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  • 1
    Electronic Resource
    Electronic Resource
    Study of the isothermal bulk polymerization of vinyl acetate by differential scanning calorimetry (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 1507-1511 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit Hilfe der Abtast-Kalorimetrie (DSC) wurden der Verlauf und die Kinetik der isothermen Polymerisation des Vinylacetates in Masse studiert. Als Initiator wurde 2,2′-Azoisobutyronitril verwendet. Die Polymerisation wurde bei Temperaturen zwischen 55 und 70°C mit konstanter Initiatormenge, 5,0.10-2 mol/l, ausgeführt. Die Polymerisationswärme beträgt bei 60°C - 19,5 kcal/mol und nimmt mit steigender Temperatur ab. Es wurden auch Geschwindigkeitskonstanten der Polymerisation im stationären Zustand und aus ihnen die Bruttoaktivierungsenergie zu 21,6 kcal/mol bestimmt. Eine andere Reihe von Experimenten wurde bei 60°C mit verschiedenen Initiatormengen durchgeführt. Die Bruttogeschwindigkeit der Polymerisation bei kleinen Umsätzen ist der Wurzel der Initiatormenge proportional, was dem angenommenen kinetischen Schema entspricht.
    Notes: The course and kinetics of the isothermal bulk polymerization of vinyl acetate were studied by differential scanning calorimetry. The initiator used was 2,2′-azoisobutyronitrile. The polymerization was investigated at temperatures between 55 and 70°C at constant initiator concentration, 5,0.10-2 mol/l. The heat of polymerization at 60°C is - 19,5 kcal/mol and decreases with increasing temperature. Initial rate constants for the polymerization were also determined and from them the overall activation energy, 21,6 kcal/mol. Another series of polymerization experiments were performed at 60°C with variable amounts of the initiator. The overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration which is in agreement with the assumed kinetic scheme.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021750512
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  • 2
    Electronic Resource
    Electronic Resource
    Study of the isothermal bulk polymerization of methyl methacrylate by differential scanning calorimetry (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 873-880 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit Hilfe der Differential-Scanning-Kalorimetrie (DSC) wurden der Verlauf und die Kinetik der isothermen Polymerisation des Methylmethacrylates in Substanz untersucht. Als Initiator wurde 2,2′-Azoisobutyronitril verwendet. Die Polymerisation wurde bei Temperaturen zwischen 70 und 90°C mit konstanter Initiatorkonzentration, 5,2.10-2 mol/dm3, ausgeführt. Die Polymerisationswärme beträgt bei 70°C -52,3 kJ/mol (-12,5 kcal/mol) und nimmt mit steigender Temperatur ab (sie wird negativer). Es wurden auch Geschwindigkeitskonstanten der Polymerisation im stationären Zustand und aus ihnen die Bruttoaktivierungs energie 77 kJ/mol (18,4 kcal/mol) bestimmt, die gut mit Literaturangaben übereinstimmt. Eine andere Reihe von Experimenten wurde bei 80°C mit verschiedenen Initiatormengen durchgeführt. Der dabei gefundene Wert der Polymerisationswärme -52,8 kJ/mol (-12,6 kcal/mol) ist von der Initiatormenge nur wenig abhängig. Die Bruttogeschwindigkeit der Polymerisation bei kleinen Umsätzen ist der Wurzel aus der Initiatorkonzentration proportional. Diese Ergebnisse zeigen in Übereinstimmung mit den Befunden anderer Autoren, daß die Scanning-Kalorimetrie eine brauchbare Methode zum Studium der Kinetik der Polymerisation ist.
    Notes: Course and kinetics of the isothermal bulk polymerization of methyl methacrylate were studied by differential scanning calorimetry. The initiator used was 2,2′-azoisobutyronitrile. The polymerization was investigated at temperatures between 70 and 90°C at constant initiator concentration, 5,2.10-2 mol dm-3. The heat of polymerization at 70°C is -52,3 kJ/mol (-12,5 kcal/mol) and decreases, i.e. becomes more negative, with increasing temperature. Initial rate constants for the polymerization were also determined and from them the overall activation energy, 77 kJ/mol (18,4 kcal/mol), which is in good agreement with the literature value. Another series of polymerization experiments were performed at 80°C with variable amounts of the initiator. The heat of polymerization found is -52,8 kJ/mol (-12,6 kcal/mol) and depends only slightly on the initiator concentration. The overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration. These findings thus corroborate the conclusion reached by other authors that differential scanning calorimetry is a useful method for studying the kinetics of polymerization.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021750314
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  • 3
    Electronic Resource
    Electronic Resource
    Study of the reaction between 1,5-naphtalene diisocyanate and polycaprolactone in different solvents (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1573-1580 
    Details
    ISSN: 0887-624X
    Keywords: polyurethanes ; solution polymerization ; naphtalene diisocyanate ; kinetics ; NMR spectroscopy ; size exclusion chromatography ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between polycaprolactone and 1,5-naphtalene diisocyanate has been investigated in solvents with different dielectric constants and hydrogen bonding powers (toluene, ethyl acetate, ethyl methyl ketone), and in the same solvents with the addition of a catalytic amount of dimethyl sulfoxide (DMSO). The reaction was considered to proceed over two steps, the reaction of the first NCO group being faster. The course of the reaction was measured by titration of the unreacted NCO groups, 1H- and 13C-NMR spectroscopy, and size exclusion chromatography. By titration only the overall reaction order and reaction rate constants could be determined. DMSO accelerated the reaction in all three solvents, which was explained by the stabilization of the activation complex by DMSO. Both steps of the reaction could be specified by NMR spectroscopy. The ratio between the reaction rate constants for the first and the second step decreased with the increased hydrogen bonding strength of the solvent and with DMSO. By SEC only the reaction of the first NCO group could be determined due to the low resolution for higher molar mass reaction products with a broad distribution. The values obtained for the first step reaction rate constants were in good agreement with NMR values. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331003
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of kinetic parameters for thermal decomposition of polymerization initiators by differential scanning calorimetry (1975)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 46 (1975), S. 89-94 
    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: Für die Bestimmung kinetischer und thermischer Parameter beim Zerfall einiger Polymerisationsinitiatoren wurde die Differential-Scanning-Kalorimetrie (DSC) verwendet. Die Initiatoren wurden in Di-n-butylphthalat gelöst. Die Messungen erfolgten im Temperaturbereich zwischen 50°C und 180°C. Die Aktivierungsenergien wurden für Azobisisobutyronitril zu 137,5 kJ/mol (32,9 kcal/mol) und für Benzoylperoxid zu 119,6 kJ/mol (28,6 kcal/mol) gefunden, was mit Literaturangaben übereinstimmt. Die Aktivierungsenergie des technischen Lauroylperoxids und technischen Methylüthylketonperoxids beträgt 141,7 kJ/mol (33,9 kcal/mol) bzw. 181,4 kJ/mol (43,4 kcal/mol). Diese zwei Werte sind höher als die in der Literatur gefundenen, wahrscheinlich weil technische Produkte untersucht wurden.Es wurden auch die Zerfallswärmen der Initiatoren bestimmt. Sie betragen: -230,7 kJ/mol (-55,2 kcal/mol) für Azobisisobutyronitril, -293,0 kJ/mol (-70,1 kcal/mol) für Benzoylperoxid, -693,5 J/g (-165,9 cal/g) für Lauroylperoxid und -459,8 J/g (-110,0 cal/g) für Methyläthylketonperoxid.
    Notes: The kinetic and thermal parameters for the decomposition of a group of polymerization initiators were determined using differential scanning calorimetry (DSC). The solvent was di-n-butylphthalate, and the measurements were made in the temperature range between 50°C and 180°C. The activation energies for azobisisobutyronitrile and benzoyl peroxide are 137.5 kJ/mol (32.9 kcal/mol) and 119.6 kJ/mol (28.6 kcal/mol), respectively, which is in agreement with literature values. The activation energies for technical lauroyl peroxide and technical methylethylketone peroxide are 141.7 kJ/mol (33.9 kcal/mol) and 181.4 kJ/mol (43.4 kcal/mol), respectively, and are higher than the values reported in the literature. This is probably due to the fact that technical samples were used.The heats of decomposition were also obtained. They are - 230.7 kJ/mol ( - 55.2 kcal/mol) for azobisisobutyronitrile, - 293.0 kJ/mol ( - 70.1 kcal/mol) for benzoyl peroxide, - 693.5 J/g ( - 165.9 cal/g) for lauroyl peroxide, and -459.8 J/g ( - 110.0 cal/g) for methylethylketone peroxide.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1975.050460109
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  • 5
    Electronic Resource
    Electronic Resource
    Study of curing of epoxy resins by acid anhydrides using differential scanning calorimetry (1975)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 44 (1975), S. 89-97 
    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: Unter Anwendung der Differential-Scanning-Calorimetrie (DSC) wurden der Verlauf und die Kinetik der Härtung von Epoxid-Harzen untersucht. Es wurde gefunden, daß die Reaktionswärme bei 107,5°C, in Abhängigkeit von der Zusammensetzung des Reaktionssystems, zwischen -302,2 und -333,2 J/g (-72,2 bis -79,6 cal/g) beträgt. Für ein System wurden die Messungen bei drei verschiedenen Temperaturen durchgeführt. Aus den DSC-Kurven wurden die Reaktionsordnung und die Reaktionsgeschwindigkeitskonstanten bestimmt. Es wurde gefunden, daß die Reaktion zwischen 18 und 80% Umsatz nach der Ordnung 0,5 und zwischen 80 und 98% Umsatz nach der ersten Ordnung verläuft. Aus den Geschwindigkeitskonstanten wurden nach der Arrheniusschen Gleichung die Aktivierungsenergien ausgerechnet, und zwar für die 0,5te Ordnung 58,2 KJ/mol (13,9kcal/mol) und für die erste Ordnung 56,1 KJ/mol(13,4kcal/mol).
    Notes: Course and kinetics of the curing of epoxy resins by acid anhydrides were studied by differential scanning calorimetry (DSC). The heat of reaction at 107.5°C was found to lie between -302.2to -333.2 J/g (-72.2 to -79.6 cal/g), depending on the composition of the reaction system. For one reaction system measurements were made at three different temperatures. From DSC data the reaction order and rate constants were evaluated. Between 18 to 80% conversion the curing reaction was found to be 0.5 order, and from 80 to 98% conversion to be first order. From the rate constants using the Arrhenius equation the activation energy was calculated. The values of the activation energy are 58.2 KJ/mol (13.9 kcal/mol) for 0.5 order and 56.1 KJ/mol (13.4 kcal/mol) for first order reaction.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1975.050440107
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of oligomers from 1,4-butanediol and toluene diisocyanate (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 805-814 
    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: Polyurethane oligomers from 1,4-butanediol (BD) and toluene diisocyanate (TDI) with a various excess of BD were synthesized. Their molar masses were measured by gel permeation chromatography and the molar mass distribution correlated with the statistic theory. 1H-, 13C-, 1H-1H-COSY-, ATP-, and 15N-NMR spectra of reaction products were recorded, and from the ratio of proton integrals of characteristic terminal and inner urethane groups, the reactivity ratio of the para and ortho NCO groups in 2,4-TDI was calculated to be approximately 1.8 at a lower excess of BD. 15N-NMR spectroscopy was found not to be selective enough to detect small amounts of side reactions. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470507
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