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  • 11
    Electronic Resource
    Electronic Resource
    Study on aqueous polymerizations of vinyl monomers initiated by metal oxidant-chelating agent redox initiators (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 3213-3222 
    Details
    ISSN: 0887-624X
    Keywords: redox initiators ; chelating type reductants ; metal oxidants ; mechanism ; characterization of kinetic parameters ; aqueous polymerizations of vinyl monomers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this study, a series of chelating type reductants containing redox pairs were tested as the initiator for aqueous polymerizations. The redox pairs consist of Ce(IV) or several first-row transition metals coupled with chelating agents of amino acids, dibasic acids, or diamine. The initial rates and limiting conversions of acrylamide polymerization initiated by those redox pairs were determined. The reductive reactivity of the chelating agents with Ce(IV) and the oxidative half-wave potential of Ce(III)-chelating agent/Ce(IV)-chelating agent were measured to evaluate the feasibility of these redox pairs as initiators. After the evaluation, the redox pairs other than Ce(IV)-amino acid type chelating agent were precluded to be promising initiators for aqueous polymerizations. Those Ce(IV)-amino acid type chelating agent redox pairs which could form at least two five- or six-membered rings were found to be potential initiators. The Ce(IV)-NTA pair was the most promising one. The mechanism of initiation of the redox pairs was proposed and further confirmed by the 13C- and 1H-NMR spectra of NTA-terminated polyacrylamide. The complex formation constants (K) and disproportionation constants (kd) of the Ce(IV)-amino acid type chelating agent redox initiators for acrylamide polymerization were evaluated. The factors governing the parameters of chelated complexes and the performance of polymerizations were discussed. These redox pairs were also used as the initiators for aqueous polymerizations of acrylic acid and acrylonitrile. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080311307
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  • 12
    Electronic Resource
    Electronic Resource
    The effect of sodium methacrylate on the soapless emulsion copolymerization of methyl methacrylate and n-butyl acrylate (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 709-718 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The soapless emulsion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containing various concentrations of sodium methacrylate (NaMA) or methacrylic acid (MMA) is studied. The hydrosoluble yields in final latexes are not larger than 1.3-5%, depending on the concentration of NaMA used. Below 25% conversion, the change of conversion with reaction time follows the square rule and the particle size is proportional to the 2/3 power of time. Above 25% conversion, serious gel effect occurs, and the conversion follows the seventh power on time and the growth of particle diameter obeys the 2.5 power on time. The multiple glass transition (Tg) occur below 20% conversion, where monomer droplets exist. NaMA added induces more Tgs. The effect of molecular weight of the copolymers obtained on Tg (even the molecular weight distributions were shown to be shouldertype bimodal) is estimated to be insignificant. Thus, the heterogeneity of copolymer compositions for multiple Tgs is ascribed to be caused from neither the molecular weight heterogeneity nor the shifts in compositions due to the difference of the monomer reactivity ratios. Referring to the results mentioned, we assume the sublayer surrounding the particle, rich with SO4- and COO- groups, and the concentration gradients of monomers in particles to illustrate particle morphology. In addition, the relatively hydrophilic sublayer is proposed to be closely relative with the occurrence of the composition heterogeneity in particles.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290513
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  • 13
    Electronic Resource
    Electronic Resource
    Study on the continuous loop tubular reactor for emulsion polymerization of styrene (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 187-192 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A continuous loop tubular reactor (CLTR) with a Bodenstein number of 100 and a recycle ratio of 0.992 (obtained under the conditions of a mean residence time of 25.0 to 59.95 min and a stirring rate of 418 rpm) was used for studying the emulsion polymerization of styrene (St). The recipe used in the study is 76.8 g St/l-water, 3.73 g sodium lauryl sulfate (SLS)/l-water, and 2.30 g potassium persulfate (KPS)/l-water. The effects of the mean residence time on the performance of emulsion polymerization were studied. The overshoots in the monomer conversion and the particle number concentration were found to be higher as the mean residence time increased. The overshoots diminished at about 3 times the mean residence time. The steady state particle number concentration was independent of the mean residence time, while the steady state monomer conversion increased with increasing mean residence time.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300308
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  • 14
    Electronic Resource
    Electronic Resource
    The performance of the emulsion polymerization of styrene in a continuous loop tubular reactor (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 198-205 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The emulsion polymerization of styrene in a continuous loop tubular reactor (CLTR) has been used to study the process kinetics under eigth levels of sodium lauryl sulfate (SLS) concentration, eight levels of potassium persulfate (KPS) concentration, and three levels of styrene monomer (St) concentration. A critical surfactant concentration for the overshoot phenomenon in the monomer conversion exists between 8.02 and 12.40 g-SLS/1-water. Overshoot was not eliminated by changing concentrations of the initiator and monomer. The overshoot in the number concentration of polymer particles was observed in all the polymerizations studied. The dependences of the rate of polymerization and the number concentration of particles in the steady state on the SLS and KPS concentrations are presented. The growth of the average cumulant diameter of particles shows a transient period followed by a steady state. The dependences of the volumetric growth rate of polymer particles on diameter are of the order of 1 for the lower SLS concentration and 0.5 for the higher SLS concentration, respectively. The steady state cumulant diameter depends on an order of -0.24 for the SLS concentration.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760320306
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  • 15
    Electronic Resource
    Electronic Resource
    Emulsion polymerization of butyl acrylate induced by sodium lauryl sulfate/hydroxymethane sulfinate (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 231 (1995), S. 15-24 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Hydroxymethansulfinat (SFS) wurde zusammen mit Laurylsulfat (SLS) zur Initiierung der Polymerisation von n-Butylacrylat (n-BA) in Wasser verwendet. Die Reaktionsgeschwindigkeiten, Molekulargewichte und Latexstabilitäten erwiesen sich als vielversprechend. Die Polymerisationen verliefen jedoch nur bis zu einem bestimmten Grenzumsatz mit breiten Molekulargewichts- und Teilchengrößenverteilungen. Das u. a. von den Konzentrationen an n-BA, SFS und SLS abhängende Polymerisationsverhalten unterscheidet sich von dem herkömmlicher Emulsionpolymerisationen. Die Abhängigkeit der Polymerisationsgeschwindigkeit von der Temperatur läßt sich mit der Arrhenius-Gleichung beschreiben; die Gesamt-Aktivierungsenergie beträgt 43 kJ/mol, was annähernd dem Wert von mit Redox-Initiatoren initiierten Polymerisationen entspricht.
    Notes: Hydroxymethane sulfinate (sodium formaldehyde sulfoxylate, SFS) along with sodium lauryl sulfate (SLS) was used to induce the aqueous polymerization of n-butyl acrylate (n-BA). The reaction rate, molecular weights and latex stability with those two compounds were found to be promising. However, the polymerization involved a significantly limited conversion and broad dispersity in molecular weights and particle sizes. The polymerization behavior, depending on factors such as the concentrations of SFS, SLS and n-BA was different from that of traditional emulsion polymerizations. The rate dependence on the reaction temperature was described well by the Arrhenius equation, and the overall activation energy of polymerization thus obtained was 43 kJ/mol, which is close to that of redox-induced polymerizations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052310102
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  • 16
    Electronic Resource
    Electronic Resource
    Dimerizations of acrylate monomers with sodium hydroxymethanesulfinate and characterization of the products (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 1493-1502 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reactions of sodium hydroxymethanesulfinate (sodium formaldehyde sulfoxylate, SFS) with various monomers, including acrylates, methacrylates, styrene and vinyl acetate, were studied. The reaction products formed depended on the molecular structure of the monomers and acidity of the reaction solution. Among the monomers studied, acrylates with resonance stability values Q between 0,38 and 0,45 produced diacrylate sulfones in neutral conditions. The other monomers or reaction conditions did not result in a dimer. The obtained diacrylate sulfones were characterized by elemental analysis, mass spectrometry, IR spectra, normal 1H and 13C NMR, CHn (n = 1, 2 and 3) subspectra by Distortionless Enchancement by Polarization Transfer at θ = 3π/4, as well as by 1H- 13C 2D-NMR spectra using Correlated Spectroscopy and Heteronuclear Multiple Bonding Correlation methods. A possible reaction mechanism for the formation of dimers is suggested. The morphology and thermal properties of these diacrylate sulfones were determined.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021950504
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  • 17
    Electronic Resource
    Electronic Resource
    A method for the calculation of compositions of radical-chain copolymerizations (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 529-537 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this article the straight-line relationship between In A and B, where A and B denote the concentrations of the two types of monomers in any reaction period, is examined to exist in the radical copolymerizations of 1.02 ≥ r1r2 ≥ 0.25. Utilizing this observation, we propose an easy-to-use compositions calculation method in which a single empirical parameter is included. The method is derived without involving the constant monomer reactivity ratios assumption. The copolymerizations of styrene-methyl methacrylate vinyl chloride-vinyl acetate, methyl methacrylate-vinyl acetate, acrylic acid-acrylamide, methacrylic acid-methacrylamide, and sodium methacrylate-methacrylamide are investigated. The instantaneous and cumulative copolymer compositions and the residued monomer compositions computed by this proposal are in very good agreement with the experimental data.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070380312
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  • 18
    Electronic Resource
    Electronic Resource
    An X-ray investigation of terminally carboxyl oligo (ethylene oxide) monomethyl ethers-substituted side-chain liquid crystalline polysiloxanes (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 781-788 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 4′-[Oligo(ethylene oxide) monomethyl ether carbonyl] biphenyl-4-yl 4-(alkenyloxy) benzoate side-chain liquid crystalline (LC) polysiloxane polymers with various lengths of a terminal group and spacer were prepared. The mesophase structure and transition temperature of those polymers were investigated using methods of X-ray diffraction, polarized optical microscopy, and differential scanning calorimetry, respectively. The mesophases of the polymers were smectic ones. The layer spacing d1s and the side-chain distance of d2s obtained were around 29-34 Å and 4.4-4.6 Å, respectively. d1s were much shorter than twice the lengths of the side chains presumed in the fully extended conformation. Hence, the two-layer end-on packings or the packing with overlapping of tails model seemed not able to interpret the mesophase structure of those polymers studied. The effects of temperature on the mesophase microstructure of 4′-[ethylene oxide monomethyl ether carbonyl] biphenyl-4-yl 4-(pentenyloxy) benzoate side-chain LC polysiloxane polymer were also studied using the X-ray diffraction method. It was found that both d1 and d2 of the polymer in the mesophase temperature range became shorter with decreasing temperature and the long-and short-range order could remain, to some extent, at temperatures above the isotropic transition temperature and temperatures below the melting temperature. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470504
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  • 19
    Electronic Resource
    Electronic Resource
    Adiabatic anionic polymerization of caprolactam in the presence of N-acylated caprolactam macroactivator: Kinetic study (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1671-1681 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this study, bis ∊-caprolactam bis-diphenyl methane diisocyanate polypropylene glycol 1000 used as the macroactivator was prepared and well characterized prior to use. The anionic polymerization of ∊-caprolactam with the macroactivator as a function of the macroactivator concentration was adiabatically carried out. The adiabatic temperature rise method as well as the macrokinetics were used for elucidation of the kinetics of the polymerization. A nonlinear regression technique was used for determining the parameters of the macrokinetic equation. The equilibrium conversion and equilibrium time obtained were 94-96% and 2-9 min depending on the macroactivator concentration. The effects of the concentrations of macroactivator and ∊-caprolactam on the initial rate, apparent overall reaction rate, and the empirical parameters were studied. A side reaction induced by the transfer of the proton in the isocyanurate group of the macroactivator to caprolactam anion was found. According to this finding, a new reaction kinetic model was proposed by properly modifying the macrokinetic equation. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070501001
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  • 20
    Electronic Resource
    Electronic Resource
    Synthesis and mesomorphic behavior of terminal oligo(ethylene glycol)monomethyl ether-substituted low molecular weight thermotropic liquid crystals (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 1687-1697 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A number of alkenyl monomers containing biphenyl benzoate-based on a mesogenic core with various lengths of oligo(ethylene glycol) monomethyl ether as the terminal group were synthesized. The purity, the thermotropic transition temperature, and the mesomorphic texture were investigated with 1H-nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and optical polarized microscopy with a hot stage. The monomers studied in this project showed predominately nematic phases, whereas those with esterlinked derivatives studied in our previous work were able to present both nematic and smectic phases. They also exhibited higher isotropic transition temperatures than those of the ester-linked derivatives. The factors governing mesophase texture and transition temperature are discussed thoroughly. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070531215
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