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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1184-1189 
    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: Application of shear is found to increase the rate of solution polymerization of acrylonitrile in N,N-dimethyl formamide (DMF) initiated by benzoyl peroxide by as much as 400 percent of the value in absence of shear. The solvent DMF acts as an inert and maintains a homogeneous reaction mass during the entire course of polymerization. To study the effect of shear systematically, a special dilatometer has been constructed such that a constant shear rate, \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \gamma \limits^. $\end{document} could be applied to the reaction mass. The rule of solution polymerization has been measured under the variation of \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \gamma \limits^. $\end{document} and monomer concentration in the system. The measurements of induction time on the addition of a strong inhibitor, hydroquinone, reveal that the increase in the rate of polymerization with shear rate can be largely attributed to the change in the initiator efficiency. As a further confirmation of the above hypothesis, the decomposition of benzoyl peroxide in nitrobenzene at 80°C was measured and was found to increase significantly on application of shear. This confirms the importance of mass-transfer resistance in removal of CO2, and the increase in the rate of polymerization of acrylonitrile occurs because the decomposition of benzoyloxy radicals is favored in the forward direction. Since the polymerization of acrylonitrile is preferentially initiated by phenyl radicals, the rate of polymerization is found to increase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 32 (1986), S. 1561-1566 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 42-51 
    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: Intramolecular reactions in the step-growth polymerization of multifunctional monomer, RAf, were modeled. The rate constant for this step was taken from the Monte Carlo studies of Plate and Noah. Species Pvn, with v Intramolecular bonds and chain length n, was defined, and differential equations governing their molecular weight distribution (MWD) in hatch reactors were written. An algorithm of computation valid up to the gel point was developed, and the process of gelation was studied under the variation of the rate constant parameters of the intramolecular reaction step. It was found that the larger the molecule, the greater is its tendency to form intramolecular bonds. We devised a mathematical method to find the conversion of A groups on Pon species. Whenever this reaches a critical value {= l/(f-1)}, conditions for gelation are generated and molecules of infinite structure begin to form. In the presence of intramolecular reactions, the tendency to form a network is reduced because larger molecules undergo cyclization and there is consequently a shift in the gel point, which has been computed in this work.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 925-933 
    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 functional group approach that accounts for the formation of higher oligomers was used in modeling the batch polymerization of melamine and formaldehyde. Five rate constants are required instead of 24 as needed in earlier studies to fit experimental data in the entire range. The model presented allows the formation of higher oligomers even though their formation is small. The batch polymerization of melamine and formaldehyde was studied under a wide variation of reaction parameters to find conditions that would lead to formation of higher oligomers preferentially.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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