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  • Chemistry  (12)
  • INSTRUMENTATION AND PHOTOGRAPHY  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Rates of molecular vaporization of organic plasticizersBased on Research Supported by the Advanced Research Project Agency, Washington, D. C. 20301 (1970)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 10 (1970), S. 19-23 
    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 kinetics of the molecular vaporization process of 21 plasticizers were investigated in detail. By both isothermal and nonisothermal kinetic methods, it was evident that 11 were quite pure single compounds, while 10 were clearly mixtures of compounds. For the single component species internal energies for vaporization and rates of volatilization are listed. The internal energies of vaporization are about one-half or less of values one can estimate from the additive factor method of Small. Thus, solubility parameters based on our experimental values are low by about 30 percent. From this and previous work on linear alkanes, it is concluded that in the molecular vaporization process, the large organic molecules studied evaporate approximately as spheres and hence low values for the energy of vaporization are obtained. Consequently, the difference between our experimental energy and that estimated from solubility parameters is the energy for extending the molecule in a vacuum environment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760100105
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  • 2
    Electronic Resource
    Electronic Resource
    Liquid (melt) heat capacities and heats of vaporization of oligomers of poly(hexamethylene sebacate) (1975)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 73-78 
    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 liquid heat capacities and heats of vaporization of three linear esters of poly(hexamethylene sebacate) with hexylcapped end groups (M(mol. wt.) = 370, 655, and 939) have been determined. The heats of vaporization of the oligomers measured at a mean temperature were corrected to 323.15 to 523.15°K by use of the experimental liquid (melt) heat capacities and the calculated gas heat capacities. The corrected heats of vaporization were fitted to the equation ΔHv = S(T)Mα + I(T), where the temperature dependence of the slope and intercept are represented, respectively, as S(T) = ClnT + Ko and I(T) = a T + bo, and α is an exponent. The results indicate (at corresponding molecular weights and constant temperature) that the ratio of the liquid heat capacities of the oligomer ester and the n-alkane, and similarly the ratio of the heats of vaporization, depend on the number of carboxyl groups in the oligomer ester chain.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760150204
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  • 3
    Electronic Resource
    Electronic Resource
    Pyrolysis of new fluoropolymersBased on research supported by the Bureau of Naval Weapons, Department of the Navy and the National Aeronautics and Space Administration. Presented in part before the Polymer Chemistry Division at the 142nd Meeting of the American Chemical Society, Atlantic City, New Jersey, September 14, 1962. (1964)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 4 (1964), S. 56-60 
    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: Four new fluoropolymers were pyrolyzed in a vacuum to study rates of volatilization and to identify decomposition products. The polymers thus studied were polyperfluoropropylene, polyperfluoroheptene, poly-4-chloroperfluoroheptadiene-1,6 and poly (1,2,2-triflluorovinyl phenyl ether). Polyperfluoropropylene yielded 100% monomer at temperatures of 300 to 400°C gave an activation energy of 56.6 Kcal/mole. Polyperfluoroheptenes of different molecular weights also yielded 100% monomer on heating. However, they had lower thermal stability than polyperfluoropropylene, but a higher activation energy and a higher pre-exponential factor. Poly-4-chloroperfluoroheptadiene volatilized at a rate of approximately 1% per minute at 380°C. There was very little monomer produced on thermal decomposition and an activation energy of 60 Kcal/mole was obtained from rates of volatilization at 362, 374, and 381°C. Poly (trifluorovinyl phenyl ether) showed a 25% carbonized residue at 500°C pyrolysis. The polymer decomposes into fragments containing very little monomer. Undesirable low molecular weight components in the polymer are still to be eliminated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760040112
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  • 4
    Electronic Resource
    Electronic Resource
    Pyrolysis of polytrifluoroethylene: Influence of gamma radiation and alkali treatmentBased on research supported by the National Aeronautics and Space Administration. Presented in part before the American Chemical Society, Atlantic City, New Jersey, September 14, 1962. (1964)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 4 (1964), S. 61-65 
    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: Pyrolysis in vacuum of gamma-irradiated polytrifluoroethylene indicates increased rates of volatilization with increased dosage. At the higher radiation doses, the rate curves no longer show a maximum but resemble those previously obtained with branched polyethylenes. Studies of swelling with acetone indicate crosslinking increases with radiation dose. It is estimated that for each chain fracture caused by radiation there are approximately seven crosslinks formed. However, in addition to the crosslinks a branched structure is also being produced as evidenced by the character of the thermal degradation rate curves. Alkali treatment of the polymer sensitizes it towards dehydrofluorination and double bond formation. Subsequent rate and pyrolysis studies showed the formation of very stable residues, indicating a relatively greater thermal stability of the main chain.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760040113
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  • 5
    Electronic Resource
    Electronic Resource
    High-pressure polymerization induced by gamma radiation (1962)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 2 (1962), S. 117-118 
    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
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760020218
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  • 6
    Electronic Resource
    Electronic Resource
    Gamma irradiation of polytetrafluoroethylene in chlorineBased on research supported by the Aeronautical Research Laboratory, United States Air Force, Wright-Patterson Air Force Base, Ohio. Presented in part before the American Chemical Society, Atlantic City, New Jersey, September 14, 1962. (1963)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 3 (1963), S. 290-299 
    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: Films of polytetrafluoroethylene, irradiated in halogen atmospheres, decrease in ultimate tensile strength and elongation at break almost as rapidly as in oxygen. The rate of degradation is approximately independent of chlorine pressure down to about 1 mm Hg. The phenomena can be explained semi-quantitatively in terms of first order, cage reactions of scission, recombination, and reaction with chlorine, complicated by diffusion at low pressures. However, all reaction and diffusion parameters must shift with gradual increase of crystallinity.For a given decrease of elongation at break, polytetrafluoroethylene irradiated in a vacuum retains a relatively higher ultimate tensile strength. In the copolymer of tetrafluoroethylene and hexafluoropropylene, the changes in ultimate tensile strength and elongation at break are much slower under all conditions. Both polytetrafluoroethylene and the copolymer retain appreciable tensile strength but little elongation up to a dose of 2 x 108r.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760030409
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  • 7
    Electronic Resource
    Electronic Resource
    Depolymerization as a chain reaction (1950)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 5 (1950), S. 615-632 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1950.120050509
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  • 8
    Electronic Resource
    Electronic Resource
    Pyrolysis of α- and β-deuterostyrene polymers (1955)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 15 (1955), S. 157-166 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recently the depolymerization of addition polymers has been treated in terms of four elementary reactions: initiation, propagation, transfer, and termination; analogous to those reactions which operate in the polymerization process. It is the transfer process which, according to its relative importance, gives rise to differences in polymers in the monomer yield, in the rate vs. conversion behavior, and in the molecular weight vs. conversion behavior. The transfer process is assumed to operate through the abstraction of a hydrogen from the polymer chain by a radical. By substituting a deuterium for the hydrogen at selected points in the polymer chain, the amount of the transfer process should be decreased due to an isotope effect. Two deuterated polymers were made from α- and β-deuterated styrenes and their depolymerization behavior studied. In the case of the α-deuterostyrene polymer the results are compatible with a ½ decrease in the rate of the transfer process and also an increase in the rate of the propagation. The results with the β-polymer imply an increase in both the transfer and propagation rates. The data obtained indicate that in polystyrene the intermolecular transfer process is mainly responsible for the fall in molecular weight of the polymer residue during depolymerization.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1955.120157913
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  • 9
    Electronic Resource
    Electronic Resource
    Some aspects of depolymerization kinetics (1951)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 6 (1951), S. 39-44 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A brief discussion of the importance of the transfer step and its effect in the pyrolysis of polyethylene is given. In this case the removal, by molecular distillation, of smaller species from the reacting mixture modifies the kinetics. The molecular weight decreases less rapidly and tends to a limiting value depending on the maximum size of the evaporating molecules. The number distribution of the latter is, in a first approximation, independent of their size. The pertinent expressions are presented and the general solution of the rate equations which can be used to obtain higher approximations is given.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1951.120060107
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  • 10
    Electronic Resource
    Electronic Resource
    Study of degradation of polystyrene by means of mass spectrometryPresented at the International Congress of Pure and Applied Chemistry, New York, September, 1951. (1952)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 8 (1952), S. 555-571 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The degradation of polystyrene by heat and ultraviolet radiant energy was followed by mass spectrometric analysis of the gaseous products evolved. Oxygen content, discoloration, and insolubility of the treated polymer were also investigated. The degradation of polystyrene involves two different processes: (1) the breakdown of thermolabile groups formed in the polymer prior to degradative treatment; this breakdown is caused by exposure to heat at 120°C. in vacuo and 115°C. in oxygen and to ultraviolet radiant energy at 120°C. in vacuo and 118°C. in oxygen; it is accompanied by the removal of residual materials such as solvent; and (2) the oxidation of the polymer caused by exposure to ultraviolet radiant energy in the presence of oxygen. The evolution of benzene, methyl ethyl ketone, dimethylbenzenes, and alcohols is associated with the first stage involving the breakdown of thermolabile groups and the removal of residual materials. Compounds such as formaldehyde, formic acid, and acetic acid are produced as a result of oxidation of the polymer. The oxygen content of the polymer was decreased from 0.33 to approximately 0.1 percent by heating at 120°C. in vacuo and at 115°C. in oxygen, and by exposure to ultraviolet radiant energy at 120°C. in vacuo. Ultraviolet treatment at 118°C. in oxygen for 250 hours quadrupled the original oxygen concentration. Discoloration of the polystyrene was definitely noted only on exposure to ultraviolet radiant energy in oxygen and is associated with oxidation of the polymer. The material became insoluble as a result of all heat and ultraviolet treatments. The amount of insoluble material increased with severity of exposure conditions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1952.120080513
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