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  • Inorganic Chemistry  (830)
  • Physics  (430)
  • 1965-1969  (1,260)
  • 1967  (1,260)
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  • 1965-1969  (1,260)
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  • 1
    Unknown
    New York : Academic Press
    Keywords: DDC 515/.353 ; LC QA371 ; Differential equations, Partial ; Physics
    Pages: Online-Ressource (xi, 335 pages)
    ISBN: 9780126546569
    Language: English
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1327-1328 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 23-35 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyacrylamide having a fluorescent residue at the chain end was prepared by polymerization of acrylamide in the presence of a fluorescent dye. The segmental motion of the chain end in dilute solution was studied by the fluorescence polarization method on the fluorescent polyacrylamide conjugates thus obtained. The linear relation between 1/p and T/η0 held for every sample studied in aqueous media, where p is the degree of polarization of the fluorescence, T is the absolute temperature, and η0 is the viscosity of the medium. The mean relaxation time 〈ρ〉 of the conjugate was evaluated from these data as a function of the molecular weight of the conjugate. The value of 〈ρ〉 increased slightly with molecular weight, varying from 3.3 × 10-9 to 7 × 10-9 sec. The absolute values of 〈ρ〉 and its molecular weight dependence suggest that 〈ρ〉 represents the mean rotational relaxation time for the cooperative motion of about ten monomeric units at the chain end. The effect of the mean extension of polymer chain on the segmental motion was found to be negligible.
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  • 4
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 37-45 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fluorescence polarization method has been used to study the micro-Brownian motion of a terminal segement of a polymer chain in concentrated solutions. A new apparatus for determining the fluorescence intensity and its polarization degree was designed. By using this apparatus, the rotational relaxation time 〈ρ〉 of the terminal segment of the fluorescent conjugates of polyacrylamide in aqueous polyacrylamide solutions was obtained as a function of polymer concentration from 0 to 65%, molecular weight of the conjugate from 3.5 × 104 to 3 × 105, and temperature from 10 to 30°C. The logarithm of 〈ρ〉 increased approximately linearly with increasing polymer concentration. This increase in 〈ρ〉, amounting to a factor of 20 times, was less marked than that in macroscopic viscosity. At concentrations less than 30%, 〈ρ〉 depended appreciably on the molecular weight of the conjugate.
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  • 5
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 47-61 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyethylene networks were prepared by γ-irradiation of linear polyethylene, both molten and crystalline. The elastic and photoelastic properties of the networks were studied at high temperatures, i.e., in the molten state. The equilibrium swelling was also measured in several solvents. Values of the crosslinking efficiency G of γ-radiation, the molecular, weight Me between entanglements, the optical anisotropy α of the equivalent random link, and the polymer-solvent interaction parameter μ are deduced. Samples prepared by irradiation in the amorphous state showed markedly non-Gaussian elastic behavior. The presence of a large non-Gaussian term in the optical anisotropy is also deduced. The value of α obtained for swollen samples, which showed substantially Gaussian elastic behavior, was 3.9 × 10-24 cm.3, about one-half of that obtained for dry samples. It corresponds to an equivalent random link of only about 5 CH2 units, on the basis of Denbigh's values for bond polarizabilities. The samples prepared by irradiation in the crystalline state showed lower values for α, which also depended upon the degree of crosslinking. This is attributed to the nonrandom chain configurations prevailing at the time of crosslinking. The same samples were found to show more nearly Gaussian elastic behavior, which is attributed to the same cause.
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  • 6
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 63-81 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Detailed structure analysis of the polyoxymethylene molecule was carried out by the method of three-dimensional Fourier synthesis. The diffraction data were measured on a highly ordered polyoxymethylene sample prepared from a single crystal of tetraoxane by solid-state radiation polymerization. By assuming the anisotropic thermal factors for the oxygen and carbon atoms and taking into account the contribution of the hydrogen atoms, good agreement between the observed and calculated structure factors was obtained; the R factor is 8.8%. The distance between the oxygen atom and the helix axis r(O) = 0.671 A. is slightly shorter than r(C) = 0.691 A. The bond distance C—O = 1.421 A., the angle ∠COC = 112°24′, and ∠OCO = 110°49′. All the internal rotation angles of the skeletal bonds are 78°13′. It is deduced from the experimental results that each crystallite of polyoxymethylene is composed of only one type of helix, right-handed or left-handed.
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  • 7
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 83-87 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relation of the high-frequency elastic moduli of semicrystalline polymers to volume fraction crystallinity is correctly described by the Hashin-Shtrikman theory, without any disposable constants, as a function of the ratio of the modulus of the amorphous to that of the crystalline phase. Hence the (high-frequency) reduced modulus of semicrystalline polymers is largely a function of the temperature T/Tg. The importance of T/Tm for the modulus of the crystalline phase precludes the existence of a single universal reduced modulus versus temperature curve.
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  • 8
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 239-262 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The infrared absorption spectra of selected crystalline and noncrystalline bands were studied in bulk-crystallized specimens of linear polyethylene which encompassed the extremely wide density range of 0.92-0.99 g./cm.3. The analysis of the data obtained at room temperature yield degrees of crystallinity by infrared methods which are in very good accord with the values deduced from the density measurements. Studies of the infrared spectra as a function of temperature give fusion curves which are in agreement with those obtained by thermodynamic methods. However, in order to obtain these latter results cognizance must be taken of the large negative temperature coefficient of the specific extinction coefficients of the crystalline bands from room temperature to the melting point. The necessary data to account for this phenomena were obtained from studies of the spectra of the n-paraffin, C94H190, where molecular crystals are formed. Analysis of the two gauche bands, at 1352 and 1303 cm.-1, which are assigned to the noncrystalline regions demonstrate that for bulk-crystallized samples of lowest densities the intensity ratio at room temperature is identical to that expected from the pure melt at this temperature. The conclusion is thus reached that the noncrystalline regions in these cases and the pure melt are structurally very similar. For samples of higher density, where the crystallite size is comparable to the extended chain length, the intensity ratio of the two gauche bands is altered. This change could reflect a change in the sequential distribution of gauche bonds. This intensity ratio for crystals formed from dilute solution is very similar to that for the high-density bulk-crystallized material and indicates a similarity in structure of the noncrystalline regions in the two cases.
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  • 9
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 277-288 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To investigate the solution properties of polyethylene, which has the simplest structure of the vinyl polymers, experiments were made with a magnetically suspended equilibrium ultracentrifuge. Preliminary studies were carried out with a polystyrene-chloroform system at 25°C. and a polystyrene-methylcyclohexane system at 68°C. (which is close to the theta temperature) in order to check the difficulties involved in the flotation equilibrium in the former case and the high temperature measurement in the latter. However, no trouble was encountered in either system, and the results were discussed and compared with earlier results for polystyrene solutions. It was found that chloroform is a good solvent for polystyrene, and the measured weight-average molecular weight is somewhat smaller than the value obtained in a theta solvent. After overcoming some technical difficulties involved in studies at higher temperatures, we carried out experiments on polyethylene in α-chloronaphthalene at 130°C. The results are considered reasonable by comparison with results obtained by other methods. The sample employed, Marlex 50 of melt index 0.7, has a wide molecular weight distribution: i.e., Mz/Mw = 5.2 and Mz+1/Mz = 2.4.
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  • 10
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 289-300 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Accurate measurements of stress relaxation after steady-state flow have been carried out, in the Newtonian flow region, for a polystyrene and a poly(methyl methacrylate) melt, with a cone-and-plate rotational rheometer. From the stress relaxation σ(t) versus t curves the relaxation spectra H were calculated by means of the first approximation equation: \documentclass{article}\pagestyle{empty}\begin{document}$ H = - ({1 \mathord{\left/ {\vphantom {1 {\dot \gamma t)d\sigma {{(t)} \mathord{\left/ {\vphantom {{(t)} d}} \right. \kern-\nulldelimiterspace} d}}}} \right. \kern-\nulldelimiterspace} {\dot \gamma t)d\sigma {{(t)} \mathord{\left/ {\vphantom {{(t)} d}} \right. \kern-\nulldelimiterspace} d}}}\ln t $\end{document}. The shear stress-shear rate curves, σ versus \documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma } $\end{document} were also measured, in large ranges of shear rates, for the same melts, and from these data the relaxation spectra H were obtained by means of equations given by Faucher and Ferry. The Faucher equation, \documentclass{article}\pagestyle{empty}\begin{document}$ H = - \dot \gamma ^2 d{\sigma \mathord{\left/ {\vphantom {\sigma d}} \right. \kern-\nulldelimiterspace} d}\dot \gamma ^2 $\end{document}, has been found to give results which compare satisfactorily with those obtained from the first approximation equation. It has been found that the Ferry equation has to be modified for comparable agreement.
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  • 11
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 315-322 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of polydispersity on liquid-liquid phase equilibrium in systems containing polymer, solvent, and nonsolvent is investigated numerically in the Flory-Huggins approximation for several special cases. The resulting phase diagrams indicate that, except in the immediate vicinity of the critical region, the degree of swelling of a polymer precipitate phase with a given number-average molecular weight is essentially independent of polydispersity.
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  • 12
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 399-415 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The statistical mechanical treatment of polymeric chains in terms of the largest eigenvalue of the product of statistical weight matrices for the rotational interactions of skeletal bonds of the repeat unit becomes excessively complicated if the repeat unit spans more than three or four skeletal bonds. Moreover, such treatment is necessarily limited to chains in which the number of repeat units is indefinitely large. Newer methods are readily applicable to chains of any degree of polymerization comprising repeat units of any realizable length. If interdependence of neighboring bond rotations is confined to bond pairs within a given unit, rotations about a pair of bonds belonging to neighboring units being mutually independent, further simplifications may be introduced without sacrifice of rigor. Polyamides, in which rotation about bonds on opposite sides of the amide group are independent, are polymers of this type. Adherence of the amide group to the planar trans conformation favors a more extended configuration of the chain, but this effect is dominated by the smaller steric repulsions affecting rotations about bonds which are first, second, and third neighbors of the amide group. It is for this reason that the characteristic ratio 〈r2〉0〉/nl2 for poly(hexamethylene adipamide), ca. 6.0 according to experimental results of Saunders, is less than the value, 8.0, for polymethylene at 25°C. The characteristic ratios and molecular dipole moments are computed as functions of the degree of polymerization. The poly(εaminocaproamide) chain also is treated.
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  • 13
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    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 461-470 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Proceeding from the work of Zimm and Stockmayer and of Benoit, a general formula is derived for the calculation of the radius of gyration of block and graft copolymers. It appears that with linear block copolymers the ratio of the mean-square radius of gyration and the mean-square end-to-end distance is usually not far from 1/6. With a great number of blocks the difference from 1/6 can entirely be neglected. Also the influence of the composition of the molecules on the scattered light intensity has been considered.
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  • 14
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 639-652 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The primary reaction of oxygen with irradiated polyethylene has been followed by observing the rapid disappearance of the ultraviolet absorption bands at 258 and 285 mμ, bands attributed to the allyl and dienyl free radicals. A mathematical theory based on diffusion equations has been developed by means of which a quantitative estimate of the total initial free-radical concentration can be made. From the shape of the free-radical decay curve it can be concluded that the initial oxygen-free-radical reactions occur about three times as frequently in the amorphous regions as in the crystalline.
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  • 15
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 653-662 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aromatic poly(amic acids) derived from pyromellitic dianhydride and 4,4′,-diaminodiphenyl ether were characterized by dilute solution techniques. Number-average molecular weights M̄n of 13 samples ranged from 13,000 to 55,000 (DP 31-131). Weight-average molecular weights M̄w of 21 samples ranged from 9,900 to 266,000. The ratio M̄w/M̄n was between 2.2 and 4.8. Heterogeneous polymerization yielded higher molecular weight polymer than homogeneous polymerization. The molecular weight could be varied systematically by control of stoichiometric imbalance. Use of very pure monomers and solvent gave polymers of relatively high number-average molecular weight (∼50, 000) and the most probable molecular weight distribution M̄w/M̄n = 2. Impure monomers and/or solvent resulted in lower number-average molecular weight (M̄n ≅ 20,000-30,000) and wider distributions (M̄w/M̄n = 3-5). The Mark-Houwink relation obtained was [η] = 1.85 × 10-4M̄w0.80 The exponent is characteristic of moderately extended solvated coils. The unperturbed chain dimensions (r02/M)1/2 were 0.848 A., and the steric factor σ was 1.24 which is close to the limiting value of unity for an equivalent chain with free internal rotations. The sedimentation constant-molecular weight relation was S0 = 2.70 × 10-2M̄w0.39. This exponent is consistent with the Mark-Houwink exponent.
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  • 16
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 705-710 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recent precision measurements of the heats of combustion of atactic and isotactic polystyrene permit an unequivocal calculation of the enthalpy difference in the bulk amorphous forms of the two isomers of this polymer. Contributions to this quantity arise mainly from the differences in nonbonded interactions in the two configurations but may also contain terms relating to higher energy conformations and to intermolecular interactions. The thermochemical and NMR data of specific polymers and of simple molecules are discussed in a comparison with model compound calculations. The thermochemical method has potentially important applications in studying molecular interactions in stereoregular polymers.
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  • 17
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Tian-Calvet microcalorimeter has been used to measure the heat of solution of atactic polystyrene in toluene at 30°C. By using a special technique for polymer sample preparation, it has been possible to measure directly the difference in conformational energy of the polystyrene chain at different temperatures, from 30 to 100°C. and to calculate its contribution to the specific heat.
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  • 18
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 761-769 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The α, β, and γ transitions at temperatures between -200 and +100°C. of crosslinked aromatic and aliphatic epoxy polymers were determined from damping and shear modulus data, and compared with their fluorine containing analogs. Loci of segmental relaxation are suggested at various temperatures, and similarities between aliphatic and fluorocarbon segments, and polyethylene and polytetrafluoroethylene are discussed. Two systems of structurally similar monomers 2,2,3,3,4,4-hexafluoropentane diglycidyl ether-1,5 and 1,4-butane diglycidyl ether, and 2,2-bis(4-glycidyl phenyl ether)hexafluoropropane and 2,2-bis(4-glycidyl phenyl ether) propane were polymerized with the aid of two diamine curing agents, namely, ethylenediamine and m-xylylenediamine. Polymers of the aromatic diepoxides showed transitions with peaks at -56°C. and above +70°C. Three main peaks were registered for the aliphatic and fluorocarbon diepoxides: at -125 and at -100°C., at -56°C., and at 0°C. It is suggested that the Tg is affected by an interdependence of relaxation of all components of the polymer main chain.
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  • 19
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1313-1316 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 20
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. i 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 21
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1-21 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Light-scattering, viscometric and osmometric studies have been carried out on dilute solutions of polycarbonate fractions both in a good solvent and in theta solvents. The data span the molecular weight interval 5 〈 10-3M 〈 760. It has been concluded that: (1) the overall behavior in dilute solution is consistent with a flexible chain conformation; (2) the ratio of the unperturbed mean-square radius to the molecular weight, or to the number of chain elements, is larger than commonly observed for vinyl polymers; (3) the ratio of the unperturbed radius to the radius calculated for a chain with free rotation about valence bonds has the unusually small value 1.3; and (4) the hydrodynamic behavior of the chain may reflect partical draining affects.
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  • 22
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 125-142 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Degradation of poly(ethylene oxide) (PEO) by violent stirring was studied in various solvents. The chain scission or the limit of the degradation was measured, and the effects of solvents, polymer concentration, stirring speed and degree of polymerization (DP) were investigated. It was found that the number of bonds broken per polymer chain was independent of the concentration but increased with the stirring speed and with decrease in the DP. The rate was much affected by the solvent used, being larger in a poor solvent. It was also found that the rate could be represented either by Jellinek's or Ovenall's rate equations, which have been applied to the ultrasonic degradation of polymers in solution.
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  • 23
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 165-177 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal expansion and dielectric relaxation of polyacrylonitrile were measured in the temperature range from -75 to 152°C. at frequencies from 30 cps to 3 Mc./sec. The thermal expansion curve and the temperature dependence of logarithmic relaxation time both show an inflection at 85°C. An x-ray study by Bohn reveals that this inflection comes from the thermal expansion of the paracrystalline phase of this polymer, and consequently the transition at 85°C. and the associated relaxation are ascribed to molecular motion in the paracrystalline phase. The relaxation strength increases with increasing temperature above this point. The transition is caused by freezing of the bending vibration of chains whereas the relaxation results from rotational vibration. The length of segments in this phase is roughly estimated to be ca. 100 A. by comparing the observed relaxation strength with the theory developed on the basis of the above considerations.
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  • 24
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 179-193 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to explain the observed nonvanishing limiting value of dynamic intrinsic viscosity of polymer solutions at ω = ∞ one has considered the necklace model with finite resistance to the rate of coil deformation introduced long ago by Cerf for the study of gradient dependence of intrinsic viscosity and streaming birefringence. The calculation need not take into account change of hydrodynamic interaction as a consequence of coil deformation because the experimental data are always either obtained at very low gradient or extrapolated to zero gradient so that in the experiment the macromolecule has the same conformation as in the solution at rest. The model indeed yields a finite [η]′ω = ∞ in good agreement with experiments on polystyrene in Aroclor. According to the theory [η]′ω = ∞/[η]0 decreases with increasing molecular weight as M-1 and M-1/2 for the free-draining and impermeable coil, respectively. The absolute limiting value [η]∞′, therefore turns out to be nearly independent of M, at least for small values of internal viscosity. From the observed value [η]∞′/[η0] one can obtain the coefficient of internal viscosity of the macromolecule. The value for polystyrene in Aroclor calculated from dynamic experiments on rather concentrated solutions is close to that derived by Cerf from streaming birefringence observations of polystyrene in a series of solvents of widely differing viscosity.
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  • 25
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 225-229 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 26
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 301-313 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polarized infrared measurements were made on polymer samples to obtain the structural changes occurring during the orientation process. The absorbances of the infrared bands were measured by determining the three components of the absorbance. Two components were obtained directly with plane-polarized light while the third is obtained by tilting the sample and extrapolating. Corrections were made for machine optics polarization, sample birefringence, polarizer inefficiency, anisotropy of the index of refraction, and scattering from the film surface. Data are reported for polyethylene obtained from cold-drawn specimens as a function of draw temperature. Polyethylene exhibits no strain-induced crystallization as a result of the chain-alignment process. Annealing of the drawn samples reperfects the distorted crystals.
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  • 27
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 323-331 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The diffusion coefficient of 1,1,2-trichlorotrifluoroethane (TTE) in a liquid polybutene was determined at 25°C. as a function of concentration over the range 1.0-19.5 g. TTE/100 cc. The diffusion coefficient increase with increasing TTE concentration, rising continuously from 3 × 10-8 cm.2/sec. at the lowest concentration to 15 × 10-8 cm.2/sec. at the highest. The magnitudes of the diffusion coefficients indicate that the diffusion mechanism for small molecules in polymeric media must afford vastly greater opportunities for diffusion than the Stokes-Einstein relation allows. Similarly, self-diffusion coefficients for the liquid polymer are much lower than the observed mutual diffusion coefficients. An explanation for this behavior is presented.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 333-342 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of long-chain branching must be considered in gel permeation chromatography to evaluate the molecular weight polydispersity of branched polyethylenes. Osmotic molecular weights of fractions of branched polyethylene were correlated with elution volumes; weight-average and number-average molecular weights of a branched polyethylene were determined. Molecular weight changes on crosslinking polyethylene by ionizing radiation are accompanied by branching and cannot be simply interpreted by gel permeation chromatography.
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  • 29
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 343-360 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results of detailed measurements of osmotic pressure, light scattering, and viscosity of poly(vinyl chloride) solutions are used to establish the molecular weight dependence of [η] and A2, to estimate the unperturbed dimensions of the poly(vinyl chloride) molecule, and to analyze critically the [η]-M correlations published hitherto.
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  • 30
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 391-393 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 31
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 555-568 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple differential, isothermal calorimeter has been built to study the thermodynamics of interactions associated with a variety of polymer solution processes. The calorimeter is readily operated at temperatures ranging from ambient to about 200°C., temperature adjustments are rapid, and the apparatus is rugged enough to permit application to commercial process studies. Though less sensitive than microcalorimeters, it represents an attractive combination of satisfactory accuracy, speed, and flexibility of operation. The operation of the calorimeter is demonstrated by measurements of the heat of solution of sodium chloride in water and the heats of solution of various polyolefins in Tetralin and α-chloronaphthalene. The latter tend to confirm the presence of polymer aggregates in chloronaphthalene solutions below the thermodynamic melting temperature of the polymer.
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  • 32
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 583-596 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The optical and mechanical properties of poly(vinyl chloride) film were examined by observing both the stress and birefringence during stretching at constant rate, during relaxation at constant length and during a dynamic birefringence experiment. Experiments were also done by varying the temperature at constant length. The changes in birefringence are interpreted in terms of changes in negative distortional birefringence, changes in positive orientation birefringence, and possible reversible changes in birefringence with temperature arising from conformational changes in the polymer chain and changes in the contribution of birefringent crystals.
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  • 33
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 597-613 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dependence of crystalline morphology of isotactic polypropylene crystallized from dilute solutions on its molecular weight and growing conditions and the mechanism of crystal growth were studied by electron microscopy and electron diffraction. Lathshaped lamellar crystals 150-300 A. in thickness are obtained from fractionated polypropylene powders of Mw (average molecular weight) = 600,000 and 240,000, but not from the samples of Mw = 82,000 and 44,000, by means of isothermal crystallization at 130°C. for 20 hr. in dilute α-chloronaphthalene solution (0.005 wt.-%). Precipitation of the fractionated polypropylene sample of Mw = 82,000 from a dilute solution of carbitol gives typical dendritic crystals under the same isothermal crystallizing conditions as mentioned above. The mode of chain folding in these crystals based on the orientation and the crystal structure of the lamellar crystals agrees with that proposed by Sauer, Morrow, and Richardson. From the morphological observations, the mechanism of growth pertinent to polypropylene lamellar crystals is presumed to be as follows: fibrils at first aggregate, then the molecular chains are folded to form small lamellae, and then these small lamellae accumulate compactly to grow to large, lath-shaped, lamellar crystals.
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  • 34
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 795-798 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 35
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 799-816 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The concentration of solvent in the gel phase of a swelling polystyrene-divinylbenzene copolymer bead has been measured as a function of the radius by optical interference techniques. It is found that an appreciable gradient exists even shortly after the core disappears. Results are presented for two cases: a very lightly crosslinked bead that exhibits negligible birefringence while swelling, and a more tightly crosslinked network in which the birefringence must be considered. It is also found that the refractive index of the unswollen bead is considerably less than that found by extrapolation from the swollen state; this effect is reasonable when the “free volume” in the bulk polymer is considered.
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  • 36
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 817-828 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dispersion of birefringence in oriented amorphous polymers is discussed. It is shown that for polystyrene, the birefringence can be considered as the product of an orientation function and a function of the wavelength of the light. This leads to a method for expressing the birefringence dispersion as a function that is characteristic of the polymer. This function is determined for polystyrene, and from it the birefringence at infinite wavelength is found to be 11% lower than that measured with the mercury green line (5461 A.).
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  • 37
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 829-838 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular dimensions of polydipropylsiloxamer were studied by intrinsic viscosity measurements in toluene and in 2-pentanone. The relationships between the molecualr weight and the intrinsic viscosity were found to be: [η]25°C., toluene = 4.35 × 10-4 M0.58; [η]θ(10°C.), toluene = 1.09 × 10-3 M0.5; [η]θ(76°C.), 2-pentanone = 8.71 × 10-4 M0.5. This held reasonably well for molecular weights from 25,000 to 3000,000. The root-mean-square end-to-end length ratio, (r02/M)1/2 as calculated from the constant K, exceeds the free rotation value by approximately 100%. The disparity is greater than that found with polydimethylsiloxamer, indicating a lower degree of flexibility for the polydipropylsiloxamer. This is largely due to the short range steric interaction between near neighboring units of the chain. Gel permeation chromatography was also employed to demonstrate the lower degree of flexibility for polydipropylsiloxamer as compared with polydimethylsiloxamer.
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  • 38
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 839-852 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The present study is concerned with some network properties of polyurethane elastomers in which stability is acheived via physical crosslinkages such as microcrystallites or secondary bonding. The techniques of isothermal, thermo-, and photoelasticity have been used to gain better insight into the mechanisms which occur during the deformation of these materials. It was found that stable networks are obtained only after mechanical and thermal conditioning. The well-known stress lowering which is observed during the second deformation is manifested primarily in the entropy component of the retractive force. This implies that the stress lowering results from a reduction in the number of effective network chains and not from time-dependent effects or crystallinity changes. Depending upon the chemical structure of the material, both positive and negative energy components of the force have been found.
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  • 39
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 875-889 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: An extension of the results of a previous to higher molecular weights is made. The viscoelastic parameters ηt, Je, τm, and Em are found experimentally through stress relaxation tests. The predictions of the Rouse-Bueche (RB) theory and its modified Ferry, Landel, Williams (FLW) form concerning the molecular weight dependencies of these perameters are compared with the data. It is found that the RB and FLW predictions are not rigorously obeyed.
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  • 40
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 891-898 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Living polystyrene was grafted on fractions of poly(methyl methacrylate) by an anionic grafting reaction. Unreacted polystyrene was separated by fractional precipitation. The composition of copolymer, i.e., the molecular weight of main chains and side chains, was determined. The influence of molecular weight and structure of graft copolymers on the intrinsic viscosity of solutions was examined. This may be expressed in the form [η] = KMagn. The dependence between a and n in this equation was established.
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  • 41
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 853-874 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In earlier work we have indicated a superposition principle for moderately concentrated mixtures (c ≲ 2/[η]) in good and poor solvents. By an examination of data on a number of vinyl polymers and cellulose derivatives in good as well as poor solvents, the validity of this principle is extended to concentrated solutions (c ≲ 50%). The characteristic concentration factor γ is proportional to M-a1 over the whole concentration range, with 0.47 ≤ a1 ≤ 1.10 being larger for good than for poor solvents, the result obtained earlier. Significant deviations from this relationship are noted in good solvents for those low molecular weights at which deviations from the usual intrinsic viscosity relationship occur. This may be related to the expansion factor of the polymer coil. On the basis of these results, the concentration and molecular weight dependence of the viscosity in the concentrated solution can be related to each other in terms of the parameter a1 and thus to thermodynamic characteristics. In this manner a bridge between the relatively dilute and concentrated regions is established. Currently used semiempirical expressions are analyzed in terms of these results. For the polystyrene-cyclohexane systems and θ - 9 ≦ T ≦ θ + 3, γ can be identified with the critical concentration for phase separation. Provided an “entanglement” concentration ce exists, in the neighbourhood of which the concentration dependence of the viscosity changes reapidly, γ can alternatively be shown to be proportional to ce, or ce ∝ M-a1. The temperature reduction scheme suggested earlier remains to be investigated.
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  • 42
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    Notes: Molecular weight M and concentration c dependencies of the zero-shear viscosity (η) were measured over wide ranges of M and c for concentrated solutions of linear and branched poly(vinyl acetate) as well as of polystyrene under θ conditions. The log η versus log M and log η versus log c curves for a given system can be superposed by the horizontal shift along the abscissa, giving smooth master curves. From the shift factors the ratio of two exponents β and α, which appear in the following equation, can be evaluated: η = K′(cρ)αMβ, where ρ is the density of the solution and K′ is a constant at constant temperature. The evaluated values of β/α for the systems under θ conditions are equal to or very close to 0.50 as was anticipated from the previous work. The above superposition method was also applied to available viscosity data, and it was found that β/α had a good correlation with a in [η] = KMa. This indicates that the individual molecules in concentrated solutions maintain the same individuality as in dilute solutions, and might be a positive support to the packed sphere model proposed previously by the authors. The effect of solvent on the molecular weight and the concentration dependencies of viscosity was also discussed.
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  • 43
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 915-927 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The homopolymer and many of the copolymers of N-acrylylglycinamide yield thermally reversible gels in water. These systems are uniquely suitable for studying synthetic photographic gelatin substitutes and for understanding the mechanism of the gelation process. Polymerization of N-acrylylglycinamide has been studied under a variety of conditions. The homopolymer is aggregated in dilute aqueous solution and probably molecularly dispersed in 2M thiocyanate solution. At concentrations of several per cent, in water, thermally reversible gels are formed whose melting points rise with increasing concentration and increasing molecular weight. The heat of gelation crosslinking has been calculated to be -8.8 kcal./mole of crosslinks. Introduction of small amounts of carboxyl groups into the polymer raises the melting points of the aqueous gels. The effect of various organic and inorganic reagents on gelation is presented. The ability to prepare copolymers which can be flocculated has been demonstrated as well as the usefulness of the monomer in certain types of photoresist systems. Copolymerization with acrylic acid and β-aminoethyl vinyl ether has been studied, and the r1 and r2 values for these systems have been calculated as well as Q and e values for N-acrylylglycinamide.
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  • 44
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1013-1028 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of the species of counterion on the polyelectrolyte behavior and the conformation of poly-L-methionine S-methylsulfonium salts in aqueous solution was studied by viscometric, electrochemical, and optical measurements. The degree of binding of small counterions to charged polyions increases in the sequence: chloride ≲ bromide 〈 iodide 〈 thiocyanate. The conformations of chloride and bromide salts are independent of polymer concentration. On the contrary, iodide and thiocyanate salts indicate a conformational transition, probably from a random-coil conformation to an intermolecularly stabilized β-form, with the increase of polymer concentration. The results suggest the existence of a strong specific interaction between counterion and macroion in iodide and thiocyanate salt solutions at high polymer concentration.
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  • 45
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 991-1012 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single-crystal preparations of polyethylene were treated with the selective oxidizing agent, fuming nitric acid. The degraded products were examined as regards layer thickness (by low-angle x-ray studies), chemical and weight changes, recrystallization and annealing treatments, and by broadline NMR, as part of a systematic investigation aimed at clarifying the nature of disordered material in single crystals. It emerges that there is a disordered-mobile region along the fold surface of the crystals in agreement with other parallel works along similar lines. In a more detailed analysis we can now decompose the nitric acid attack into components affecting the basal and side surfaces, respectively. Taking into account the recrystallization-annealing observations, we infer that the fold surface is heterogeneous with folds of more than one kind. These results were combined with a preliminary molecular weight distribution study by gel permeation chromatography. Taking into account all the available evidence, we are led to suggest a composite structure where surface looseness, coresponding to long loops and hairs, is superimposed on the more regular folded surface. This model is in the process of being tested. The problems concerning the assignment of a value to the amount of surface looseness are being discussed. In addition, a discontinuity in the thermal behavior of the crystals between 75 and 80°C. has been detected.
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  • 46
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1029-1042 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper is devoted to the determination of the number of intermolecular bonds in a polymer crosslinked according to the following process: (1) crosslinking in the usual isotropic state, (2) additional crosslinking of the strained primary network. The Flory equation for swelling in solvents has been modified in order to take into account the oriented state of the initial network at the time of secondary crosslinking. The combination of this equation with those relating the modulus of elasticity and the dimensions of the relaxed sample to the deformation of the primary network at the time of secondary crosslinking leads to different possible evaluations of the number of intermolecular bonds. Their significance is discussed. The equations thus established are tested with natural rubber samples vulcanized according to the above-mentioned process. The validity of the number of crosslinks thus calculated is discussed; a partial degradation of the primary network occurs during the second crosslinking. Its influence is taken into account by using the approximated equations proposed by Flory. The efficiency of the vulcanizing agent (TMTD) is consequently shown to be practically independent of the deformation of the primary network at the time of secondary crosslinking.
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  • 47
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1043-1053 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low-angle light-scattering patterns were obtained on ionotropic gels formed by the diffusion of Ca++ into a polygalacturonate sol. Near the sol-gel boundary, diffraction patterns were obtained which indicated organized structures with repeating units of 1100, 250, and 12.5 μ. Microscopic investigations confirmed that at this gel boundary capillaries run parallel to each other and perpendicular to the direction of diffusion. The diameter of capillaries was 12 μ while their length was in the 1000 μ range. Short interconnecting capillaries were about 200-300 μ in length. Inside the gel, in the more highly crosslinked parts, a disorientation occurs during the aging process with the partial disappearance of capillaries. However, at the gel-sol and gel-semipermeable membrane boundaries, the highly organized structures remain even during prolonged aging. The kinetics of the gel formation was also investigated.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1061-1066 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Osmotic pressures of aqueous solutions of poly(diethylaminoethyl methacrylate) hydrochloride, in equilibrium with a precipitate of the un-ionized polybase, at various concentrations of polymer and NaCl in solution and at different values of pH are derived from emf measurements and the “cell” theory for polyelectrolytes. Single-ion activities are evaluated according to two procedures. The first is based on measurements with ion-specific electrodes versus a calomel electrode. The second makes use of a salt bridge, but assumes that the co-ions have activity coefficients equal to the mean activity coefficient of the salt in a polyelectrolyte-free solution of the same concentration. The results show that the calculated values of the osmotic pressures are consistent with those obtained by the exact integration of the Gibbs-Duhem relationship, when the first procedure is employed. If, however, the single-ion activities are evaluated by the second procedure, the osmotic pressures obtained are consistently lower by about 10%. These differences arise because the two methods yield different values of the activity coefficients of the single ions.
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  • 49
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1079-1086 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic strain-optical coefficient of low-density polyethylene is found to decrease with increasing frequency and increase with increasing temperature (at temperatures up to 60°C.). It is found that a series of curves representing the real, K′, and imaginary, K″, parts of the frequency variation of the strain-optical coefficient obtained at various temperatures up to 60°C. may be superposed by translation along the frequency axis. The temperature dependence of the shift factor corresponds to an Arrhenius type equation with an activation energy of the order of 25 kcal./mole. This may be compared with the similar value obtained by Takayanagi for the αc′ mechanical loss and with the dynamic x-ray diffraction values reported by Kawaguchi et al., but is somewhat lower than the value of 34 kcal./mole reported by Onogi et al. from birefringence relaxation studies. Takayanagi has ascribed the αc′ peak to cooperative motion of crystalline and amorphous regions of the sort that might be involved in the suggested sliding of lamellae over each other. At temperatures higher than 80°C., horizontal superposition is not possible.
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  • 50
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The time-dependent birefringence has been measured simultaneously with the stress relaxation on quenched and annealed low-density polyethylene at various temperatures from 10 to 70°C. The strain-optical coefficient increases generally with increasing time, and approaches the equilibrium value, which depends upon the temperature. When the strain-optical coefficient at a fixed time is plotted against temperature, it first increases and then decreases after passing through a maximum at Tmax with increasing temperature. The higher the degree of crystallinity, the higher are the equilibrium values of the strain-optical coefficient and Tmax. The curves for strain-optical coefficient versus time and relaxation modulus versus time below Tmax can be superposed well by a horizontal shift along the abscissa. The optical shift factor obeys the original WLF equation, while the mechanical shift factor is much larger than the optical one. The molecular mechanisms corresponding to this dispersion of the strain-optical coefficient and viscoelastic αc absorption peak near Tmax are discussed.
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  • 51
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1145-1156 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory of rate processes has been applied by Eyring to the plastic flow of solids, but he considers only the case of simple shear. Some assumptions concerning a generalization of this theory for an arbitrary strain tensor are here proposed and discussed. The components of the deformation and the work done by the deviator of the stress during the elementary flow process are evaluated. According to these results, it can be proved that the yield condition of Huber, Hencky, and von Mises is valid when there is no hydrostatic stress. The discrepancy between the yield stresses corresponding to tensile and compressive tests is explained by the influence of the hydrostatic component and evaluated by taking account of the amount of free volume required for an elementary jump. The calculated value agrees with the experimental data. Measurements of the inclination of Lüder's bands and deformation components on poly(vinyl chloride) flat bars strained by tensile tests are in good agreement with the proposed theory.
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  • 52
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1157-1175 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Equations are developed for predicting the distributions of degree of substitution and block length in substitution copolymers which result when homopolymers are subjected to substitution reactions. Several different cases are treated differing in complexity from entirely random substitution to substitution affected by substituents already present on the same and on the neighboring repeat units. The equations are then applied to chlorinated polyethylene as an example of their use.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1177-1187 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of carbon black reinforcement was studied by examining stress-strain properties of preswollen (i.e., cured in the swollen state then deswollen) SBR-1500 vulcanizates and the effect of heat treatment on such samples. It was found that the supercoiling of molecular chains leads to a purely viscous response at low elongations. On heating of preswollen samples, molecular rearrangement at the carbon black surface occurs, leading to a considerable increase in modulus. The activation energy of that process was determined by using the superposition principle.
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The standard methods of measuring the elastic properties of polymer melts are briefly reviewed and a method of measuring another combination of viscoelastic properties, the melt strength, is described. Data are presented on the melt strength of various types of polyethylene resins and on ionomer resins. The effects on various viscoelastic properties of branching or of the addition of fine fibrils of Teflon perfluorocarbon resin are reported.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1293-1295 
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    Keywords: Physics ; Polymer and Materials Science
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  • 56
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1283-1292 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of microstructure on crystallizability of polyoctenamers prepared by R3Al-WCl6 catalyst was studied. The results indicate that polyoctenamers with a broad range of trans-vinylene content do crystallize. The measured melting points are dependent on the trans-vinylene content. From the dependence of melting temperature on copolymer composition, a value of 73 ± 2°C. for the melting point and a molar heat of fusion ΔHu of 3520 cal./mole are calculated for 100% trans-polyoctenamer. From the melting point depression in the presence of diluent, a value for ΔHu of 4800 cal./mole is obtained.
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  • 57
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    Notes: Current theories of polymer flow processes often sacrifice realistic molecular models for simplicity of their mathematical equations. An analysis of what might happen to molecules of more realistic sizes and shapes under shear flow, shows the importance of the rapid Brownian motion of chain segments, the elastic deformations of polymer random coils, and the dissipation of this elastic random coil energy by the relatively slow slippage of the chains past each other at a few entanglements where steric hindrance causes long relaxation times. This makes the energy loss depend on the time at each local deformation, and not on the overall shear rate. At high shear rates this model leads to “cluster flow” and low loss cyclic deformations, rather than the high loss processes of steady-state shear. This model gives reasonable qualitative explanations for many anomalous flow properties, and it has predicted new effects that have since been observed.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1317-1319 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
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  • 59
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    Notes: The crystallization kinetics and morphology of poly(tetramethyl-p-silphenylene)siloxane spherulites have been investigated over a temperature range of 25-130°C. The effect of molecular weight on the spherulitic growth rates, ranging from the monomer to molecular weights about 106, is discussed in terms of conventional rate theory. Surface free energies of crystal growth are computed on the basis of a spherulitic model in which the polymer chains are presumed to be incorporated within the lamellar crystallites which are comprised in the spherulites. Mention is made of the change in mechanical properties with molecular weight.
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  • 60
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 113-123 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The depolarized light intensity (DLI) technique detec's transitions in birefringent materials by simultaneously measuring sample temperature and intensity of polarized light roatated by the sample. Most polyolefins in the solid state rotate 30-40% of the polarized light. At any temperature at which the sample exhibits an ordered state, some rotation occurs. Temperatures of transitions and changes in refractive index can be determined in this way. Many of these transitions can also be followed by the well-known method of differential thermal analysis (DTA). A comparison of DLI and DTA curves of polyethylene, polypropylene, mixtures of these polymers, and block copolymers of ethylene and propylene shows the two techniques to be complementary and of use in determining the physical behavior of these polymers. Instrumentation and system variables of the DLI technique are discussed.
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  • 61
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 101-112 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The weight-average molecular weights of polymers of acrylonitrile prepared by a free-radical initiator and an organometallic catalyst have been determined by lightscattering measurements in N,N-dimethylformamide, dimethyl sulfoxide, and dimethylacetamide at 25°C. and in dimethyl sulfoxide at 140°C. The apparent molecular weights of the polymers prepared with the NaAlEt3S(i-Pr) catalyst in DMF at -78°C. (referred to as high-melting polymers) changed from 54,800, 82,700, and 480,000 when measured in DMF at 25°C. to 36,000, 41,600, and 225,000 when measured in DMSO at 140°C., whereas the molecular weights of the free-radical polymers remained unchanged. Furthermore, from results obtained in DMSO at 140°C., The intrinsic viscosity-molecular-weight relationships were found to be identical for the high-melting and the free-radical polymer and in substantial agreement with an equation reported by Cleland and Stockmayer. The apparent decrease in molecular weight of the high-melting polymer from 25 to 140°C. indicates rather clearly that the high-melting polymers are associated in DMF at 25°C. The “aggregates,” even though present only at low concentrations, raised the weight-average molecular weight markedly but affected the number-average molecular weight only slightly, thus giving a high M̄w/M̄n ratio. It appears likely that when temperature and solvent are such that association does not occur, linear PAN's will have approximately the same intrinsic viscosity-molecular weight relationship (subject of course to slight change by polydispersity). The often reported abnormal molecular weight of samples prepared by solution polymerization especially at low temperatures, may be attributed to branching, or to an association, as reported here. The nature of association of PAN in dilute solution is also discussed.
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  • 62
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 143-156 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The small-strain mechanical behavior of crystalline polyethylene has been studied by using a microstrain technique with strain resolution on the order of 10-6. The strain rate was varied from 10-6 to 10-4 sec.-1, and a temperature range of 17-28°C. was investigated. A strong dependence on strain rate and temperature has been observed for the following parameters which characterize the mechanical response of polyethylene in the microstrain region: the initial modulus of the stress-strain curve, the deviation in strain from ideal linear elastic behavior at a given stress amplitude, and the energy dissipated in a deformation cycle. The Young's moduli that were observed by means of tensile tests in the microstrain region were only about 20% lower than the values reported in other investigations at kilocycle and megacycle frequencies. The experimental method made it possible to isolate a deformation process which was attributed to a crystallographic shear mechanism corresponding to a yield point of 27 psi. This shear mechanism is discussed in terms of the various shear processes, such as slip, twinning, and the orthorhombic-monoclinic phase change.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 157-164 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rates of growth of single ozone cracks have been measured for vulcanizates of two butyl rubbers over the temperature range of 20-160°C. Over most of this range the rates are quantitatively related to the segmental mobility of the polymer and depend upon temperature in accord with the appropriate from of the WLF relation. The rates are also proportional to the concentration of ozone. It is therefore concluded that diffusion of ozone into the polymer before reaction is the rate-controlling step. This is contrasted with the behavior of butadiene-styrene copolymers, for which the rates of crack growth are also quantitatively related to the segmental mobility, but the rates are somewhat larger at equivalent mobilities and the dependence upon ozone concentration is smaller. The difference is attributed to different penetration distances before reaction in polymers containing low and high densities of reactive sites.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 235-236 
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    Keywords: Physics ; Polymer and Materials Science
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  • 65
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 263-270 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The adsorption of iodine by rayon tire yarn samples from aqueous solutions in which the concentration of iodide and triiodide ions is suppressed was studied. Fowler and Guggenheim's model of adsorption on regular localized monolayers appeared to be applicable to the adsorption phenomena considered. It is concluded that adsorption takes place on patches of sites in the cellulose-water gel.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 271-276 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: NMR linewidth studies of molecular motion in several polyacrylonitrile samples have been carried out. The motional transition temperature is found in the 105-124°C. range and depends upon polymerization conditions. In addition, the thermal activation energy for the motional process underlying this transition was evaluated at 16.4 kcal./mole. Finally, measurement of the transition temperature for one of the specimens in three different physical states (bulk, spun only, and spun and drawn with a ratio of 3:1), revealed that no change in the transition temperature was effected by either spinning or drawing.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 361-375 
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The polysaccharide of salep orchid tuber was shown to be a glucomannan with a glucose/mannose ratio of 2.6 and an acetyl content of 2.1%. After extraction from the powdered root with water, the triacetate derivative was prepared and its configurational and hydrodynamic properties examined. The polymer yielded a series of fractions from 615 to 4170 in weight-average degree of polymerization. Light-scattering, viscosity, and osmometry experiments were conducted. Intrinsic viscosity results were interpreted according to the hydrodynamic theory of Eizner and Ptitsyn resulting in a value of ζ/η0 = 20 ± 6 A. for the ratio of monomeric friction coefficient to solvent viscosity and a corresponding value of a = 55 ± 4 A. for the persistence length, closely similar to those reported for other β-1,4-linked polysaccharides. The theoretical Flory coefficient increased with increasing molecular weight but was less than the limiting value of Φ0 = 2.86 × 1023 mole-1. The dependence of the light-scattering radius of gyration of the glucomannan polymer on the contour length showed that the configuration of the heteropolymer was similar to that of other β-1,4-linked polysaccharides which have only glucose or mannose in the main chain. Calculated radii of gyration based on the Porod-Kratky persistence length were found to be smaller than radii found by light scattering on the fractions.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 394-396 
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    Keywords: Physics ; Polymer and Materials Science
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 377-390 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The concentrations and the growth rates of high- and low-melting type spherulites of trans-1,4-polyisoprene were measured in the temperature range 39-49°C. It was shown that above about 40°C., the crystallization rate of trans-1,4-polyisoprene is determined primarily by the radial growth rate of high-melting form (HMF) spherulites, whereas the predominance of the low-melting form (LMF) crystals below 40°C. can be attributed to the high rate of formation of LMF primary nuclei at lower crystallization temperatures. Temperature-independent rate parameters were calculated from optical and dilatometric measurements and were found to be in good agreement. Both the change in nucleation habit and spherulite growth rate with temperature can be explained on the basis of a lower end surface free energy of LMF crystals of trans-1,4-polyisoprene compared to that of the HMF crystals.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 397-397 
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 417-424 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The length of the span of the terephthaloyl residue in poly(ethylene terephthalate) guarantees independence of the conformations of successive repeating units of the chain. Interactions within units of the chain are amenable to interpretation by comparisons with related polymers; cis and trans conformations of the terephthaloyl residue are given equal weighting. The mean-square dimension ratio (〈r2〉0/M)∞ estimated on this basis is in substantial accord with the value deduced from experiments.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 425-429 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The error analysis for the transient vibrating reed test is developed based on a linearized approximation. Tables are given for the efficient utilization of the equations in evaluating the accuracy range of test data.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 431-454 
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The relationships between molecular weight distribution and structure in polymerizations with long-chain branching were reviewed and extended. Results were applied to an experimental examination of intrinsic viscosity in polydisperse, trifunctionally branched systems. Several samples of poly(vinyl acetate) were prepared by bulk polymerization under conditions of very low radical concentration. The relative rate constants for monomer transfer, polymer transfer, and terminal double-bond polymerization were established from the variation of Mn and Mw with the extent of conversion. Average branching densities were then calculated for each sample and ranged as high as 1.5 branch points/molecule. Intrinsic viscosities [η]B were measured in three systems: a theta-solvent, a good solvent, and one that was intermediate in solvent interaction. These results were compared with calculated viscosities, [η]L, which would have been observed if all the molecules had been linear. The values of [η]B/[η]L were substantially the same in all three solvents. The variation of this ratio with branching density was compared with the theory of Zimm and Kilb as adapted to polydisperse systems. Discrepancies were noted, and the adequacy of present model distribution functions for branched polymers was questioned.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 455-460 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of the size and shape of the torsional potential upon the theoretical temperature coefficient (T∂ ln 〈r02〉/∂T) of a polymeric chain was studied. The uncorrelated end-to-end distance equations for isotactic, syndiotactic, and completely atactic chains were differentiated with respect to temperature and the integrals in the resulting equations were evaluated by the method of Gaussian quadrature. The calculated coefficients were found to be nonlinear functions of the energy ratio Umax/KT, where Umax is the maximum potential barrier and possess real roots which critically depend upon the size and shape of the potential. Qualitative anomalies between experiment and theory disappeared when the entire torsional potential was used in the conformational theory. It appears that quantitative agreement between theory and experiment can be established for polymeric materials if the entire potential is used, rotations within bulky side groups are included, and the potential is determined by the method of minimum conformational energy.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 471-478 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Aqueous solutions of phosphotungstic acid were used to stain melt-crystallized polypropylene which had been oxidized to the leveled-off stage by boiling in 70% HNO3. Electron microscopy of thin sections of the polymer revealed unstained crystalline lamellae bordered by stained interlamellar layers. The lamella height, which is equivalent to the fold period of the molecules, increased as the crystallization temperature increased. In polypropylene which had crystallized in ice water, and at 125, 145, or 161°C., the heights of the visually delineated lamellae were 80, 105, 158, and 210 A., respectively. Those heights were, in turn, approximately the same as the length of the perpendicularly aligned molecules in the lamellae, which survived the acid etch. The stained interlamellar layers, regardless of the crystallization temperature, were about half the height of the lamellae.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 663-670 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Current network theory exhibits inconsistencies which show up particularly clearly in deformation of networks prepared by crosslinking a polymer in solution. A check of theory can be obtained if one knows precisely the number of crosslinks in the network and if a range of deformations is applied to the network. In an effort to explore this problem we have examined the relation of shear modulus to crosslink density, primary molecular weight, and polymer concentration for a series of poly(vinyl alcohol) gels at low to intermediate concentrations. Aqueous poly(vinyl alcohol) solutions were crosslinked to form infinite networks using terephthalaldehyde. We find a large discrepancy with these poly(vinyl alcohol) gels between measured shear modulus and that calculated from classical elasticity theory assuming quantitative reaction of crosslinking. The ratio of measured to calculated modulus is independent of crosslink density for a given primary molecular weight and concentration. It shows linear dependence on polymer concentration prior to crosslinking and extrapolates to a critical concentration which is consistent with the effective sizes of the polymer molecules.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 671-684 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rate of water sorption at 25°C. has been determined for a number of polyacetal films differing in structure, density, and orientation induced by extrusion. The equilibrium water uptake was found to be a linear function of density only; no other effect of structure or orientation was detectable. The extrapolated density for zero sorption was 1.51 g./cc., not far from the theoretical crystalline density. The diffusivity of water in unoriented films rose with decreasing density; for linear copolymer, the trend was parallel to that of the area under the dynamic mechanical loss peak associated with long-range chain motions in the disordered regions (β-transition). Less pronounced effects of molecular weight and long chain branching on diffusivity were also noted. Films crystallized while an extruded melt was still oriented showed considerable increases in water diffusivity, but no significant changes in the apparent activation energies of permeation (about 6.6 kcal./mole) or diffusion (about 11.5 kcal./mole). On annealing these films, the diffusivity remained almost constant while the sorption coefficient and retraction on remelting decreased.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 685-696 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cavity model used in the theory of dielectrics was applied to hydrodynamics to calculate the force exerted by a system of soft dumbbells on a reference dumbbell in a hydrodynamic field. The influence of this force on the viscosity and flow birefringence and its dependence on both the concentration and velocity gradient were calculated. The system of equations has a real solution only for values of β = M[η]η0γ/RT which are smaller than a critical value rapidly decreasing with increasing concentration. At zero concentration the results obtained agree with the theory of a single isolated dumbbell model. The calculated Huggins constant is k′ = 0.4. The extinction angle is connected with the relative viscosity very nearly as derived from experiments. However, the theory fails at higher concentrations and gradients yielding an increase in viscosity with the gradient and infinite zero-shear viscosity for the concentration c = 2.5/[η].
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 697-704 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of the spin-lattice relaxation times (T1) of solvent protons have been performed on systems containing mixed solvents with and without polymer. It has been found that the motion of solvent is selectively affected by polymers present in the system. Polyisobutylene (10%) in mixed solvents of carbon tetrachloride (or cyclohexane) and dichloromethane at various proportions produces little effect on T1 values of dichloromethane, but it affects significantly the T1 values of cyclohexane; whereas poly(methyl methacrylate) (10%) in carbon tetrachloride and dichloromethane (or acetone) selectively associates with dichloromethane (or acetone), resulting in an approximate 50% reduction of the T1 values for dichloromethane (or acetone). In systems of poly(methyl methacrylate) and three mixed solvents of carbon tetrachloride, dichloromethane, and cyclohexane, the polymer (10%) has a negligible effect on the T1 values of cyclohexane, but brings about a 50% reduction of the T1 values of dichloromethane. These phenomena are discussed in terms of local selective interactions between the solvent molecules and the polymeric chain segments.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 711-742 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A general method is presented for taking into account changes in volume in several types of calculations concerned with spherulite deformation in semicrystalline polymers. The method is applicable at large strains for which the low-strain limiting form of the equation defining Poisson's ratio is no longer valid. Applications are made to calculations of the three crystal orientation functions for models of spherulite deformation based on those proposed by Wilchinsky, Stein et al., and Oda et al. The effects of changes in volume are considered in detail and are compared with previous results in which the volume change was neglected. Calculations of spherulite birefringence are considered in a similar manner, as are the equations for determining spherulite deformation by means of low-angle light-scattering measurements. Results indicate that in several cases details of deformation mechanisms previously proposed should be revised in light of the effect of the change in volume on the calculated orientation functions. The equations in each case are presented in terms of a parameter β, the square root of the third strain invariant of the deformation tensor. Results are presented in numerical form for many of the basic parameters. Equations for all such results are expressed in explicit form and, in most cases, are displayed graphically together with available experimental data.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1055-1059 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method of evaluating osmotic coefficients of polyelectrolyte solutions is suggested for systems in which a two-phase equilibrium is maintained between the polymer solution and a polymer precipitate so that the “polymer” terms Cpdμp in the Gibbs-Duhem relationship may be neglected. The method is applied to a polybase system, and the osmotic coefficients calculated from the experimental data are discussed in terms of the theory of Alexandrowicz. The results are found to be in line with the above theory but the characteristic parameter φp, the fraction of free counterions, is about twice as large as values previously observed in polyacids.
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1087-1101 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of long-chain branching on the size of low-density polyethylene molecules in solution is demonstrated through solution viscosity and molecular weight measurements on fractionated samples. These well-characterized fractions are analyzed by gel permeation chromatography (GPC), and it is shown that the separation of the polymer molecules by this technique is sensitive to the presence of long-chain branching. By using fractions of branched polyethylene possessing differing degrees of branching, one observes that a single curve is adequate in relating elution volume to molecular weight. This calibration curve is applied in the GPC analysis of a variety of commercial low-density polyethylene resins and it is shown, by comparison with independent osmometric and gradient elution chromatographic data, that realistic values for molecular weight and molecular weight distribution are obtained. The replacement of molecular weight M by the parameter [η]M as a function of elution volume, leads to a single relationship for both linear and branched polyethylenes. This indicates that GPC separation takes place according to the hydrodynamic volumes of the polymer molecules. The comparison of data for polyethylene and polystyrene fractions suggests that this volume dependence of the separation will be observed for other polymer-solvent systems.
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  • 83
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1103-1118 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Data on wettability of elastomers should be considered basic to the understanding of all phases of elastomer adhesion. However, no such data in the form of critical surface tensions were available for elastomers other than polydimethylsiloxane. For this study, 18 elastomers were selected to determine the effects of functional groups, of geometrical and structural isomerisms, of copolymerization, and of the induced orientation upon wettability. Most results support the constitutive law of wettability established by Shafrin and Zisman. The effect of structural isomerisms in the form of a vinyl side group and cyclization is discussed. An equation for the calculation of critical surface tension of a copolymer or of a mixture of isomers is proposed as follows: \documentclass{article}\pagestyle{empty}\begin{document}$ \gamma _c {\rm (copolymer or mixture of isomers)} \simeq \sum\limits_1^\infty {N_i \gamma _{c_i } } $\end{document} where Ni is the mole-fraction of the individual monomer in the copolymer and \documentclass{article}\pagestyle{empty}\begin{document}$ \gamma _{c_i } $\end{document} is the critical surface tension of each homopolymer. Most elastomer adhesion studies conducted in the past were concerned with the diffusion theory of adhesion. This study further supports the conclusion on the role of diffusion and adsorption in adhesion advanced in Part I, especially with respect to the physical state of polymer at the time of application. The wettability data in this study could shed some light upon major basic mechanisms involved in elastomer reinforcement.
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  • 84
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1119-1144 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experimental data obtained from stress-strain curves of five different textile fibers, at a series of different, constant strain rates covering a range of 61/2 decades have been used to study two methods of nonlinear viscoelastic analysis proposed elsewhere. According to the first of these, time and strain effects are factorizable so that stress σ, strain ε and time t are related by the equation σf1(ε)/ε = f(t),. This is shown to be unsatisfactory with the present materials, but an empirical modification to σf1(ε)/ε = f2(ε) + f(t) is satisfactory. According to the second, general nonlinear viscoelastic behavior can be described by an equation which reduces to the form σ/ε = F1(t) + εF2(t) + ε2F3(t) + when applied to extension at a constant strain rate. This series is shown to be strongly divergent except at fairly small stains. In fact, if it is truncated after about three terms, which are as many as can be estimated with any significance in the present experiments, it is applicable only to strains of about 3-4% and less. Numerical techniques which enable standard statistical procedures to be used have been devised to perform the above analyses and are described in detail.
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  • 85
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory of the equilibrium distribution of a mixture of different size species of a polymer between two liquid phases is reviewed and used as a basis for the calculation of the dependence of fractionation efficiency on overall concentration, interaction coefficient (hence, choice of solvent and temperature), average molecular weight, and the spread of the molecular weight distribution in the polymer. The special case of a single type of polymer in a single solvent, for which the polymer-solvent interaction coefficient is independent of concentration, is dealt with quantitatively. The ultimate aim is to make it possible to determine systematically the optimum solvent (or mixture of solvents), temperature, and overall concentration for fractionation of a given type of polymer, having a given average molecular weight and molecular weight distribution, considering practical limitations, e. g., the total volume which can conveniently be handled and the time required to achieve a sufficiently close approach to equilibrium.
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  • 86
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1296-1299 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 87
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    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 1300-1304 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 88
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    Zeitschrift für anorganische Chemie 354 (1967), S. 37-43 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The existence of 2 ZnO · 3 B2O3 · 7 and 7,5 H2O as crystalline phases in the system ZnO—B2O3—H2O at 20°C is confirmed. Both hydrates, although reproducibly formed at different conditions, have the same X-ray powder pattern and IR spectrum. Hydrothermally (165°C/16 hrs.) were prepared: 2 ZnO · 3 B2O3 · 3 H2O, ZnO · 5 B2O3 · 4.5 H2O and 6 ZnO · 5 B2O3 · 3 H2O, the latter having the same powder pattern as 4 ZnO · 3 B2O3, but a different IR spectrum.
    Notes: Als kristalline Phasen im System ZnO—B2O3—H2O bei 20° werden bestätigt 2 ZnO · 3 B2O3 · 7 und 7,5 H2O. Beide Hydrate sind gezielt darstellbar, unterscheiden sich aber weder röntgenographisch noch IR-spektroskopisch. Unter hydrothermalen Bedingungen (165°, 16 h) wurden aus ZnO und H3BO3 mit und ohne Wasserzusatz gewonnen: 2 ZnO · 3 B2O3 · 3 H2O, ZnO · 5 B2O3 · 4,5 H2O und 6 ZnO · 5 B2O3 · 3 H2O. Letztere Verbindung ist röntgenographisch nicht, wohl aber IR-spektroskopisch von 4 ZnO · 3 B2O3 zu unterscheiden.
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  • 89
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    Zeitschrift für anorganische Chemie 354 (1967), S. 69-73 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The preparation and infrared spectra of triphenyl-tin and -lead tricyanomethanide, (C6H5)3MNCC(CN)2, and of diphenylthallium tricyanomethanide, (C6H5)2TlNCC(CN)2, are reported.
    Notes: Die Darstellung und IR-Spektren von Triphenylzinn- und -bleitricyanomethanid, (C6H5)3MNCC(CN)2 (M = Sn, Pb), sowie von Diphenylthalliumtricyanomethanid, (C6H5)2TlNCC(CN)2, werden beschrieben.
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  • 90
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    Zeitschrift für anorganische Chemie 354 (1967), S. 78-84 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 2,6-spinels Co5TeO8, CoZn4TeO8 and NiZn4TeO8 were prepared. They have a primitive cubic superstructure. The light absorption of these phases was investigated. Only small shifts of the absorption bands compared with those of the 2,5-spinels of Sb5+ were observed.
    Notes: Die 2,6-Spinelle Co5TeO8, CoZn4TeO8, NiZn4TeO8 wurden dargestellt. Sie haben eine primitiv-kubische Überstruktur. Die Lichtabsorption dieser Phasen wurde untersucht. Die Lagen der Banden sind im Vergleich mit denen entsprechender 2,5-Spinelle des Sb5+ nur geringfügig verschoben.
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  • 91
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    Zeitschrift für anorganische Chemie 354 (1967), S. 90-97 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mit Hilfe der IR-Spektrometrie sind die Komplexe von Benzhydrazid und Salicylhydrazid mit einigen zweiwertigen Metallionen der ersten Übergangsreihe untersucht worden. Die Ergebnisse zeigten, daß die Liganden in der Ketoform gebunden sind und daß die phenolische OH-Gruppe des Salicylhydrazids bei der Chelatbildung nicht beteiligt ist. Die Ketoform wurde auch mit Ionen-Wanderungsversuchen und Leitfähigkeitstitrationen bestätigt. Die Zusammensetzung der in Lösung gebildeten Komplexe wird ebenfalls diskutiert.
    Notes: Complexes of benzhydrazide and salicylhydrazide with some divalent metal ions of the first transition series are investigated by IR-spectrophotometry. The study showed that the organic ligand exhibited the ketonic form and that the phenolic OH-group of salicylhydrazide is not participating in chelate formation. The ketonic structure of the benzhydrazide ligand is also attained in solution as supported by the results of migration experiments and conductometric titrations. The stoichiometry of the complexes formed in solution is also studied.
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  • 92
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    Zeitschrift für anorganische Chemie 354 (1967) 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 93
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    Zeitschrift für anorganische Chemie 354 (1967), S. 130-138 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: β-Amino-ethylpyridine-(2) (AÄP) and β-methylamino-ethylpyridine-(2) (MAÄP) react with NiII to mixed-anionic complexes of the type NiL2(NO2)X (L = AÄP, MAÄP, X = ClO4, I, Br). The electronic and vibrational spectra give evidence for a bidentate chelate behaviour of the nitrite group in these complexes.Ni(AÄP)2(NO2)2 exists in two isomeric forms, one being blue and of the mixed-anionic complex type, the other being red and having a dinitro structure.
    Notes: β-Amino-äthylpyridin-(2) (AÄP) und β-Methylamino-äthylpyridin-(2) (MAÄP) bilden mit Nickel(II)-Ionen gemischt anionische Komplexe der Typen Ni(AÄP)2(NO2)X bzw. Ni(MAÄP)2(NO2)X (X = CIO4, J, Br). Wie aus den optischen und Schwingungsspektren hervorgeht, fungiert das Nitrit in diesen Verbindungen wahrscheinlich als zweizähliger Chelatligand.Ni(AÄP)2(NO2)2 existiert in Form zweier Isomeren, von denen das blaue strukturell den gemischt anionischen Komplexen an die Seite zu stellen ist, während das rote eine Dinitrostruktur besitzt.
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  • 94
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aluminium oxide samples, prepared from hydroxides and oxides at 400°-1000°C, have been characterized by estimating the specific surface, pore size distribution function, and primary particle size. Relations between secondary structure, degree of crystallinity, and dehydrating activity are communicated. The differing activities of oxides, which were obtained at 800°C from starting materials having various degrees of crystallinity, are explained by topotactic thermal transformations.
    Notes: Aus Aluminiumhydroxiden und -oxid wurden durch Glühen zwischen 400° und 1000°C Reihen von Tonerden hergestellt. Von den Tonerden wurden die spezifische Oberfläche, die Verteilung der Übergangsporen und die Primärteilchengrößen gemessen. Es werden die Beziehungen zwischen der Sekundärstruktur, dem kristallinen Anteil und der Dehydratisierungsaktivität besprochen. Die Aktivitätsunterschiede für die Oxide, die bei 800°C aus Ausgangssubstanzen mit stark unterschiedlichem Kristallisationsgrad hergestellt wurden, werden topotaktisch erklärt.
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  • 95
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    Zeitschrift für anorganische Chemie 354 (1967), S. 201-207 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: UO22+-Ionen bilden nach potentiometrischen und spektrophotometrischen Messungen mit N-Hydroxyäthyl-äthylendiamin-triessigsäure und Äthylenglykol-bis(aminoäthyl)-äther-tetraessigsäure 1:1-und 1:2-Komplexe, die zum Teil als basische UO2(OH)-Komplexe vorliegen. Es wurden die Bildungskonstanten ermittelt.
    Notes: Detailed investigations have been carried out of the reaction of uranyl ion with N-hydroxyethyl ethylene-diaminetriacetic acid and ethyleneglycol bis-(2-aminoethyl) ether tetraacetic acid by potentiometric and spectrophotometric methods. Evidence is presented for the formation of 1:1 and 2:1 complexes and the corresponding hydroxy species. The formation constants of all these species were determined by spectrophotometric method.
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  • 96
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    Zeitschrift für anorganische Chemie 354 (1967), S. 172-183 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Activity coefficients of nickel and cobalt sulfate have been determined from solubility measurements in the systems NiSO4 · H2O resp. CoSO4 · H2O — (NH4)2SO4 — H2O at 160-300°C by applying the DEBYE-Hückel theory. The logarithmic expression obtained (see “Inhaltsübersicht”) holds for pure solutions and those containing ammonium sulfate at ionic strengths 0 ≤ I ≤ 4 at temperatures ranging from 25 to 300°C.For temperatures between 160 and 300°C, equilibrium constants and standard enthalpies and entropies of solution, ΔH°(T) and ΔS°(T), are given for the equilibria investigated. The thermodynamic data for 25°C (see „Inhaltsübersicht“) have been calculated by extrapolation.The standard entropies of the monohydrates have been found to be S2980 (NiSO4 · H2O) = 33 and S2980 (CoSO4 · H2O) = 43 cal/mole·degree.
    Notes: Aus Löslichkeitsmessungen an den Systemen NiSO4 · H2O bzw. CoSO4 · H2O — (NH4)2 SO4 — H2O im Temperaturbereich von 160-300°C werden die Aktivitätskoeffizienten von Nickel- und Kobaltsulfat mit Hilfe der Debye-Hückelschen Theorie zu \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm lg}\;\gamma _{{\rm NiSO}_{\rm 4} } = {\rm lg}\;\gamma _{{\rm CoSO}_{\rm 4} } = - 4{\rm A}\frac{{\sqrt {\rm I} }}{{{\rm 1 + 1,25}\sqrt {\rm I} }} - 0,041 \cdot {\rm I} $$\end{document} bestimmt. Diese Beziehung ist für reine und Ammoniumsulfat enthaltende Lösungen bei Ionenstärken 0 ≤ I ≤ 4 im Temperaturbereich von 25-300°C gültig. Für 25°C liefert sie Aktivitätskoeffizienten, die mit Angaben der Literatur für Nickelsulfat gut übereinstimmen.Für die untersuchten Gleichgewichte MeSO4 · H2O = Me++ + SO4- + H2O (Me = Ni, Co) werden die Gleichgewichtskonstanten und die Standardlösungsenthalpien ΔH°(T) und -entropien ΔS°(T) zwischen 160 und 300°C angegeben. Durch Extrapolation auf 25°C werden folgende thermodynamische Werte berechnet: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm NiSO}_{\rm 4} \cdot {\rm H}_{\rm 2} {\rm O} = {\rm Ni}^{{\rm + + }} + {\rm SO}_{\rm 4}^{ - - } + {\rm H}_{\rm 2} {\rm O,}} \hfill \\ {\Delta {\rm H}_{{\rm 298}}^{\rm 0} = - 12{{{\rm kcal}} \mathord{\left/ {\vphantom {{{\rm kcal}} {{\rm Mol}}}} \right. \kern-\nulldelimiterspace} {{\rm Mol}}},\;\Delta {\rm S}_{{\rm 298}}^{\rm 0} = - 42{{{\rm cal}} \mathord{\left/ {\vphantom {{{\rm cal}} {{\rm grad\;Mol}}}} \right. \kern-\nulldelimiterspace} {{\rm grad\;Mol}}}.} \hfill \\ {{\rm CoSO}_{\rm 4} \cdot {\rm H}_{\rm 2} {\rm O} = {\rm Co}^{{\rm + + }} + {\rm SO}_{\rm 4}^{ - - } + {\rm H}_{\rm 2} {\rm O,}} \hfill \\ {\Delta {\rm H}_{{\rm 298}}^{\rm 0} = - 13{{{\rm kcal}} \mathord{\left/ {\vphantom {{{\rm kcal}} {{\rm Mol}}}} \right. \kern-\nulldelimiterspace} {{\rm Mol}}},\;\Delta {\rm S}_{{\rm 298}}^{\rm 0} = - 48{{{\rm cal}} \mathord{\left/ {\vphantom {{{\rm cal}} {{\rm gradMol}}}} \right. \kern-\nulldelimiterspace} {{\rm grad\;Mol}}}} \hfill \\\end{array} $$\end{document}.Die Normalentropien der Monohydrate ergeben sich zu \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm S}_{{\rm 298}}^{\rm 0} \left({{\rm NiSO}_{\rm 4} \cdot {\rm H}_{\rm 2} {\rm O}} \right) = 33{\rm \;und\;S}_{{\rm 298}}^{\rm 0} \left({{\rm CoSO}_{\rm 4} \cdot {\rm H}_{\rm 2} {\rm O}} \right) = 43\;{{{\rm cal}} \mathord{\left/ {\vphantom {{{\rm cal}} {{\rm gradMol}}}} \right. \kern-\nulldelimiterspace} {{\rm grad\;Mol}}} $$\end{document}.
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  • 97
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    Zeitschrift für anorganische Chemie 354 (1967) 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 98
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    Zeitschrift für anorganische Chemie 354 (1967), S. 273-286 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: In the La2O3 — U2O5 system (16 - 60 mol-% LaO1,5) the following phases are observed: In the 16 - 33 mol-% LaO1,5 region: U3O8 and a (La, U(V), U(IV)) fluorite phase; 33 - 47 mol-% LaO1.5:a (La, U(V)) fluorite phase; 50 - 60 mol-% LaO1.5:a fluorite and a rhombohedral phase.The fluorite-type compounds ScUO4, YUO4, NdUO4, SmUO4, EuUO4, GdUO4 and UbUO4 have been prepared.BiUO4 crystallizes in the fluorite structure (a = 5.481 Å). On the uranium rich region of the Bi2O3 — U2O5 system, a (Bi, U(V), U(IV)) fluorite phase and U3O8 are formed. With a Bi: U ratio 〉 1 a fluorite phase, bismuth and Bi2UO6 are found. BiUO4 is reduced by UO2, with UO2.25 a (Bi, U(V), U(IV)) fluorite phase is formed.FeUO4 is isomorphous with CrUO4. The reflectance spectra of the compounds are given.
    Notes: Im System La2O3 — U2O5 treten in Bereich zwischen 16-60 Mol-% LaO1,5 folgende Phasen auf: U3O8 neben einer (La, U(V), U(IV)-Fluoritphase (16 - 33 Mol-%, LaO1,5) eine (La, U(V))-Fluoritphase (33 - 47 Mol-% LaO1,5), eine Fluoritphase und eine rhomboedrische Phase (50 - 60 Mol-% LaO1,5).Es werden die folgenden im Fluorigitter kristallisierenden U(V)-Verbindungen dargestellt: ScUO4, YUO4, NdUO4, SmUO4, EuUO4, GdUO4 und YbUO4.BiUO4 (a = 5,481 Å) besitzt eine nur sehr geringe Phasenbreite. Auf der uranreichen Seite des Systems Bi2O3 — U2O5 existiert eine (Bi, U(V), U(IV))-Fluoritphase neben U3O8. Bei einem Bi: U-Verhältnis 〉 1 entstehen neben einer Fluoritphase Wismutmetall und Wismuturan(VI)-oxid. Durch UO2 wird BiUO4 reduziert, mit UO2,25 bildet es eine (Bi, U(V), U(IV))-Fluoritphase.FeUO4 kristallisiert wie CrUO4 rhombisch. Es werden die Reflexionsspektren der beiden Verbindungen mitgeteilt.
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  • 99
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    Zeitschrift für anorganische Chemie 354 (1967), S. 307-312 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Mössbauer spectra of H2SnCl6 · 6 H2O, K2SnCl6, (NH4)2SnCl6, MgSnCl6 · 6 H2O, CaSnCl6 · 6 H2O and NiSnCl6 · 6 H2O have been determined at 77°K. Isomeric shifts with respect to the resonance line of SnO2 have been found to range between (0.46 - 0.49) ± 0.06 mm/sec. The dependence of the width at half-maximum of the resonance lines upon the thickness of the absorber has been studied at 77°K. On the basis of the data obtained it is assumed that widening of the resonance lines is caused by quadrupole interaction.The temperature dependence of the resonance effect has been investigated on the above compounds. The character of this dependence supports the conception about a correlation between the weak temperature dependence of the probability (f′) for recoilfree γ-quanta absorption and the low melting point of some tin compounds.
    Notes: Die Mössbauer-Spektren von H2SnCl6 · 6 H2O, K2SnCl6, (NH4)2SnCl6, MgSnCl6 · 6 H2O, CaSnCl6 · 6 H2O und NiSnCl6 · 6 H2O wurden bei 77°K aufgenommen. Die Isomerieverschiebungen (gegenüber der SnO2-Linie) liegen im Intervall zwischen (0,46-0,49) ± 0,06 mm/Sek. Die Abhängigkeit der Halbmaximumbreite der Resonanzlinien von der Absorberdicke wurde bei einer Temperatur von 77°K untersucht. Die experimentellen Daten lassen vermuten, daß die Resonanzlinien unter dem Einfluß einer Quadrupolwechselwirkung verbreitert sind.Die Temperaturabhängigkeit der Größe des Resonanzeffektes wurde bei obigen Verbindungen verfolgt. Der Charakter dieser Abhängigkeit unterstützt die Auffassung von einem Zusammenhang zwischen der schwachen Temperaturabhängigkeit der Wahrscheinlichkeit (f′) einer rückstoßfreien Absorption von γ-Quanten und dem niedrigen Schmelzpunkt mancher Zinnverbindungen.
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  • 100
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    Zeitschrift für anorganische Chemie 355 (1967), S. 1-11 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: In the systems ZnO—Nb2O5 and ZnO—Ta2O5 the phases Zn3Nb2O8 (I) and Zn3Ta2O8 (II) exist. Substituting some Zn in (II) by Co, Ni or Cu the structure changes from (II) to that of (I).The light absorption of Co2+, Ni2+, Cu2+ in these phases is investigated. Therefrom it is deduced that the bivalent cations in (II) occupy octahedral and tetrahedral sites, but in (I) only octahedral ones.
    Notes: In den Systemen ZnO—Nb2O5 und ZnO—Ta2O5 existieren die Phasen Zn3Nb2O8 (I) und Zn3Ta2O8 (II). Ersetzt man in (II) größere Mengen Zn durch Co, Ni oder Cu, so geht die Struktur von (II) in die von (I) über.Die Lichtabsorption von Co2+, Ni2+ und Cu2+ in diesen Phasen wird untersucht. Daraus ergibt sich, daß die zweiwertigen Kationen in (II) Oktaeder- und Tetraederlücken besetzen, in (I) jedoch nur Oktaederlücken.
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