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Synthesis and Characterization of the in Situ Bulk Polymerization of PMMA Containing Graphene Sheets Using Microwave Irradiation  [PDF]
Mohammad A. Aldosari,Ali A. Othman,Edreese H. Alsharaeh
Molecules , 2013, DOI: 10.3390/molecules18033152
Abstract: Polymethylmethacrylate–graphene (PMMA/RGO) nanocomposites were prepared via in situ bulk polymerization using two different preparation techniques. In the first approach, a mixture of graphite oxide (GO) and methylmethacrylate monomers (MMA) were polymerized using a bulk polymerization method with a free radical initiator. After the addition of the reducing agent hydrazine hydrate (HH), the product was reduced via microwave irradiation (MWI) to obtain R-(GO-PMMA) composites. In the second approach, a mixture of graphite sheets (RGO) and MMA monomers were polymerized using a bulk polymerization method with a free radical initiator to obtain RGO-(PMMA) composites. The composites were characterized by FTIR, 1H-NMR and Raman spectroscopy and XRD, SEM, TEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability compared with the composites prepared without MWI.
E-Beam Graft Polymerization of Hydrophilic PEG-Methacrylate on the Surface of PMMA  [PDF]
Seong-Cheol Kim, PilHo Huh
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2012, DOI: 10.4236/jsemat.2012.24040
Abstract: The graft polymerization of hydrophilic monomers on the surface of hydrophobic PMMA was performed using an electron beam (e-beam). The dose of e-beam irradiation, reaction concentration, temperature, and reaction time were used to study the effect of variables on the graft density of poly (ethylene glycol)-methacrylate. The results demonstrated that the weight percentage of graft polymer increased with increasing temperature, time and monomer concentration. However, the weight of the graft polymer did not increase with the increasing dose of e-beam irradiation. The change of the contact angle of the water droplet on the PMMA surface was monitored as a function of a reaction time. The results showed that the contact angle decreased up until a specific time and then leveled off to an approximately constant value after a certain reaction time of the graft polymerization. Transmission electron microscopy proved that the constant value of the contact angle was due to the local survival of surface radicals followed by the perpendicular diffusion of monomers only into the bulk of the surface-modified area on the sheet surface.
Investigation on the Preparation of μ-sized PMMA Microspheres by the Dispersion Polymerization
分散聚合法制备微米级PMMA微球的研究

WU Shao-Gui,LIU Bai-Ling,
伍绍贵
,刘白玲

中国科学院研究生院学报 , 2006,
Abstract: The micron-grade PMMA microspheres with narrow size distribution were prepared by dispersion polymerization.The mechanism of the dispersion polymerization was discussed.The factors influencing both the size and the size distribution of the microspheres including initial concentrations of the initiator,the monomer,the stabilizer,the polarity of the medium and the reaction conditions were studied.The results indicated that the size and the size distribution of microspheres both increased with initial concentrations of the initiator and the monomer.Increasing the amount of the stabilizer decreased the size and narrowed the size distribution of microspheres.Other factors such as the polarity of the medium and the reaction temperature had great influences too.By controlling these factors,the desired-size monodisperse microspheres could be obtained.
Comparison of techniques for the determination of conversion during suspension polymerization reactions
Santos, J. C.;Lopes, C. N.;Reis, M. M.;Giudici, R.;Sayer, C.;Machado, R. A. F.;Araújo, P. H. H.;
Brazilian Journal of Chemical Engineering , 2008, DOI: 10.1590/S0104-66322008000200017
Abstract: the determination of conversion during suspension polymerization reactions is not an easy task due to the heterogeneity of the reaction medium and the tendency of particles to agglomerate rapidly when stirring is stopped. usually, bulk polymerization in ampoules is employed to study the kinetics of suspension polymerization reactions. in this work, a comparison of different techniques for the determination of conversion during suspension polymerization reactions is presented. results showed a good agreement between the conversion obtained by gravimetry during styrene suspension polymerization and on-line conversion monitoring data using fiber-optic based raman spectroscopy. nevertheless, the polymerization rate of styrene bulk polymerization carried out in ampoules was higher than the real reaction rate of styrene suspension polymerization due to slightly higher reaction temperatures. simulation results using the experimental temperature data in a mathematical model confirmed these results.
Mathematical modeling of polystyrene particle size distribution produced by suspension polymerization
Machado, R.A.F.;Pinto, J.C.;Araújo, P.H.H.;Bolzan, A.;
Brazilian Journal of Chemical Engineering , 2000, DOI: 10.1590/S0104-66322000000400004
Abstract: particle size distribution (psd) of polystyrene particles produced by suspension polymerization is of fundamental importance in determining suspension stability and product quality attributes. within a population balance framework, a model is proposed for suspension polymerization reactors to describe the evolution of the psd. the model includes description of breakage and coalescence rates in terms of reaction kinetics and rheology of the dispersed phase. the model is validated with experimental data of styrene suspension polymerization.
Mathematical modeling of polystyrene particle size distribution produced by suspension polymerization  [cached]
Machado R.A.F.,Pinto J.C.,Araújo P.H.H.,Bolzan A.
Brazilian Journal of Chemical Engineering , 2000,
Abstract: Particle size distribution (PSD) of polystyrene particles produced by suspension polymerization is of fundamental importance in determining suspension stability and product quality attributes. Within a population balance framework, a model is proposed for suspension polymerization reactors to describe the evolution of the PSD. The model includes description of breakage and coalescence rates in terms of reaction kinetics and rheology of the dispersed phase. The model is validated with experimental data of styrene suspension polymerization.
Presence of Two Maxima in the Isothermal Free-Radical Polymerization Rate of Isobornyl Methacrylate Retarded by Oxygen  [PDF]
Ezequiel R. Soule,Julio Borrajo,Roberto J. J. Williams
Physics , 2013, DOI: 10.1021/ma0350314
Abstract: The kinetics of the free-radical polymerization of isobornyl methacrylate (IBoMA) at 80C, initiated by benzoyl peroxide (BPO), was determined by differential scanning calorimetry (DSC), using sample pans previously sealed in air or in nitrogen. The polymerization was arrested by vitrification at a final conversion close to 0.80. The kinetics in nitrogen could be fitted using initiation and propagation rate constants reported in the literature, a functionality of the termination rate constant controlled by translational diffusion based on the free-volume model, and an efficiency factor for the initiator decomposition that decreased with conversion in the medium-high conversion range. The presence of oxygen led to a significant decrease in the polymerization rate, an effect that was enhanced when decreasing the sample size (increasing the surface-to-volume ratio). The original finding was the presence of two maxima in the isothermal polymerization rate (a double gel effect), a fact that was confirmed by replicating experiences in two different DSC devices and changing the amount of initiator in the formulation. The first maximum in the polymerization rate was explained by the decrease of the diffusion rate of macromolecular radicals to the oxygen-rich boundary, an effect that starts at low conversions. The second maximum was related to the decrease in the solubility/diffusion of oxygen in the reaction medium, a phenomenon that is particularly severe at high conversions.
SUSPENSION POLYMERIZATION OF ACRYLONITRILE
丙烯腈的悬浮聚合

WU Cheng-xun,HE Jian-ming,SHI Fei-zhou,
吴承训
,何建明,施飞舟

高分子学报 , 1991,
Abstract: Ultra high molecular weight polyacrylonitrile of Mw = 4.0~17.8×105 was obtained by suspension polymerization, using azobisisobutyronitrile as initiator and polyvinyl alcohol as suspension agent. The effects of temperature, time, stirring rate, initiator concentration, and monomer to water ratio on the polymerization and the polymer obtained are investigated. By using this method, ultra high molecular weight copolymers of acrylonitrile with methyl acrylate, a-methyl acrylic acid can be also synthesized.
Preparation of Polymer Composite Particles by Phase Separation Followed by Suspension Polymerization  [PDF]
Yoshinari Taguchi, Takanori Suzuki, Natsukaze Saito, Hiroshi Yokoyama, Masato Tanaka
Open Journal of Composite Materials (OJCM) , 2017, DOI: 10.4236/ojcm.2017.71001
Abstract:
The novel method for preparing the polymer composite particles has been developed. It was tried to prepare polymer composite particles composed of polystyrene and carbon black with the phase separation method followed by suspension polymerization. In order to prepare the polymer composite particles with the more uniform diameter, the styrene monomer droplets containing carbon black were formed with phase separation emulsification in which ethyl alcohol and water were used as the good solvent and the poor solvent for styrene monomer, respectively. In the experiment, the surfactant species and their concentrations, the pouring velocity of water and the weight ratio of carbon black to styrene monomer were mainly changed. Water was poured at the given pouring velocity into ethyl alcohol in which styrene monomer and an initiator were dissolved and carbon black was dispersed beforehand. The spherical polymer composite particles containing carbon black were prepared with Tween 20 and Tween 80 of nonionic surfactants and the irregular polymer composite particles were prepared with PVA, SDS and Kotamine. The diameters of polymer composite particles increased with the pouring velocity of water and with the weight ratio of carbon black to styrene monomer.
Preparations of spherical polymeric particles from Tanzanian cashew nut shell liquid by suspension polymerization
LL Mkayula, YMM Makame, TH Matechi
Tanzania Journal of Science , 2004,
Abstract: Spherical Polymeric Particles (SPP) have been prepared from Tanzanian Cashew Nut Shell Liquid (CNSL) by suspension polymerization technique involving either step-growth or chain- growth polymerization mechanisms. The sizes of the SPP, which ranged from 0.1 to 2.0 mm were strongly influenced by the amounts of stabilizers in polymerization recipes used. The particles showed variable surface areas, indicative of the presence of pores in some of the preparations and the highest surface area recorded was about 260 m2g-1. The particles were found to exhibit Langmuir-type adsorption isotherms with saturation capacity of about 9.0 and 44.2 mg/g for Na+ and Ca2+, respectively. Step-growth polymerization produced SPP with relatively smaller surface areas and lower adsorption capacities of sodium and calcium ions compared to the particles produced through the chain-growth mechanism. Other particle characteristics depended strongly on the recipe employed and the surface OH functional groups apparently determine the potential applications of the SPP. Tanzania Journal of Science Vol. 30 (2) 2004: pp. 1-10
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