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  • 1
    Electronic Resource
    Electronic Resource
    A comparative molecular weight study with particular reference to black wattle tannins (1958)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 33 (1958), S. 53-63 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Details are given of a further modification to the Ray ebulliometer which permits easy interchange of the Cottrell pump tube. The stability of the apparatus with different pump tubes and pumping conditions was also examined. Molecular weights obtained with the use of two ebulliometers and three solvent systems are compared. The validity of the recently developed ultracentrifuge methods for determining physical properties of molecules with molecular weights in the range 300 to 10,000 was checked by using a pure compound of known molecular weight. Agreement was obtained also between the data obtained by the Klainer and Kegeles method and separate sedimentation and diffusion data. The molecular weight of an ethyl acetate extract of black wattle tannin was determined by the ebulliometric and these ultracentrifuge methods. The ultracentrifuge value for the whole extract decreased with time due to sedimentation of high molecular weight impurities. The final ultracentrifuge weight-average molecular weight (1175) is in good agreement with the number-average value for the tannin polyphenols (922) obtained by ebulliometry. The difference between the values confirms the known heterogeneity of the polyphenols.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1958.1203312607
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  • 2
    Electronic Resource
    Electronic Resource
    Poly-α-ester degradation studies. VI. Thermal degradation of poly(3-pentylidene carboxylate) (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 123-146 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal degradation of poly(3-pentylidene carboxylate) has been studied kinetically over the temperature range 200-300°C using thermogravimetry, gas evolution analysis, and rheogoniometry together with isolation and analysis of the reaction products. The observed behavior is completely different from that previously reported for poly(isopropylidene carboxylate) and poly(methylene carboxylate). Whereas in the latter cases the decomposition occurs by a first-order intramolecular ester interchange process characterized by an activation energy in the region of 27 kcal mole-1, poly(3-pentylidene carboxylate) decomposition occurs by random chain scission superimposed on a first-order hydrogen abstraction process. The activation energy associated with this decomposition reaction is in the region of 47 kcal mole-1, and the major degradation products are cis- and trans-2-ethyl crotonic acid.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170180113
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  • 3
    Electronic Resource
    Electronic Resource
    Poly α-ester degradation studies. V. Thermal degradation of polyglycollide (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 2045-2056 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal degradation of polyglycollide [poly(methylene carboxylate)] has been studied over the temperature range 250-400°C by using the combined kinetic and analytical technique previously described. The results obtained from thermogravimetry and product analysis were in many ways similar to those from previous work involving higher poly-α-esters. Thus the reaction was predominantly first-order and the major degradation product was glycollide monomer. This confirms the observations of Carothers and is best interpreted in terms of an intramolecular ester interchange process. Kinetic studies have shown that the first-order rate constant k is related to temperature T by the expression: \documentclass{article}\pagestyle{empty}\begin{document}$$ k = 2.1 \times 10^8 e^{ - 32,{{600} \mathord{\left/ {\vphantom {{600} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}{\rm sec}^{ - {\rm 1}} } $$\end{document} The results from gas evolution analysis showed consistent and marked deviation from first-order behavior. This is interpreted in terms of the greater sensitivity of this technique to traces of acidic degradation products. Solution viscometry was used to demonstrate the effect of degradation conditions on molecular weight change in both thermogravimetric and gas evolution techniques.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110823
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  • 4
    Electronic Resource
    Electronic Resource
    Thermolysis of polystyrene (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 843-851 
    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: Styrene was recovered from polystyrene (molecular weight of 138,000) by thermolysis in a nitrogen atmosphere at temperatures between 368 and 407°C. The results were independent of the initial weight of polystyrene, which was varied between 30 and 480 g. Up to 90% of the polystyrene was converted to liquid products. The liquid products had a styrene concentration as high as 90% and the styrene yield increased with temperature. Above 390°C, the residue left in the reactor (less than 30% of initial polystyrene charge) consisted mainly of styrene monomer, dimer, and trimer (MW of 190). The kinetics support a first-order reaction with regard to the rate of production of volatiles. The activation energy was estimated to be 166.5 kJ/mol. © 1995 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580501
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics of glycolysis of poly(ethylene terephthalate) melts (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1731-1740 
    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 reaction of poly(ethylene terephthalate) (PET) melts with ethylene glycol was examined in a pressure reactor at temperatures above 245°C. The reaction rate was found to depend on temperature and on the concentrations of liquid ethylene glycol and of ethylene diester groups in the polymer. A kinetic model proposed for the initial period of the reaction was found to be consistent with experimental data. It was found that internal catalysis by ethylene glycol does not play an important role in the glycolytic depolymerization of PET. The rate constants for glycolysis were calculated for three different temperatures, yielding an activation energy of 92 kJ/mol. Zinc salts, which have a catalytic effect on glycolysis of PET below 245°C, do not appear to influence glycolysis rates above that temperature. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070541115
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  • 6
    Electronic Resource
    Electronic Resource
    Catalyzed hydrolysis of polyethylene terephthalate melts (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 985-991 
    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 effect of zinc catalysts on the hydrolytic depolymerization of polyethylene terephthalate (PET) melts in excess water was studied using a 2-L stirred pressure reactor at temperatures of 250, 265, and 280°C. The main products of the reaction were found to be terephthalic acid, ethylene glycol, and diethylene glycol. Rate constants were calculated from initial rate data at each temperature and found to be about 20% greater than the corresponding rate constants for uncatalyzed hydrolysis. The catalytic effect of zinc, as well as sodium, salts is attributed to the electrolytic destabilization of the polymer-water interface during hydrolysis. The depolymerization rate data at 265°C were found to fit a kinetic model proposed earlier for the uncatalysed hydrolysis of PET. The effect of zinc and sodium salts on the activation energy of hydrolysis, or on the formation of ethylene glycol monomer is unclear. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070530801
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  • 7
    Electronic Resource
    Electronic Resource
    Thermolysis of polyethylene/polystyrene mixtures (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 2133-2140 
    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 thermolysis of 60/40 mixtures of polyethylene (PE) and polystyrene (PS) was investigated at temperatures below 440°C. Liquid yield from the mixture, 84.1%, was comparable to yields obtained with the individual polymers. The yields of styrene monomer, 57.1%, and α-olefins, 27.7%, increased over those obtained when the polymers were processed individually. A significant interaction was observed between the polymers in which the addition of PS enhanced the rate of thermolysis of PE. It is proposed that this enhancement was due to the abstraction of hydrogen from the PE fraction by polystyryl radicals. The result of this effect is to increase the rate of volatile production from the PE and increase the solubility of the residue in chloroform. The data also support a mechanism for dimer production other than the generally accepted 1,3 transfer. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    A kinetic study of the hydrolytic degradation of polyethylene terephthalate at high temperatures (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 443-451 
    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 hydrolytic depolymerization of molten PET in excess water was studied using a 2 L stirred pressure reactor at temperatures of 250, 265, and 280°C. Rate constants for hydrolysis are calculated from the initial rate data. At initial water: PET charge ratios (w/w) exceeding 5.1, essentially complete depolymerization to monomer is possible at 265°C. At lower water: PET initial charges, an equilibrium is established. The equilibrium constants are calculated for 2 g water/g PET at three temperatures. A kinetic model is proposed to describe the hydrolysis reaction. The model is shown to fit experimental data and to yield good predictions for the equilibrium concentration of carboxyl groups. Carboxyl-group concentrations are measured using an end-group analysis technique. Potentiometric titrations are carried out in one of two solvent systems, dimethylphenol:chloroform or dimethylsulfoxide, depending on the extent of hydrolysis. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070480309
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