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  • 1975-1979  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Emulsion polymerization kinetics and its reactor design. II. The MWD behavior in isothermal batch operation (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 2049-2063 
    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: The emulsion polymerization of styrene in an isothermal batch operation can be divided into three stages, and the corresponding kinetic rate equations are obtained from the experimental conversion-reaction time curve. The course of polymerization between the beginning of the reaction and any subsequent time is successfully computed for the reaction rate, the MWD, and the average degree of polymerization using the intergrals of these rate equations, which could readily explain the behavior of the emulsion polymerization. A comparison is made between the theoretical results and the experimental data. Both the theoretical treatment and the experimental data predict that the MWD for a typical emulsion polymerization is characterized by the rapid decrease in Mw/Mw ratio at the entrance of the zero-order stage and a gradual increase in the first-order stage regardless of an autoacceleration effect. An autoacceleration effect in the first-order stage is, however, evidence for a typical emulsion polymerization.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230715
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The kinetics of polyesterification. III. A mathematical model for quantitative prediction of the apparent rate constants (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 1797-1803 
    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 mathematical model for the apparent constants k1 and k2 which presents a quantitative explanation of the observed kinetic behavior in both uncatalyzed and acid-catalyzed polyesterification between ethylene glycol and a dibasic acid in different initial molar ratios was developed. This model consists of two types of similar semiempirical equations, one of which applies to the uncatalyzed reaction and the other to the acid-catalyzed reaction. They are both based on the same apparent dissociation coefficient, kh, of a dibasic acid in ethylene glycol, which can be expressed as kh = K ear at constant temperature. The symbol a in the equation represents the sensitivity constant to change in the initial molar ratio r = [OH]0/[COOH]0. The value of the true rate constant for polyesterification between succinic acid and ethylene glycol at 195°C was estimated to be 3.02 × 10-3 [in kg2/(equiv. moles)2·min] based on this model.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1978.070220705
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation model for the solution copolymerization of acrylonitrile and styrene in azeotropic composition (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 1203-1222 
    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: The rate of chemical-initiated solution copolymerization of acrylonitrile and styrene in toluene as solvent was studied theoretically and experimentally with a limiting conversion of about 50%. Taking into consideration industrial operation, the polymerization was carried out under an azeotropic composition of AN:St = 25:75 by weight, and a new kinetic model is proposed for estimating the conversion and the rate of polymerization as well as the molecular weight distribution over the entire reaction course. It is shown that the experimental data of conversion and the rate of reaction, as well as average molecular weight, can be successfully correlated to limiting conversion by this model if the effect of change in the initiator efficiency during the reaction on the rate of reaction is taken into consideration. It was found that the effective initiator efficiency can be expressed as f = 0.0956([A0] + [S0]). Some important kinetic constants as well as model parameters are obtained by simulation of this model, which agree with the experimental results. Certain transfer constants obtained by this simulation model are kf12 = 30 × kf11 and kf21 = 5 × kf22. Within the limiting conversion studied, no significant autoacceleration is observed. It is therefore not necessary to include this effect in the model.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230423
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The kinetics of polyesterifications. IV. Polyol from BHET and adipic acid and its urethanes (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 1169-1178 
    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: New polyol containing aromatic rings was prepared from BHET, or BHET/ethylene glycol mixtures and adipic acid. In this new system, the kinetics of polyesterification were investigated and were shown to follow the kinetic equations proposed by Lin and his co-workers which were obtained by modifying Flory's theory. Polyurethane elastomers were prepared by reacting these polyols and toluene diisocyanate (TDI) in DMF solution with NaCN as a crosslinking catalyst at room temperature. Their physical properties such as density, gel fraction, swelling ratio, mechanical properties, etc., were measured. High values of elastic modulus are due to the rigid segment of BHET. By varying the molar ratio of diisocyanate and polyester, polyurethanes with different crosslinking densities can be obtained. The relationship between physical properties and crosslinking density was shown to follow the general theory of rubber elasticity.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240503
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The kinetics of polyesterification. I. Adipic acid and ethylene glycol (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 2711-2719 
    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: The polyesterification between adipic acid and ethylene glycol in nonequimolar ratios was investigated. The kinetic equations obtained were quite different from those obtained by Flory in equimolar systems. The kinetic equations obtained in this study were -d[COOH]/dt = k[COOH][OH]2 for uncatalyzed polyesterification and -d[COOH]/dt = k[COOH]2 for catalyzed polyesterification. The mechanism of the polyesterification of a dibasic acid and a glycol can only be explained by the dissociation effect of hydrogen ion from dibasic acid in glycol.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070211012
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  • 6
    Electronic Resource
    Electronic Resource
    The kinetics of polyesterification. II. Succinic acid and ethylene glycol (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 1005-1016 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polyesterification of succinic acid with ethylene glycol in both equimolar and nonequimolar ratios was investigated at the reaction temperature of 195°C. The experimental results agreed quite well with the kinetic equations proposed in our previous paper for the adipic acid-ethylene glycol system, except in the case of acid-catalyzed equimolar reaction, where a shift of kinetic behavior from reaction control to diffusion control would appear. The apparent rate constants for uncatalyzed and acid-catalyzed reactions were evaluated by using the method of least squares for various values of initial molar ratio between [OH] and [COOH]. The dissociation effect of hydrogen ion from dibasic acid in glycol, as proposed in the adipic acid-ethylene glycol system, could also be applied in the succinic acid-ethylene glycol system to explain the kinetic behavior observed. The kinetic equations previously proposed for polyesterification were again confirmed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.170160512
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    Paper (German National Licenses)
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