvents in certain combinations allowed the direct preparation of particles in the micron size and their size distribution appeared to be highly dependent on the monomer–solvent–initiator system. Investigations of these factors have suggested that monodisperse particles up to 12 μm can be prepared in a single step; studies of several systems are delineated.

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de Arbina, Lourdes López, María J. Barandiaran, Luis M. Gugliotta und JoséM Asuat. „Emulsion polymerization: particle growth kinetics“. Polymer 37, Nr. 26 (Januar 1996): 5907–16. http://dx.doi.org/10.1016/s0032-3861(96)00444-2.

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Li, Hua-Rong, Liming Che und Zheng-Hong Luo. „Modeling intraparticle transports during propylene polymerizations using supported metallocene and dual function metallocene as catalysts: Single particle model“. Chemical Industry and Chemical Engineering Quarterly 20, Nr. 2 (2014): 249–60. http://dx.doi.org/10.2298/ciceq120722006l.

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Two improved multigrain models (MGMs) for preparing homopolypropylene and long chain branched polypropylene via propylene polymerization using silica-supported metallocene or dual function metallocene as catalysts are presented in this paper. The presented models are used to predict the intraparticle flow fields involved in the polymerizations. The simulation results show that the flow field distributions involve dare basically identical. The results also show that both the two polymerization processes have an initiation stage and the controlling step for them is reaction-diffusion-reaction with the polymerization proceeding. Furthermore, the simulation results show that the intra particle mass transfer resistance has significant effect on the polymerization but the heat transfer resistance can be ignored.

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Leary, B., und CJ Lyons. „A Novel Composite Polymer Latex Technology“. Australian Journal of Chemistry 42, Nr. 12 (1989): 2055. http://dx.doi.org/10.1071/ch9892055.

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The physical chemistry involved in the invention and development of a novel aqueous composite polymer latex technology at Dulux Australia is described. The polymerization process employed leads to a latex wherein each particle contains a blend of two or more copolymers. These particles are sterically stabilized by a new class of non-ionic reactive surfactant which results in excellent colloidal stability. A paint based on this technology has been commercialized in the coil coating industry. The particle size distribution of the latex used in this paint is studied before, during and after polymerization. The evidence obtained confirms that the desired composite polymer particles are formed by a suspension polymerization mechanism and that little or no polymer separation due to secondary nucleation (nucleation of polymer particles from the aqueous phase) takes place.

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Jamari, Siti Khumaira Mohd, Nur Azmah Nordin, Ubaidillah, Siti Aishah Abdul Aziz, Nurhazimah Nazmi und Saiful Amri Mazlan. „Systematic Review on the Effects, Roles and Methods of Magnetic Particle Coatings in Magnetorheological Materials“. Materials 13, Nr. 23 (24.11.2020): 5317. http://dx.doi.org/10.3390/ma13235317.

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Magnetorheological (MR) material is a type of magneto-sensitive smart materials which consists of magnetizable particles dispersed in a carrier medium. Throughout the years, coating on the surface of the magnetic particles has been developed by researchers to enhance the performance of MR materials, which include the improvement of sedimentation stability, enhancement of the interaction between the particles and matrix mediums, and improving rheological properties as well as providing extra protection against oxidative environments. There are a few coating methods that have been employed to graft the coating layer on the surface of the magnetic particles, such as atomic transfer radical polymerization (ATRP), chemical oxidative polymerization, and dispersion polymerization. This paper investigates the role of particle coating in MR materials with the effects gained from grafting the magnetic particles. This paper also discusses the coating methods employed in some of the works that have been established by researchers in the particle coating of MR materials.

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Zhao, Zong Qian, Bu Qin Xu, Gui Long Xu, Yi Wang und Jian Hu. „Preparation and Characterization of Soap-Free Cationic Polystyrene Microspheres Using a Water Soluble Monomer“. Advanced Materials Research 988 (Juli 2014): 84–88. http://dx.doi.org/10.4028/www.scientific.net/amr.988.84.

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Soap-free Cationic polystyrene microspheres were prepared by emulsion polymerization using a water soluble monomer Methacrylatoethyl trimethyl ammonium chloride (MADAC). Experimental studies were performed in detail to check the effect of the synthesis process of the microspheres, the MADAC dosage, and initiator dosage on the particle size and distribution. The chemical structure of latex particles was characterized by Fourier transform infrared spectroscopy. The micro-morphology of latex particles were observed by Transmission electron microscope. The results show that different particle sizes of polystyrene microspheres with good monodispersity were finally obtained by seeded semi-continuous emulsion polymerization.

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Wang, Gu Qin, und Yang Cui. „Preparation of PVAc/CNT/Carbon Black Composite Particles“. Applied Mechanics and Materials 457-458 (Oktober 2013): 262–65. http://dx.doi.org/10.4028/www.scientific.net/amm.457-458.262.

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Conductive PVAc/CNT/CB composite particles were prepared through emulsion polymerization. To get the good dispersity and chemical reactivity in the polymerization system, CNT was first modified with high concentrated nitric acid and sulfuric acid. And then in the polymerization process CNT and CB were evenly dispersed into the poly (vinyl acetate) matrix and a uniform and stable conductive network was obtained finally. A series of composite particle were prepared by changing the content of CNT. And the resistivity and structure of composite particles were determined by four-probe method and FTIR. Furthermore, the kinetics of emulsion polymerization was also investigated.

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Li, Joshua Qing Song, Hai Wang und Yan Qiu Wang. „Preparation of Silica/Polymer Hybrid Nanoparticles via a Semi-Continuous Soup-Free Emulsion Polymerization“. Advanced Materials Research 1120-1121 (Juli 2015): 233–42. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.233.

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Hybrid nanoparticles were prepared by direct polymerization of methyl methacrylate, vinyl acetate, and styrene monomers onto the unmodified hydrophilic surfaces of 33 nm silica nanoparticles in a semi-continuous soap-free emulsion polymerization at a monomer starved condition. The polymerization was initiated by potassium persulfate with constant monomer feed at 0.01, 0.02, or 0.04 mL/min. The growth of the core-shell nanoparticles were measured by a laser particle size analyzer. FT-IR spectra analysis confirmed the hybrid structures of the synthesized nanoparticles. SEM images and size exclusion chromatography (SEC) results indicated regular core-shell microsphere structures. The hybrid nanoparticles increased in monodispersity and size over 100 nm with the reaction. However, SiO2/polystyrene (PS) nanoparticles grew much faster compared with SiO2/polymethyl methacrylate (PMMA) and SiO2/polyvinyl acetate (PVAC). There was particle coagulation, about 12 SiO2/PS particles aggregating to one, in the early stage of the seeded process. In addition, PS secondary particles were formed before the particle coagulation, and then merged with the SiO2/PS nanoparticles in the particle coagulation. The formation of SiO2/polymer hybrid nanoparticles depended on the hydrophilic characteristics of the polymer, and the size of silica seeds.

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Gu, Wen Juan, Xiao Hui Zhang und Jie Li. „Preparation of PVAc Particles by Dispersion Polymerization“. Applied Mechanics and Materials 184-185 (Juni 2012): 1134–37. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.1134.

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Highly uniform polyvinylacetate particles of submicron size were prepared by dispersion polymerization in mixed media of isopropanol and water initiated by redox initiator of NaHSO3 and K2S2O8 using poly(N-vinylpyrrolidone) as stabilizer. Monomer conversion was studied gravimetrically. Both the morphology and the size of the particles were measured by TEM. The influences of various polymerization parameters, such as monomer concentration, stabilizer content, on the particle properties were systematically investigated. The PVAc particles synthesized in this research were mono-disperse spheres with the diameter between 100-1000 nm.

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Wang, Xiaodong, Kai Chen, Ting Kang und Jie Ouyang. „A Dynamic Coarse Grain Discrete Element Method for Gas-Solid Fluidized Beds by Considering Particle-Group Crushing and Polymerization“. Applied Sciences 10, Nr. 6 (12.03.2020): 1943. http://dx.doi.org/10.3390/app10061943.

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The discrete element method (DEM) coupled with computational fluid dynamics (CFD) is used extensively for the numerical simulation of gas-solid fluidized beds. In order to improve the efficiency of this approach, a coarse grain model of the DEM was proposed in the literature. In this model, a group of original particles are treated as a large-sized particle based on the initial particle distribution, and during the whole simulation process the number and components of these particle-groups remain unchanged. However, collisions between particles can lead to frequent crushing and polymerization of particle-groups. This fact has typically been ignored, so the purpose of this paper is to rationalize the coarse grain DEM-CFD model by considering the dynamic particle-group crushing and polymerization. In particular, the effective size of each particle-group is measured by a quantity called equivalent particle-group diameter, whose definition references the equivalent cluster diameter used by the energy-minimization multi-scale (EMMS) model. Then a particle-group crushing criterion is presented based on the mismatch between the equivalent diameter and actual diameter of a particle-group. As to the polymerization of two colliding particle-groups, their velocity difference after collision is chosen as a criterion. Moreover, considering the flow heterogeneity induced by the particle cluster formation, the EMMS drag force model is adopted in this work. Simulations are carried out by using a finite volume method (FVM) with non-staggered grids. For decoupling the Navier-Stokes equations, the semi-implicit method for pressure linked equations revised (SIMPLER) algorithm is used. The simulation results show that the proposed dynamic coarse grain DEM-CFD method has better performance than the original one.

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29

Brokken-Zijp, J. C. M., O. L. J. van Asselen, W. E. Kleinjan, R. van de Belt und G. de With. „Photocatalytic Properties of Tin Oxide and Antimony-Doped Tin Oxide Nanoparticles“. Journal of Nanotechnology 2011 (2011): 1–15. http://dx.doi.org/10.1155/2011/106254.

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For the first time it is shown that N-doped SnO2nanoparticles photocatalyze directly the polymerization of the C=C bonds of (meth)acrylates under visible light illumination. These radical polymerizations also occur when these particles are doped with Sb and when the surfaces of these particles are grafted with methacrylate (MPS) groups. During irradiation with visible or UV light the position and/or intensity of the plasmon band absorption of these nanoparticles are always changed, suggesting that the polymerization starts by the transfer of an electron from the conduction band of the particle to the (meth)acrylate C=C bond. By using illumination wavelengths with a very narrow band width we determined the influence of the incident wavelength of light, the Sb- and N-doping, and the methacrylate (MPS) surface grafting on the quantum efficiencies for the initiating radical formation (Φ) and on the polymer and particle network formation. The results are explained by describing the effects of Sb-doping, N-doping, and/or methacrylate surface grafting on the band gaps, energy level distributions, and surface group reactivities of these nanoparticles. N-doped (MPS grafted) SnO2(Sb ≥ 0%) nanoparticles are new attractive photocatalysts under visible as well as UV illumination.

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30

Dunn, Alexander S. „Latex particle nucleation in emulsion polymerization“. European Polymer Journal 25, Nr. 7-8 (Januar 1989): 691–94. http://dx.doi.org/10.1016/0014-3057(89)90030-x.

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31

Elbing, E., AG Parts, CJ Lyons, BAW Coller und IR Wilson. „Miniemulsions of Vinyl Stearate. II. Light-Scattering Studies During the Polymerization“. Australian Journal of Chemistry 42, Nr. 12 (1989): 2085. http://dx.doi.org/10.1071/ch9892085.

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The course of the polymerization of vinyl stearate has been followed by dilatometry and by light scattering. Kinetically stable and visually clear or at most opalescent 'miniemulsions' were used to minimize the scattering (otherwise large) by emulsion droplets. Light-scattering results demonstrate that the final particle size of the latexes may be greater or less than that of the emulsion droplets in the starting miniemulsion. This suggests that polymer particles are nucleated from the aqueous (micelle-containing) phase, and grow by transport of vinyl stearate monomer through the aqueous medium from the emulsion droplets to feed polymerization in the particles. Thus the droplets gradually decrease in size and disappear when all the monomer has been taken up by absorption into micelles or into growing particles. A previously proposed droplet-particle collision theory does not appear to be necessary.

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32

Song, Z., und G. W. Poehlein. „Particle Formation in Emulsion Polymerization: Particle Number at Steady State“. Journal of Macromolecular Science: Part A - Chemistry 25, Nr. 12 (Januar 1988): 1587–632. http://dx.doi.org/10.1080/10601328808055090.

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33

Suzuki, Kazuya, Takeshi Yumura, Yuko Tanaka und Mitsuru Akashi. „pH-Responsive Model Drug Release from Silica-Poly(methacrylic acid) Interpenetrating Gel Hybrids“. Journal of Bioactive and Compatible Polymers 16, Nr. 5 (September 2001): 409–18. http://dx.doi.org/10.1106/1h3c-hn3r-ykua-2b29.

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Stimuli-responsive gel was hybridized with porous silica particles, by radical polymerization of methacrylic acid (MA) in the presence of a crosslinker. Brilliant Blue FCF (BBFCF) was encapsulated in the core of the particle and its release behavior from the particle under specific stimuli was studied. PMA gel hybridized silica particles showed specific release behavior at different pH values while normal silica particles released BBFCF at the same rate at all pHs.

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34

Yogo, Toshinobu, Tomoyuki Nakamura, Wataru Sakamoto und Shin-ichi Hirano. „Synthesis of magnetic particle/organic hybrid from metalorganic compounds“. Journal of Materials Research 14, Nr. 7 (Juli 1999): 2855–60. http://dx.doi.org/10.1557/jmr.1999.0381.

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A nanocrystalline magnetic particle/oligomer hybrid was successfully synthesized by polymerization of iron(III) 3-allylacetylacetonate (IAA) followed by in situ hydrolysis. An iron oxide particle/oligomer hybrid was synthesized by hydrolysis of the IAA oligomer under alkaline and reducing conditions by the addition of hydrazine or methylhydrazine. Crystalline particles of approximately 10 nm were found to be dispersed in the oligomeric matrix. The nanocrystalline particles were identified to be iron oxide spinel by x-ray diffraction analysis and electron diffraction. The nanometer-sized ferrimagnetic iron oxide particle/oligomer hybrid showed a typical superparamagnetic behavior.

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35

Huang, Xianguang, Li Wang und Wantai Yang. „Preparation of core–shell particles by surface-initiated cycloketyl radical mediated living polymerization“. Polymer Chemistry 6, Nr. 37 (2015): 6664–70. http://dx.doi.org/10.1039/c5py00703h.

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Core–shell particles were prepared by surface-initiated cycloketyl radical mediated living polymerization, achieving deliberate control over the particle size and uniformity. It has significant potential for industrial application.

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36

Wang, Xiaoyue, Yueyan Liu, Taiquan Wu und Mingzhou Yu. „Polymerization and Collision in High Concentrations for Brownian Coagulation“. Applied Sciences 11, Nr. 15 (24.07.2021): 6815. http://dx.doi.org/10.3390/app11156815.

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Aggregation always occurs in industrial processes with fractal-like particles, especially in dense systems (the volume fraction, ϕ>1%). However, the classic aggregation theory, established by Smoluchowski in 1917, cannot sufficiently simulate the particle dynamics in dense systems, particularly those of generat ed fractal-like particles. In this article, the Langevin dynamic was applied to study the collision rate of aggregations as well as the structure of aggregates affected by different volume fractions. It is shown that the collision rate of highly concentrated particles is progressively higher than that of a dilute concentration, and the SPSD (self-preserving size distribution) is approached (σg,n≥1.5). With the increase in volume fraction, ϕ, the SPSD broadens, and the geometric standard is 1.54, 1.98, and 2.73 at ϕ=0.1, 0.2, and 0.3. When the volume fraction, ϕ, is higher, the radius of gyration is smaller with the same cluster size (number-based), which means the particle agglomerations are in a tighter coagulation. The fractal-like property Df is in the range of 1.60–2.0 in a high-concentration system. Knowing the details of the collision progress in a high-concentration system can be useful for calculating the dynamics of coagulating fractal-like particles in the industrial process.

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Yogo, Toshinobu, Tomoe Yamamoto, Wataru Sakamoto und Shin-ichi Hirano. „In situ synthesis of nanocrystalline BaTiO3 particle–polymer hybrid“. Journal of Materials Research 19, Nr. 11 (01.11.2004): 3290–97. http://dx.doi.org/10.1557/jmr.2004.0418.

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Nanocrystalline BaTiO3 particle–polymer hybrid was synthesized by polymerization and hydrolysis of [2-(methacryloxy)ethoxy]triisopropoxytitanium (MEPT) and barium alkoxide. The precursor for hybrid was synthesized from prepolymerized MEPT and barium alkokide, which was then hydrolyzed to form BaTiO3 particle–polymer hybrids below 100 °C. BaTiO3 particles increased in crystallinity when the amount of water for hydrolysis increased. The nanocrystalline particles were identified to be BaTiO3 by electron diffraction. Nanometer-sized BaTiO3 particle–polymer hybrid was shaped to a film with a dielectric constant of 8.2 at 10 kHz. A suspension consisting of the hybrid and silicone oil responded to a direct-current field, exhibiting a typical electrorheological behavior.

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38

Elbing, Enn, Simon McCarthy, Susan Snowdon, Bruce A. W. Coller und Ivan R. Wilson. „Aqueous latex polymerization of acrylonitrile. Kinetics, particle numbers and particle sizes“. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 82, Nr. 3 (1986): 943. http://dx.doi.org/10.1039/f19868200943.

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39

Gonçalves, Odinei Hess, Ricardo A. F. Machado, Pedro Henrique Hermes de Araújo und José M. Asua. „Secondary particle formation in seeded suspension polymerization“. Polymer 50, Nr. 2 (Januar 2009): 375–81. http://dx.doi.org/10.1016/j.polymer.2008.11.006.

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40

Sood, Ashwini. „Particle size distribution control in emulsion polymerization“. Journal of Applied Polymer Science 92, Nr. 5 (2004): 2884–902. http://dx.doi.org/10.1002/app.20231.

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41

Okubo, Masayoshi. „Control of particle morphology in emulsion polymerization“. Makromolekulare Chemie. Macromolecular Symposia 35-36, Nr. 1 (Mai 1990): 307–25. http://dx.doi.org/10.1002/masy.19900350119.

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42

Rodríguez, Raquel, María J. Barandiaran und José M. Asua. „Particle Nucleation in High Solids Miniemulsion Polymerization“. Macromolecules 40, Nr. 16 (August 2007): 5735–42. http://dx.doi.org/10.1021/ma070525c.

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43

Lin, M., F. Chu, E. Bourgeat‐Lami und A. Guyot. „Particle Size in Emmulsion Polymerization of Octamethyltetrasiloxane“. Journal of Dispersion Science and Technology 25, Nr. 6 (Januar 2005): 827–35. http://dx.doi.org/10.1081/dis-200035676.

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Landfester, Katharina, F. Joseph Schork und Victor A. Kusuma. „Particle size distribution in mini-emulsion polymerization“. Comptes Rendus Chimie 6, Nr. 11-12 (November 2003): 1337–42. http://dx.doi.org/10.1016/j.crci.2003.07.019.

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45

Tsavalas, John G., F. Joseph Schork und Katharina Landfester. „Particle morphology development in hybrid miniemulsion polymerization“. Journal of Coatings Technology and Research 1, Nr. 1 (Januar 2004): 53–63. http://dx.doi.org/10.1007/s11998-004-0025-z.

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46

Choo, Hun Seung, und Ki Chang Lee. „Preparation of Poly[Styrene(ST)-co-Allyloxy-2-Hydroxypropane Sulfonic Acid Sodium Salt(COPS-I)] Colloidal Crystalline Photonic Crystals“. Journal of Nanoscience and Nanotechnology 15, Nr. 10 (01.10.2015): 7685–92. http://dx.doi.org/10.1166/jnn.2015.11173.

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Colloidal crystalline photonic crystals using highly monodisperse poly[Styrene(ST)-co-Allyloxy-2- hydroxypropane sulfonic acid sodium salt(COPS-I)] microspheres were prepared to study their optical properties under visible light. For this purpose, a series of surfactant-free emulsion copolymerizations was carried out at various reaction conditions such as the changes of ST/COPS-I ratio, polymerization temperature, KPS initiator and DVB crosslinker concentration. All the latices showed highly uniform spherical particles in the size range of 165∼550 nm and the respective opaline structural colors from their colloidal photonic crystals. It is found that the changes in such polymerization factors greatly affect the number of particles and particle diameter, polymerization rate, molecular weight, zeta-potential, and refractive indices.

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Kim, Taeyoon, Joo-Hyun Song, Jong-Ho Back, Bongkuk Seo, Choong-Sun Lim, Hyun-Jong Paik und Wonjoo Lee. „Flame Retardant Submicron Particles via Surfactant-Free RAFT Emulsion Polymerization of Styrene Derivatives Containing Phosphorous“. Polymers 12, Nr. 6 (29.05.2020): 1244. http://dx.doi.org/10.3390/polym12061244.

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The reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of diethyl-(4-vinylbenzyl) phosphate (DEVBP) was performed using PEG-TTC as a macro RAFT agent. PEG-TTC (MW 2000, 4000) was synthesized by the esterification of poly (ethylene glycol) methyl ether with a carboxylic-terminated RAFT agent, composed a hydrophilic poly (ethylene glycol) (PEG) block and a hydrophobic dodecyl chain. The RAFT emulsion polymerization of DEVBP was well–controlled with a narrow molecular size distribution. Dynamic light scattering and confocal laser scanning microscopy were used to examine the PEG-b-PDVBP submicron particles, and the length of the PEG chain (hydrophilic block) was found to affect the particle size distribution and molecular weight distribution. The submicron particle size increased with increasing degree of polymerization (35, 65, and 130), and precipitation was observed at a high degree of polymerization (DP) using low molecular weight PEG-TTC (DP 130, A3). The flame retardant properties of the PEG-b-PDVBP were evaluated by thermogravimetric analysis (TGA) and micro cone calorimeter (MCC). In the combustion process, the residue of PEG-b-PDEVBP were above 500 °C was observed (A1 ~ B3, 27 ~ 38%), and flame retardant effect of PEG-b-PDEVBP submicron particles/PVA composite were confirmed by increasing range of temperature and decreasing total heat release with increasing contents of PEG-b-PDEVBP. The PEG-b-PDEVBP submicron particles can provide flame retardant properties to aqueous, dispersion and emulsion formed organic/polymer products.

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Sarker, P., J. R. Ebdon, S. Rimmer, M. A. J. Miah und H. Ahmad. „Synthesis Kinetics of Polymer / Copolymer Latexes via Radical Ring-Opening Emulsion Polymerization of Vinylcyclopropane“. Journal of Scientific Research 8, Nr. 3 (01.09.2016): 463–72. http://dx.doi.org/10.3329/jsr.v8i3.28183.

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Radical emulsion polymerization of 1,1-bis(ethoxycarbonyl)-2-vinylcyclopropane (ECVCP) was examined in the presence of potassium persulfate (KPS) as an initiator. ECVCP underwent both emulsifier-in emulsion and emulsifier-free emulsion polymerizations to afford the ring-opened polymer in good yields. The copolymerization efficiency of this monomer was also evaluated with methyl methacrylate (MMA) and butyl methacrylate (BMA) as comonomers under the same reaction conditions. The emulsion copolymerization of ECVCP with a relatively hydrophobic monomer, lauryl methacrylate (LMA) was also investigated in presence of ?-cyclodextrin hydrate (?-CD) as a phase transfer agent. Polymerization/copolymerization kinetics, change in particle size and olefin contents were followed during the reaction.

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Lu, Hua Sheng, Zhong Xiao Li, Yu Guang Feng und Jia Ling Pu. „Preparation and Properties of Anionic Polymer Emulsion in the Presence of a Reactive Surfactant“. Applied Mechanics and Materials 262 (Dezember 2012): 430–34. http://dx.doi.org/10.4028/www.scientific.net/amm.262.430.

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Stable polymer emulsion derived from Butyl Methacrylate (BMA), 4-vinyl pyridine (4-VP), vinylidene chloride (VDC) and divinylbenzene (DVB) with different size and distribution were prepared through soapless emulsion polymerization by using a reactive surfactant and a redox initiator. The influences of the quality ratio of the reactive surfactant to the monomers and the dosages of the cross-linking agent on the stability and thermal properties of the emulsion were studied. The obtained polymer nano-particles have higher ξ potential, and the particle sizes have narrow distribution. This polymerization system can give some further understanding on the mechanism of emulsion polymerization .The solid content of the emulsion could be as high as 40% and the particle sizes could be adjusted in the range of 40-300nm. Otherwise, using infrared spectroscopy, size and ξ analyzer, gravitational thermal analysis and differential scanning calorimeter, properties of the emulsion latex were tested. This kind of latex may have applications in the development of water-developable thermal-sensitive material system.

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Wu, Yansong, Jian Li, Wei Ding und Tao Jiang. „Preparation of MgCl2-Supported Ziegler-Natta Catalysts via New Surfactants Emulsion for Propylene Polymerization“. Catalysts 11, Nr. 5 (06.05.2021): 601. http://dx.doi.org/10.3390/catal11050601.

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This article describes a MgCl2-supported Ziegler-Natta catalyst for propylene polymerization prepared via an in situ emulsion technique with new surfactants. The effect of preparation conditions such as the TiCl4/toluene molar ratio, TiCl4-contacting temperature, amount of phthaloyl dichloride, stirring rate, mixing time of TiCl4/toluene with the Mg complex, and the n-butyl chloride loading was investigated in detail. Scanning electron microscopy and laser particle size analyzer measurements showed that the catalyst particles exhibit a perfectly spherical shape, narrow particle size distribution, and low fine powder content. Energy-dispersive X-ray spectrometry indicated that the Ti, Mg, and Cl elements were evenly distributed throughout the particles. Powder X-ray diffraction measurements indicated the presence of δ-MgCl2 in the catalyst, and FTIR and GC-MS studies confirmed the presence of in situ formed di(ethylhexyl)phthalate (DEHP). Bulk polymerization of propylene using the catalyst was studied, and it was found that the catalyst displayed high activity, high bulk density with high stereospecificity, and excellent hydrogen sensitivity. The polymer produced by the catalyst has a narrow particle size distribution with a low fine powder content.

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