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Copolymerization Parameters (copolymerization + parameter)
Selected AbstractsCopolymerization of ethylene with styrene catalyzed by a linked bis(phenolato) titanium catalystJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2006Carmine Capacchione Abstract Copolymerization of ethylene with styrene, catalyzed by 1,4-dithiabutanediyl-linked bis(phenolato) titanium complex and methylaluminoxane, produced exclusively ethylene,styrene copolymers with high activity. Copolymerization parameters were calculated to be rE = 1.2 for ethylene and rS = 0.031 for styrene, with rErS = 0.037 indicating preference for alternating copolymerization. The copolymer microstructure can be varied by changing the ratio between the monomers in the copolymerization feed, affording copolymers with styrene content up to 68%. The copolymer microstructure was fully elucidated by 13C NMR spectroscopy revealing, in the copolymers with styrene content higher than 50%, the presence of long styrene,styrene homosequences, occasionally interrupted by isolated ethylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1908,1913, 2006 [source] Thermally stable and high molecular weight poly(propylene carbonate)s from carbon dioxide and propylene oxide,POLYMER INTERNATIONAL, Issue 10 2002Q Zhu Abstract The copolymerization of carbon dioxide and propylene oxide was carried out to afford alternating poly(propylene carbonate) in high yield. Thermal stable and high molecular weight copolymers were successfully obtained by optimizing the reaction conditions. The catalyst used was zinc glutarate supported on a perfluorinated compound containing 7,12 carbon atoms. Copolymerization parameters, such as the ratio of propylene oxide to catalyst, stirring strength and purity of propylene oxide, were studied. The alternating copolymer with a molecular weight of 56,100 in a very high yield (126,g polymer per gram of catalyst) was achieved, which is the highest yield ever reported. The thermal and mechanical properties of the alternating PPC copolymer were examined by the means of modulated differential scanning calorimetry (MDSC), thermogravimetric analysis (TGA) and tensile test. MDSC and TGA results showed that the alternating PPC copolymer exhibits an extremely high glass transition temperature (maximum 46.46,°C) and decomposition temperature (255.8,°C) when compared to those values reported in literature. Tensile test revealed that thin film of alternating PPC copolymer exhibits superior mechanical strength. © 2002 Society of Chemical Industry [source] Radical and cationic polymerizations of 3-ethyl-3-methacryloyloxymethyloxetaneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2001Tsuneyuki Sato Abstract 3-Ethyl-3-methacryloyloxymethyloxetane (EMO) was easily polymerized by dimethyl 2,2,-azobisisobutyrate (MAIB) as the radical initiator through the opening of the vinyl group. The initial polymerization rate (Rp) at 50 °C in benzene was given by Rp = k[MAIB]0.55 [EMO]1.2. The overall activation energy of the polymerization was estimated to be 87 kJ/mol. The number-average molecular weight (M,n) of the resulting poly(EMO)s was in the range of 1,3.3 × 105. The polymerization system was found to involve electron spin resonance (ESR) observable propagating poly(EMO) radicals under practical polymerization conditions. ESR-determined rate constants of propagation (kp) and termination (kt) at 60 °C are 120 and 2.41 × 105 L/mol s, respectively,much lower than those of the usual methacrylate esters such as methyl methacrylate and glycidyl methacrylate. The radical copolymerization of EMO (M1) with styrene (M2) at 60 °C gave the following copolymerization parameters: r1 = 0.53, r2 = 0.43, Q1 = 0.87, and e1 = +0.42. EMO was also observed to be polymerized by BF3OEt2 as the cationic initiator through the opening of the oxetane ring. The M,n of the resulting polymer was in the range of 650,3100. The cationic polymerization of radically formed poly(EMO) provided a crosslinked polymer showing distinguishably different thermal behaviors from those of the radical and cationic poly(EMO)s. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1269,1279, 2001 [source] Copolymerization of Fluorinated Monomers with Hydrophilic Monomers in Aqueous Solution in Presence of CyclodextrinMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2006Oliver Kretschmann Abstract Summary: New fluorinated copolymers were synthesized by copolymerization of 1H,1H,2H,2H- perfluorodecyl methacrylate (1) with hydrophilic comonomers methacrylic acid (3), 2-acrylamido-2-methylpropane sulfonic acid (6), 3-trimethylammonium propyl methacrylamide chloride (7) and N,N -dimethylmethacrylamidopropyl- N -3-sulfopropylammoniumbetaine (8). The reaction was carried out in water using randomly methylated , -cyclodextrin (RAMEB) for solubilization of the fluorinated monomer by forming a host-guest complex (1a). Polymerization kinetics were investigated and copolymerization parameters were determined. Additionally, a RAMEB complex of tert -butyl methacrylate (2a) was copolymerized with 1a in water. For comparison, copolymerization of the uncomplexed monomers 1 and 2 were carried out in organic solvents. Evaluation of copolymerization kinetics and parameters showed significant differences in the relative reactivities of the free monomers and the monomer-RAMEB complexes. [source] Light-Induced Demixing of Hole or Electron Transporting MoietiesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 20 2004Marc Behl Abstract Summary: This paper describes the synthesis of two triphenylamine monomers (hole conducting) and one triazine monomer (electron conducting) which differ in their copolymerization parameters because of their styrene and vinyl ester nature. A blend of triphenylamine monomer and poly(ethylene glycol) and mixtures of both types of monomers (triphenylamine and triazine) were illuminated through a line mask, creating laterally modulated radicals, thus leading to lateral demixing. The experiments with mixtures of triphenylamine and triazine monomers show that the concentration of p- or n-type polymers can be modulated laterally in a controlled way. AFM measurement of line pattern formed by illuminating a mixture of monomer 2 and 3 showing the height difference between illuminated and non-illuminated areas. [source] On-line monitoring and fingerprint technology: new tools for the development of new catalysts and polyolefin materialsMACROMOLECULAR SYMPOSIA, Issue 1 2004Arno Tuchbreiter Abstract The High-Output Polymer Screening (HOPS) combines process-relevant automated reactor systems and rapid polymer characterization with on-line polymerization monitoring and automated data acquisition ("electronic notebook") in order to make effective use of advanced data mining tools. This has led to the development of fingerprint technology based upon correlations between spectroscopic data and polymerization process conditions, catalyst compositions, as well as polymer end-use properties. Infrared spectroscopic fingerprints proved to be very useful for accelerating polymer analyses including characterization of polymer molecular architectures as well as non-destructive testing of the mechanical, thermal and other end-use polymer properties. Such spectroscopic fingerprints represent important components of effective on-line quality control systems. With ATR-FT-IR probes on-line monitoring of catalytic olefin copolymerization was performed in solution to measure in real time copolymerization kinetics, catalyst productivities, catalyst deactivation as well as copolymerization parameters and copolymer sequence distributions. Monomer consumption and comonomer incorporation were monitored simultaneously. Advanced fingerprint technology can reduce significantly the need for time- and money consuming polymer testing and can also stimulate the search for new catalyst systems and polymeric materials. [source] Comprehensive Study of Free Radical Copolymerization Using a Monte Carlo Simulation Method, 1MACROMOLECULAR THEORY AND SIMULATIONS, Issue 5 2005Yousef Mohammadi Abstract Summary: In order to investigate the influence of reactivity ratios and initial feed composition on the microstructure of macromolecules in free radical copolymerization, a comprehensive study was carried out using a Monte Carlo simulation method. As a result, a new procedure was introduced to modify the works of others on the initiation step. The variation of the copolymer composition and the fashion of the arrangement of monomers in simulated chains were evaluated as a function of copolymerization parameters. The model was capable of monitoring any change in azeotropy as well as the magnitude and direction of composition drift from the azeotrope point. The maximum reachable conversion (MRC) was predicted for different combinations of initial feed compositions and reactivity ratios. According to the simulation results, a critical conversion where the macromolecules produced inherited the maximum allowed alternation was obtained for the reactivity ratios given. Change of sequence distribution of simulated copolymer chains with conversion for various initial feed compositions on a triangular graph (rA,=,0.5, rB,=,0.9). [source] | ||||||||||