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  • 1
    Electronic Resource
    Electronic Resource
    Configurational entropy of polyethylene and other linear polymers (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 4 (1966), S. 869-880 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The configurational entropy of the polyethylene chain at the melting points calculated in two ways. In both calculations, tetrahedral angles and discrete trans and gauche arrangements of all bonds are assumed, and trans bonds are assumed more stable than gauche by energy U1. First, calculations are made on chains of up to N = 18 bonds, disallowing all configurations having overlapping atoms, and the result is extrapolated to large N. Second, a calculation is made directly for long chains, with overlaps excluded only over every short chain segment. The results are in almost exact agreement, suggesting that the second method can be safely used with other molecules. The calculated configurational entropy is in line with that suggested by the entropy of fusion, assuming the chains to acquire a configurational freedom in the melt which approaches that of independent chains.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1966.160040604
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  • 2
    Electronic Resource
    Electronic Resource
    Equation of state and the thermodynamic properties of liquid polymers: Application of the Hirai-Eyring modelPresented at Symposium on Thermodynamic Properties of Bulk Polymers, National Bureau of Standards, Gaithersburg, Md., March 10-12, 1969. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1337-1360 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is shown that the Hirai-Eyring model for the liquid state is capable of accurately describing the p, V, T behavior of liquid polymers in the temperature range over which measurements are now made, and below. Once the parameter choices necessary to accomplish the fit are made for a particular polymer, the excess thermodynamic functions (differences in properties, liquid less solid) are determined by the same parameters. Above the glass transition temperature Tg the volume, excess enthalpy, and square of the excess entropy are predicted by the model to be essentially linear with temperature, in agreement with experiment. Below Tg, these functions do not remain linear (as is usually assumed in extrapolating the equilibrium behavior to low temperatures), but instead they rapidly approach zero in a continuous way as the temperature is lowered. These remarks apply to glass-forming materials composed of small molecules, as well as to polymers. The “paradox” raised by Kauzmann is thus resolved, and the Gibbs-DiMarzio second-order transition appears to be unnecessary.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080807
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  • 3
    Electronic Resource
    Electronic Resource
    Viscoelastic properties of branched polyethylene melts (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 455-465 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical properties of branched polyethylenes in the molten state were determined in the frequency range 10-3-10 radians/sec. The materials tested have remarkably similar rheological properties even though they vary greatly in molecular weight and molecular weight distribution. The similarity in properties is attributed to the influence of long chain branching on the relaxation spectra. A mechanistic argument is proposed to relate the observed behavior to molecular entanglement coupling. The concept of entanglement coupling involving long-chain branching leads to the expectation that the quasi-Newtonian and non-Newtonian viscosities of branched polymers may be either greater or less than those of linear polymers of the same species, which have comparable molecular weights. This is borne out by experiment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080311
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  • 4
    Electronic Resource
    Electronic Resource
    Extensional infrared orientation (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1921-1929 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In evaluating molecular orientation by dynamic infrared techniques, it is shown, subject to certain restrictions, that an extensional mechanism plays an important role in the measured orientation. Dichroic measurements can indicate a change in segmental orientation without any change occurring in the chain axis orientation. Extensional orientation was evaluated for a general helical molecule in terms of singular and coupled vibrational modes. Significant orientation changes can occur by the extensional mechanism, the sign and magnitude of which depend on the components of the transition moment vector.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180141101
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanisms of frequency shifting in the infrared spectrum of stressed polymer (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1795-1808 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the vibrational spectrum of a polymer obtained under tensile stress loading conditions, several modes of molecular deformation can lead to different mechanisms of frequency shifting and asymmetric band deformation. Theoretically and experimentally it has been observed that quasielastic deformations (reduction of force constants due to bond weakening under stress), pure elastic bond stretching and angle bending, conformational variations, and several types of chain defects can cause linear shifts in frequency and infrared band distortion. A detailed study of the deformation spectra of isotactic polypropylene and polyphenyl-p-sulfide indicated that quasielastic and elastic mechanisms are the major contributors to frequency shifting, principally affecting stretching and bending vibrational modes. Conformational mechanisms can affect torsional modes whereas the defect mechanism, when present, can cause random distortion of an infrared band. The latter mechanism is difficult to quantize. The extent to which each mechanism contributes to the total spectral deformation can be a function of morphology, macroscopic loading conditions, thermal and strain histories.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130912
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  • 6
    Electronic Resource
    Electronic Resource
    Morphological mechanics of springy polymers (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 603-618 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanics of “springy” or “hard elastic” row-crystallized polymers were investigated. It was found that their unique tensile and physical properties could be explained by adhesive fracture mechanics and simple beam deflection. The deformed lamellae had an apparent negligible modulus of flexural rigidity. An adhesive failure model was designed which duplicated all the tensile characteristics of springy polymers, including constant lateral contraction, critical stress, peel stress, rehealing, energetic elasticity, and cyclic strain behavior. The ideal relative density change as a function of strain was found to be the same for all springy polymers. Dynamic infrared analysis showed that the molecular orientation decreased during the deformation of springy polypropylene films. The latter is due to the deflection of lamellae. Rehealing was accompanied by a time-dependent reversal of orientation. The enthalpic elasticity is derived from the strain energy of the lamellar network.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140403
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  • 7
    Electronic Resource
    Electronic Resource
    Alkylated polypyrazines (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 10 (1972), S. 2919-2923 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of four new monomers and two new polyaromatic pyrazines are described. The monomers; bis-p,p′-(octanoyl)diphenyl ether (Ia), bis-p,p′-(hexadecanoyl)diphenyl ether (Ib), bis-p,p′-(α-bromooctanoyl)diphenyl ether (IIa), and bis-p,p′-(α-bromohexadecanoyl)diphenyl ether (IIb), were produced by Friedel-Crafts acylation of diphenyl ether with the corresponding acyl chloride and subsequent α-bromination. Prepolymers were synthesized by the condensation of (IIa) and (IIb) with ammonia in N,N-dimethylformamide (DMF), and polymers were prepared by subsequent melt condensation of the prepolymer to produce poly[2,5-(oxydiphenylene)-3,6-(dihexyl)pyrazine] (IIIa), and poly[2,5-(oxydiphenylene)-3,6-(ditetradecyl)pyrazine] (IIIb). Polymer IIIa was thermally (stable at 〉400°C while polymer IIIb was a tacky substance). The inherent viscosity of IIIa produced by 12 hr of melt condensation was 0.30 dl/g in formic acid. Additional heating in excess of 24 hr gave a slightly soluble polymer. The inherent viscosity of IIIb produced by 40 hr of melt condensation was 0.37 dl/g in formic acid.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.170101010
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