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Copolymerization System (copolymerization + system)
Selected AbstractsNovel divinyl monomer for preparation of unsaturated polymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Song Chen Abstract To simplify the preparation of unsaturated polymers, a new type of divinyl monomer was designed in this article. The double bonds of the divinyl monomer are different not only in reactivity but also in electron density. Based on quantum chemistry calculation, (z)-4-(2-(acryloyloxy)ethoxy)-4-oxobut-2-enoic acid (cis -AEOEA) was selected as the nonelectron-donating divinyl monomer in which inactive double bond was electron deficient and can be activated by electron-donating comonomers by forming charge transfer complex (CTC) copolymerization system. So, cis- AEOEA can be used to simplify the preparation of unsaturated polymers and the content of inactive double bonds left in the polymer is controlled by electron-donating ability of comonomers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Kinetic study of methacrylate copolymerization systems by thermoanalysis methodsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Ali Habibi Abstract The free-radical solution copolymerization of isobutyl methacrylate with lauryl methacrylate in the presence of an inhibitor was studied with thermoanalysis methods. A set of inhibited polymerization experiments was designed. Four different levels of initial inhibitor/initiator molar ratios were considered. In situ polymerization experiments were carried out with differential scanning calorimetry. Furthermore, to determine the impact of the polymerization media on the rate of initiation, the kinetics of the initiator decomposition were followed with nonisothermal thermoanalysis methods, and the results were compared with in situ polymerization counterparts. The robust M -estimation method was used to retrieve the kinetic parameters of the copolymerization system. This estimation method led to a reasonable prediction error for the dataset with strong multicollinearity. The model-free isoconversional method was employed to find the variation of the Arrhenius activation energy with the conversion. It was found that robust M -estimation outperformed existing methods of estimation in terms of statistical precision and computational speed, while maintaining good robustness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Online estimation and control of polymer quality in a copolymerization reactorAICHE JOURNAL, Issue 5 2002Myung-June Park The validity of an online state estimator for a semi-batch MMA/MA solution copolymerization reactor was established using online densitometer and viscometer. Using the conventional extended Kalman filter (EKF) as the state estimator, the experiment was conducted under both isothermal and nonisothermal conditions for application to the control of copolymer properties. Further analysis was made by using ofline measurement data for the mol fraction of MMA in the remaining monomers and the solid content. The EKF was found to provide a good estimate for the state of the copolymerization system. A model predictive controller was designed and implemented to obtain copolymers with uniform copolymer composition and the desired weight average molecular weight by adopting the feed flow rate of MMA and the reaction temperature as control inputs. The controller was proven effective with a satisfactory performance for the control of polymer properties in the semi-batch copolymerization reactor. [source] Selective preparation of poly(p -oxybenzoyl) by using fractional polycondensationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2006Kunio Kimura Abstract Selective preparation of poly(p -oxybenzoyl) (POB) in the copolymerization system of p -acetoxybenzoic acid (p -ABA) and m -acetoxybenzoic acid (m -ABA) was examined by using reaction-induced crystallization of oligomers. Polymer crystals mainly composed of p -oxybenzoyl moiety were precipitated when the content of m -ABA in the feed was 30 mol %. The formation of the polymer crystals was attributed to both the reactivity of monomer and the phase-separation behavior of oligomer. Reactivity of p -ABA was twice higher than that of m -ABA, and thereby, the homo-oligomers of p -oxybenzoyl moiety were more rapidly formed in solution than do co-oligomers at the early stage in polymerization. They were selectively precipitated by crystallization to form crystals because of low miscibility. Co-oligomers containing m -oxybenzoyl moiety were also formed in solution, but they were unable to be phase-separated because of higher miscibility. Further polycondensation occurred between oligomers in the precipitated crystals, leading to the formation of POB. This polymerization proceeded with selecting certain monomers by crystallization and afforded a new methodology for fractional polycondensation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2732,2743, 2006 [source] Preparation of gradient copolymers via ATRP using a simultaneous reverse and normal initiation process.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2005Abstract Spontaneous gradient copolymers were prepared in both bulk and miniemulsion systems via Atom Transfer Radical Polymerization (ATRP) utilizing a Simultaneous Reverse and Normal Initiation (SR & NI) process. Both instantaneous and cumulative compositions were used to characterize the gradient copolymers. The gradient copolymers were obtained with an array of gradient compositions ranging from a subtle to strong variation in monomer distribution along the polymer backbones, depending on the ratio of comonomers initially added to the copolymerization system. The compositions of the gradient copolymer produced in miniemulsion systems were similar to those generated in bulk. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3616,3622, 2005 [source] Preparation and properties of silicone-containing poly(methyl methacrylate) gelsPOLYMER INTERNATIONAL, Issue 11 2005Hamid Javaherian Naghash Abstract Poly(methyl methacrylate) (PMMA) gels with varying amounts of silicone and solvent and constant amounts of crosslinker were prepared by solution free radical crosslinking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) comonomer systems. They were then studied in benzene at a total monomer concentration of 3.5 mol L,1 and 70 °C. The conversion of monomer, volume swelling ratio, weight fraction and gel point were measured as a function of the reaction time, silicone concentration and benzene content up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in benzene, gel fraction and Fourier-transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by SEM. Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the VTES or TEOS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, Wg, and its equilibrium volume swelling ratio in benzene, qv, exhibited the same behaviour as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TEOS is not an ideal silicone compound for reaction in the MMA/EGDM copolymerization system, whereas VTES is a suitable silicone comonomer for this system and it has been proved useful. Copyright © 2005 Society of Chemical Industry [source] Kinetic study of methacrylate copolymerization systems by thermoanalysis methodsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Ali Habibi Abstract The free-radical solution copolymerization of isobutyl methacrylate with lauryl methacrylate in the presence of an inhibitor was studied with thermoanalysis methods. A set of inhibited polymerization experiments was designed. Four different levels of initial inhibitor/initiator molar ratios were considered. In situ polymerization experiments were carried out with differential scanning calorimetry. Furthermore, to determine the impact of the polymerization media on the rate of initiation, the kinetics of the initiator decomposition were followed with nonisothermal thermoanalysis methods, and the results were compared with in situ polymerization counterparts. The robust M -estimation method was used to retrieve the kinetic parameters of the copolymerization system. This estimation method led to a reasonable prediction error for the dataset with strong multicollinearity. The model-free isoconversional method was employed to find the variation of the Arrhenius activation energy with the conversion. It was found that robust M -estimation outperformed existing methods of estimation in terms of statistical precision and computational speed, while maintaining good robustness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] A kinetic study of the copolymerization of substituted anilines by 1H NMR,POLYMER INTERNATIONAL, Issue 10 2002Ida Mav Abstract We investigated the kinetics of oxidative chemical copolymerization of 2-methoxyaniline (OMA) with the following acidic substituted anilines (ANIAs): 2-aminobenzoic acid, 3-aminobenzoic acid, 2-aminobenzenesulfonic acid and 3-aminobenzenesulfonic acid by monitoring monomer depletion using 1H NMR spectroscopy. In order to characterize kinetically these new copolymerization systems, a semi-empirical kinetic model for copolymerization systems with a large difference in monomer reactivities was used, whereas the monomer reactivity ratios were determined by employing the Kelen,Tüdõs (KT) method. Owing to the much higher reactivity of OMA compared to that of ANIA monomers, the conversion of OMA starts before that of ANIA and both the initiation and propagation rates are higher than those for ANIAs. The ANIA end-conversion is much smaller (from 21 to 31%) than that of OMA (from 75% to 90%). © 2002 Society of Chemical Industry [source] | ||||||||||