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  • Physics  (74)
  • 1980-1984  (74)
  • 1970-1974
  • 1980  (74)
  • 1
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The plasma polymers formed in glow and nonglow regions of an inductively coupled RF plasma with perfluorobenzene and perfluorocyclohexane are discussed as a function of operating conditions of the plasma by means of ESCA. The core levels of the plasma polymers are shown to be strikingly different but characteristic of a well-defined but complex polymerization scheme. For the nonglow regions fluorine incorporation is shown to be greater than for polymers prepared in the glow regions and a preponderance of CF2 features is apparent. Perfluorobenzene deposits polymer faster than perfluorocyclohexane and changes in component composition of the C1s profile are studied as a function of operating conditions of the gas plasma.
    Additional Material: 13 Ill.
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  • 2
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The plasma polymers prepared from perfluorocyclohexa-1,3-diene, perfluorocyclohexa-1,4-diene, and perfluorocyclohexene have been investigated by ESCA. The carbon-to-fluorine stoichiometries of the diene-derived polymers are similar and close to that of the starting material. The polymer prepared from perfluorocyclohexene is depleted in fluorine compared to the fluorine content of the “monomer.” The polymers prepared in nonglow regions are also studied and shown to be high in CF2 derived species. The results are compared with those for perfluorobenzene and perfluorocyclohexane, and the polymerization rates are in the order C6F6 〉 C6F8 1,3 ∼ 1,4 〉 C6F10 ∼ C6F12. The variations in composition of the plasma polymer as revealed by ESCA as a function of the polymerization conditions are discussed.
    Additional Material: 14 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 3245-3251 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polypropylene (PP) and polyethylene (PE) peroxy radicals undergo photoreactions, but under commonly encountered photodegradation conditions these reaction rates are much lower than those of conventional radical reactions; for example, for PP peroxy radicals in noon summer sunlight at 25°C their rate of photolysis to alkyl radicals is less than one-tenth of their rate of hydrogen abstraction from the polymer. At lower temperatures( 〈 -10°C) or when more intense radiation is used, however, peroxy radical photolysis becomes a proportionately more important source of alkyl radicals. In addition, occurrence of photoinduced radical combination is confirmed but is shown to be important only when photolysis generates an alkyl radical sufficiently close to a peroxy radical that termination can occur before oxygen reconverts the alkyl radical to a peroxy radical. This termination mechanism therefore becomes more important for radicals generated at lower temperatures when the average separation of a radical pair is lower.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 903-911 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An experimental investigation was conducted to relate the average number of radicals per particle, n̄ to the dimensionless parameter α, as suggested by Stockmayer. Seed emulsion polymerizations of polystyrene were run over a wide range of particle sizes and initiator levels in the 50-70°C temperature range. The seed polymerization technique removed the question of particle formation behavior and allowed a straightforward determination of n̄. Alpha was varied more than three orders of magnitude and resulted in measured values of n̄ in the range 0.5-1.3. These data are in good agreement with Stockmayer's relationship as long as the value of the termination rate constant is taken at the monomer/polymer ratios found in emulsion polymerization. For polystyrene at a monomer/polymer ratio of 60/40 this value is an order of magnitude lower than that found for infinitely dilute polystyrene solutions.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 71-82 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In light of novel and problematic diffraction patterns arising through the thermoreversible gelation of isotactic polystyrene, the conformational possibilities were examined with particular reference to other conformational works published recently on this polymer. The specific objective was to ascertain whether highly extended, helical backbone geometries such as are required by the new x-ray patterns are possible or not with a purely isotactic arrangement of side groups. The first realization was that the recently announced low-energy, near-trans conformations are not relevant to the present issue as they do not provide the required extended geometry. Further, specific sampling of the conformational energy map revealed that the required high chain extension may be energetically feasible, contrary to traditional conceptions and to recent conformational calculations elsewhere. The divergences as regards the latter were traced to the specific choice of nonbonded atomic radii - all within generally accepted limits - which accordingly has a crucial effect even to the extent whether specific conformation types are forbidden or energetically stable. The implications this has for conformational analysis in general are being pointed out. While the novel crystal structure has not been solved, the present study at least eliminates the previously believed categoric objections to it being associated with isotactic chains and, beyond this, opens up new perspectives as regards conformational possibilities in polyolefins. The more general problems concerning the nature and origin of the gelation phenomenon nevertheless remain.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 779-791 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectra of 1,6-di-p-methoxybenzene-sulfonyloxy-2,4-hexadiyne (MBS) have been recorded during thermal polymerization. The spectra are similar to those of the related p-toluene-sulfonyloxy monomer but indicate a higher strain in the initially formed MBS polymer chains. Despite this similarity, the polymerization kinetics for the two monomers are markedly different. The polymerization behavior of MBS shows that the polymer chain initiation and propagation are practically independent of lattice strain. Possible causes for this independence are discussed.
    Additional Material: 10 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 2337-2345 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Homogeneous films comprised of mixtures of polystyrene and poly(vinyl methyl ether) can be obtained by evaporation from a ternary solution containing toluene as the solvent. Heterogeneous films result when the solvent is trichloroethylene. The possibility that a heterogeneous film cast from trichloroethylene can be transformed to a homogeneous one by physical means is a logical expectation when the polymer-polymer interaction is favorable, though as yet no comprehensive report has appeared in the literature. We have accomplished the transformation by increasing the temperature. Optical microscopy and glass transition experiments were employed to observe the effects.
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 355-357 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 967-985 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transport of oxygen by diffusion from the environment into a gas stream was investigated as a model for the analogous process in a diffusion flame. The amount transported at steady-state conditions depended on the flow rate, diameter, and spatial orientation of the gas stream. A change of the same extrinsic parameters in a diffusion flame caused changes of burner surface temperature, maximum flame temperature, and flame height. These responses were correlated and yielded an overall activation energy of the rate-controlling reaction step in the combustion process equal to 49 kcal/mole. This value was the same for several types of diffusion flames examined and appeared to be associated with the CO/CO2 conversion process at the high-temperature flame boundary. Flame quenching was demonstrated to occur at a minimum fuel flow rate and minimum environmental oxygen concentration which were characteristic for a given fuel. Quenching conditions were related to the diffusion rate of oxygen into the product effluent stream. Quenching of a polymer flame by depletion of environmental oxygen was governed by the same processes. The effect of extrinsic parameters on polymer flames is discussed in Part II.
    Additional Material: 16 Ill.
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  • 10
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of N-methyl-substituted aromatic polyamides derived from the secondary aromatic diamines 4,4′-bis(methylamino)diphenylmethane, 3,3′-bis(methylamino)diphenylmethane, 4,4′-bis(methylamino)benzophenone or 3,3′-bis(methylamino)benzophenone and isophthaloyl dichloride, and terephthaloyl dichloride or 3,3′-diphenylmethane dicarboxylic acid dichloride was prepared by high-temperature solution polymerization in s-tetrachloroethane. Compared with analogous unsubstituted and partly N-methylated aromatic polyamides, the full N-methylated polyamides exhibited significantly lower glass transition temperatures (Tg), reduced crystallinity, improved thermal stability, and good solubility in chlorinated solvents.
    Additional Material: 3 Ill.
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