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  • Physics  (5,197)
  • Wiley-Blackwell  (5,197)
  • Cambridge University Press
  • 1980-1984  (2,657)
  • 1975-1979  (2,540)
  • 101
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1037-1040 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of particle size on glass transition temperatures is discussed. The phenomenon is treated in terms of Ehrenfest second-order thermodynamics and in addition related to free volume concepts. Consistent formulas are obtained and the order of magnitude of the effect is estimated.
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  • 102
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1067-1075 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The differential scanning calorimetry (DSC) melting curves of drawn nylon 6 were studied from the standpoint of reorganization of the crystals during the heating process. A new method was presented to obtain the DSC curve associated with the growth and melting of the original crystals, and that with the recrystallization and final melting process, separately. The results obtained show that, in the case of a heating rate of 10°C/min, the original crystals in the sample start perfecting themselves at temperatures far below their initial melting temperature and melt out below 222°C, recrystallization starts at about 210°C, and the newly emerged crystals melt out at 228°C. The superposition of two such constructed DSC curves reproduces the observed DSC curve well. Therefore, the double melting peaks of the sample are considered to be the result of superposition of three processes which occur successively during heating; perfection of the original crystals, melting of the perfected crystals concurrently with recrystallization, and melting of the recrystallized crystals.
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  • 103
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1129-1142 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of molecular weight heterogeneity on the second virial coefficient A2 in good solvents is studied for binary mixtures of monodisperse poly(α-methylstyrenes). It is concluded that A2 for polymer mixtures passes through a maximum with variation of the mixing ration. From comparison with the data, it is concluded that no available theory quantitatively explains both the molecular weight dependence of A2 of monodisperse polymer and the variation of A2 of mixtures with the mixing ratio. The interpenetration function for two polymer coils with different molecular weights is discussed on the assumption that the thermodynamic interaction between two polymer coils in good solvents can be approximated by a hard-sphere model.
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  • 104
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1651-1653 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 105
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1267-1281 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The anisotropy of thermal conduction in a spherulite is calculated for a two-phase model. The problem of the temperature distribution due to cooling of a spherulite suddenly heated at one point is solved. An analytical result is given and isothermal contours are calculated for wide ranges of thermal conduction anisotropy and cooling time. Experiments with spot-heated isotactic polypropylene (i-PP) and isotactic polystyrene (i-PS) spherulites were conducted using a laser pulse and a needle as heat sources. The isotherms were recorded using a thin coating of a heat-sensitive indicator substance, and then by comparison with theoretical isotherm patterns the heat conduction anisotropy of a PP spherulite was estimated. Additional measurements of heat conduction coefficients of at least two polymer films characterized by different crystallinity permit calculation of the thermal conductivity of the amorphous phase, and the conductivities of single crystals along chains and perpendicular to the chains. The results show that the heat is transferred mainly along the primary bonds of polymer chains. However, the morphology of sperulites and lamellas plays an important role.
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  • 106
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1315-1317 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 107
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1339-1345 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Raman depolarization (ρ) measurements have been made over the temperature range 20 〉 T 〉 60°C for solutions of poly(dimethyl siloxane) (mol wt 7.7 × 104 and 2.0 × 104) for several concentrations up to 100%. The band studied was the highly polarized methyl stretch at 2907 cm-1. Computer calculations of the probability pt of a rotational isomer being trans allow the ρ values to be related to ΔG, the free energy of mixing. ΔG is plotted as a function of concentration and minima are observed at 60 ± 3% (mol wt = 7.7 × 104) and 70 ± 3% (mol wt = 2 × 104).
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  • 108
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1397-1407 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric constants have been determined for a fraction of poly(diethylene terephthalate) in benzene at several temperatures. The data indicate that the dipole moment ratio 〈μ2〉/Nm2 is somewhat higher than that of poly(ethylene oxide), and its temperature coefficient is in the vicinity of zero. Both the dipole ratio and its temperature coefficient are in very good agreement with those predicted by the rotational isomeric state theory. Using this theory, the unperturbed dimensions of poly(diethylene terephthalate) were calculated and it was found that (〈r2〉/M)∞ = 0.80 Å2 (g mol wt)-1, a value intermediate between those of poly(ethylene oxide) (0.57) and poly(ethylene terephthalate) (1.05).
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  • 109
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1451-1473 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Monomer distributions and number-average sequence lengths are determined from 13C nuclear magnetic resonance (NMR) data for 1,4- and 1,2-butadiene additions and styrene additions in a series of four hydrogenated butadiene-styrene copolymers. The monomer distribution is expressed in terms of the six unique days from which it is possible to calculate the number-average sequence length of each monomer type. Carbon-13 NMR spectral assignments are given and the techniques for making the assignments are discussed. The method presented could, in principle, be applied to any copolymer or terpolymer. Limitations that are encountered in the analysis of hydrogenated butadiene-styrene copolymers high in 1,2 additions are discussed.
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  • 110
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1507-1520 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A differential scanning calorimeter (DSC) was used to study the melting behavior of drawn nylon 6 yarns which were prevented from shrinking during heating. The DSC curves exhibit a single melting peak at a higher temperature instead of the double peaks which, as reported previously, were observed in the unconstrained state. The curve is explained quantitatively in terms of the perfecting of the original crystals followed by monotonic melting of these crystals during heating. The single peak results from the absence of the partial melting-recrystallization process which plays an important role in the appearance of double peaks. The temperature of the melting peak for the constrained sample increases linearly with draw ratio, and is unaffected by drawing temperature and by annealing at constant length after drawing. The elevation of the melting temperature is discussed on the basis of the entropy effects predicted theoretically by Zachmann. Thermal analysis of constrained samples has proved to be useful for detecting oriented crystals which coexist with unoriented ones.
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  • 111
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1241-1255 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fibers were drawn from polymers of octadecyl acrylate, octadecyl methacrylate, N-octadecylacrylamide, and a series of N-substituted acrylamides with a second amide group in the side chain as well as from copolymers of octadecyl and methyl esters of acrylic and methacrylic acid. Wide-angle and small-angle x-ray diffraction patterns were recorded for these materials. The interpretation of the characteristic difference between the behavior of the polycrylates and polymethacrylates, as proposed by Platé and his collaborators, is found to be inconsistent with a number of features of the experimental evidence. In the case of poly(octadecyl methacrylate) the data allow the estimation of two parameters of the electron density distribution in the side-chain crystallites. With polyacrylamide derivatives, a second amide group in the side chain is found to destabilize the side chain crystallites. The bahavior of the copolymers is very complex and exhibits, in one case, evidence for a long periodicity parallel to the fiber axis.
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  • 112
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1287-1295 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Hydrophobic-hydrophilic block copolymers were prepared by “living” anionic polymerization. They consist of polystyrene and poly(ethylene oxide) blocks, and are soluble in water. Their interfacial properties were investigated, employing aqueous solutions. The block copolymers lowered the surface tension of water in analogy with the low molecular weight surfactants such as sodium lauryl sulfate and heptaethylene oxide n-dodecyl ether. Their aqueous solutions exhibited solubilization properties differing from those of polyethylene glycol. Therefore, it is thought that the polystyrene blocks produce solubilization phenomena. In samples of the same styrene content, the precipitation temperature of a high molecular weight copolymer in water was lower than that of a low molecular weight copolymer at the same concentration in the same solvent. The surface tension and precipitation temperature of aqueous solutions seem to be influenced by molecular weight and composition.
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  • 113
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1317-1324 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A weak acid gel (carboxylmethyldextran) was titrated with sodium hydroxide while equilibrated with a solution sodium poly(vinyl sulfate), a salt of a strong acid polyelectrolyte.It was found that the quantity \documentclass{article}\pagestyle{empty}\begin{document}$$ S = {\rm pH} - {\rm pNa} + \log (V/V_0) $$\end{document} in which V/V0 is the volume of gel relative to its volume in acid form in pure water, is independent of the concentration Cp of the polyelectrolyte solution and of the relative volume of gel.The relation \documentclass{article}\pagestyle{empty}\begin{document}$$ S - \log \left({\frac{{\alpha ^2}}{{1 - \alpha}}} \right) = {\rm pK'} + \log \gamma _{{\rm Na}}^{\rm g} + \log (v/V_0) $$\end{document} where α is the degree of ionization, pK′ is the apparent pK of the gel, γnAG is the activity coefficient of the counterion in the gel phase, and v is the number of ionizable groups, is found to be constant for all values of Cp and for 0.1 〈 α 〈 0.9. These results can be extended to highly crosslinked ionexchange resins.
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  • 114
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1647-1654 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The infrared spectra of polyethylene single crystals suspended in liquid are reported and compared to dried mats of the same material. In order to observe the polyethylene bands, liquids with partial windows in complementary regions of the spectra were chosen. Any remaining bands of the suspending media were removed by substraction of the spectrum of the pure liquid. The crystalline bands of suspended polyethylene are much sharper than those of the dried material, indicating a decrease in lateral crystalline order upon drying. Drying also results in a change in the type and distribution of conformations associated with amorphous and fold structures, as determined by the observed frequencies of the methylene wagging mode.
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  • 115
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1675-1683 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal behavior of films of amorphous silk fibroin in the random-coil conformation has been investigated in the temperature range 25-220°C by differential scanning calorimetry (DSC), thermal expansion, dynamic mechanical measurements, x-ray diffraction, and infrared spectroscopy. As the temperature is raised, water is lost up to about 100°C. Intramolecular and intermolecular hydrogen bonds are broken between 150 and 180°C. The glass transition is observed at 173°C by DSC. The random-coil→β-form transition accompanied by reformation of hydrogen bonds takes place above 180°C. Thermally induced crystallization to the β-form crystals starts at about 190°C.
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  • 116
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1757-1767 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: From glass transition Tg measurements on isotactic polystyrene (IPS)-poly(2,6-dimethyl phenylene oxide) (PPO) blends, it was concluded that thoroughly annealed, freeze-dried samples, or samples evaporated from solution at high temperature, are homogeneous. Without annealing, the freeze-dried blends show two to three Tg's characteristic of the presence of different phases. The overall crystallization rate of these samples is much higher than that observed with annealed samples. The presence of dissolved PPO in annealed samples reduces the overall crystallization rate and the spherulitic growth rate, compared to IPS. The melting behavior of the blends is influenced by the extent of mixing of both polymers. Without annealing, isothermally crystallized, freeze-dried blends show the same melting behavior as IPS (i.e., multiple melting). In homogeneous annealed samples the rate of reorganization is strongly reduced and multiple melting only occurs at low scanning rate (e.g., 1°C/min). This behavior is influenced by the crystallization temperature and by the composition of the blends. The addition of PPO has no influence on the relation between melting point and crystallization temperature and the same equilibrium melting point is found by extrapolation.
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  • 117
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1837-1861 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Energy-deformation characteristics for the primary T, S, and U conformational units of tie molecules were obtained from the analysis of data generated from a constrained minimization algorithm. Energy-deformation profiles (covering the range from compact equilibrium defect structures to the fully extended chain) are reported for the S0 and S1 members of the Sλ family and for the U00 member of the Umn family. Estimates of the energy content V0 and the elastic modulus E were obtained from the computed energy-deformation data in the vicinity of the equilibrium Structure - S0 → {60°, 180°, -60°}, V0S0 = 1.7 kcal/mole, ES0 = 60 kcal/cm3 [250 × 1010 dyn/cm2];S1 → {60°, 180°, 180°, 180°, -60°}: V0S0 = 1.7 kcal/mole, ES1 = 25 kcal/cm3 [100 × 1010 dyn/cm2]; and U00 → {60°, 180°, 60°, 180°, 60°}: V0U00 = 2.7 kcal/mole, EU00 = 80 kcal/cm3 [340 × 1010 dyn/cm2]. Although the elastic modulus of the U00 unit is comparable to the elastic modulus of the fully extended chain, the highenergy content of this unit (V0 = 2.7 Kcal/mole) prohibits a significant population and thereby mitigates an appreciable reinforcing effect from this rigid unit. A model for a surrogate force constant is introduced to generalize the results from this study to any member of the Sλ or Umn family as well as any combination of Sλ and Umn units. This generalization provides a basis for estimating the deformation characteristics of tie molecules comprised of various populations of these primary conformational building blocks.
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  • 118
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1913-1925 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ultraviolet and Fourier-transform infrared spectroscopy are used to characterize the chain conformation of 2,6-dimethyl poly(phenylene oxide) (2MPPO) in compatible 2MPPO-polystyrene (PS) blends. Blending with PS increases the intramolecular energy of the 2MPPO. Atactic PS induces a greater distortion from the minimum energy conformation of 2MPPO than isotactic PS. The dispersion interaction between the phenyl ring of PS and the phenylene ring of 2MPPO is found to be quite strong. These large intermolecular forces are thought to supercede the increase in 2MPPO conformational energy and to be responsible for the blend compatibility.
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  • 119
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1967-1982 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The intensity of the water-induced γ relaxation (see ref. 1) in crosslinked polyester networks in creases rapidly at low water concentrations (0 to 0.5% by weight). At higher water concentrations (0.5 to 3.0%) the intensity of the γ relaxation approaches a constant value. The shift of the relaxation peak to lower temperatures shows a similar pattern of behavior. These results have been related to the fraction of water involved in the relaxation and the changing nature of the relaxation sites with the increase in water concentration. The important role that fumarate units play in the γ relaxation has also been confirmed; however, the chemical nature of the relaxing unit appears to be more complex than was originally considered. Two models are proposed for this behavior.
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  • 120
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2027-2031 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 121
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2037-2038 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 122
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2055-2056 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 123
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2087-2093 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Interactions of water-soluble AB block copolymers of polystyrene and poly(ethylene oxide) with sodium lauryl sulfate (SLS) in aqueous solution were investigated by high-resolution proton magnetic resonance (NMR). The viscosity in aqueous SLS solution was also measured. From the NMR results in D2O, it appears that molecular motions of the polystyrene blocks of the copolymer in aqueous solution are activated by interaction between the polystyrene blocks and the added SLS. From solution viscosity, on the other hand, it is apparent that a complex is formed between the copolymer and SLS and that it exhibits typical polyelectrolyte properties. The polyelectrolyte character is attributable largely to intrachain repulsions between like charges of the SLS anions adsorbed on the poly(ethylene oxide) blocks of the copolymers since the polystyrene blocks are insoluble in water and the styrene content is less than 10%.
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  • 124
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2127-2142 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spin-lattice 1H and 13C nuclear magnetic relaxation (NMR) times T1 have been measured for solutions of polystyrene in hexachlorobutadiene at two different frequencies. Some nuclear Overhauser enhancements and linewidths have also been determined. At 15 and 25 MHz the relaxation times T1 of the ortho and meta carbons show two different dependences on temperature. These measurements indicate internal motion of phenyl groups around the Cα - Cpara axis. A single isotropic correlation time is inadequate to explain the relaxation data for the para carbon. Use of a diamond-lattice motional model reveals that segmental reorientation of the chain backbone of polystyrene can be described in terms of two correlation times, ρ characterizing the three-bond motion process, and θ reflecting either isotropic motions of subchains or departure from an ideal lattice. Data on low-molecular-weight polystyrene indicate the participation of overall rotatory diffusion in the relaxation process. This motion is no longer efficient in high-molecular-weight polymers, where relaxation is due to segmental reorientation.
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  • 125
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    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2185-2199 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Biaxial and uniaxial tensile stress relaxation tests were made on square sheet specimens of styrene butadiene rubber (SBR), mounted in a universal biaxial tester within a temperature-controlled box, with the object of studying the effect of temperature on the strain energy function. The stress relaxation responses, usually for times up to 10 min, were obtained for various degrees of biaxiality, various extension ratios, and various temperatures within the limits of +25 to -45°C. The results indicated that if the Valanis-Landel representation of the strain energy function \documentclass{article}\pagestyle{empty}\begin{document}$ W = \sum\nolimits_{i = 1}^3 {w\left( {\lambda _i } \right)} $\end{document} is adopted, then time and strain are factorizable over the indicated temperature range, with time and temperature being related in the usual fashion. That is, changing the temperature does not affect the form of w(λi) but only that of G(t/αT), the temperature-dependent relaxation modulus, aT being the regular Williams-Landel-Ferry (WLF) shift factor. The results verify the Valanis-Landel theory for various combinations of biaxiality
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  • 126
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 387-394 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is proposed that bending of solution-grown polymer crystals causes the observed diffraction line-broadening in many cases. Independent estimates and observations of the severity of bending which can be sustained are used to calculate corresponding apparent crystal sizes, where the apparent crystal size is that obtained when it is assumed that broadening is caused by the small crystal size effect only. Bending broadening is found to be of sufficient magnitude to produce the observed broadening reported in the literature. Some of the steps taken so far in the development of line-broadening analysis for polymer crystals show similarities with the evolution of line-broadening analysis for graphitic carbons and a brief review of the latter is included.
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  • 127
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 431-441 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solid-state synthesis and properties are reported for a new polydiacetylene: poly[1,6-di(N-carbazolyl)-2,4-hexadiyne]. The monomer crystals polymerize quantitatively with γ irradiation or thermal annealing. An Autocatalytic effect is observed in both γ-ray polymerization and thermal polymerization and is attributed to an increase in chain propagation length at about 5% conversion. The activation energy for thermal polymerization is about 25 kcal/mole, independent of the degree of conversion to polymer. The exceptional thermal stability of the polymer crystals allowed a thermomechanical analysis over a large temperature range, -50 to 300°C. With increasing temperature, the polymer contracts in the chain direction linearly with temperature over the entire range, yielding a thermal expansion coefficient of (-2.32 ± 0.02) × 10-5°C-1. Photoconductivity action spectra are reported for the polymer crystals. The energies for the photoconductivity onset (ca. 2.3 eV) and for the lowest energy optical transition (1.89 eV) are the lowest reported for the polydiacetylenes. The photoconduction onset is blue-shifted with respect to optical absorption - a result which is consistent with the excitonic assignment for the lowest energy optical transition in the polydiacetylenes.
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  • 128
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 485-500 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Macromolecular chain rupture occurring during tensile deformation of semicrystalline polymers has been investigated by measuring changes in the viscosity-average molecular weight. When interpreted in terms of a random-scission scheme, the observed changes in molecular weight correspond to chain rupture concentrations β ≈ 1018/cm3 for high strength nylon and poly(ethylene terephthalate) fibers. Polypropylene fibers and isotropic samples of polyethylene, polypropylene, and nylon 6 had β ≈ 1016/cm3. The effects of stretching environment and thermal and mechanical history were noted. In all cases, the present study indicated bond rupture concentrations about 10 times larger than those obtained from electron spin resonance (ESR) experiments. The relation between viscometry, ESR, and infrared (IR) estimates of bond rupture and their relevance to mechanical properties are considered.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 529-543 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The piezoelectric effect in films of polyvinylidene fluoride (PVF2) is investigated using optical and ultrasonic detection techniques. From the analysis of the vibrational resonance frequencies of a freely suspended film we conclude that the polarization induced in PVF2 is inhomogeneous across the volume of the sample. Poling the foils in a sandwich configuration or using blocking electrodes, we can clearly demonstrate that the piezoelectric effect in PVF2 originates from the positive metal electrode. Monitoring the time dependence of the piezoelectric effect during the poling process, a fast and slow component are observed. Using a blocking electrode, however, the same dynamical poling behavior is found only if the contacting metal electrode is positive. In view of these observations, which clearly demonstrate the importance of the metal-polymer interface for the strong piezoelectricity of PVF2, the existing theoretical models, based on the bulk properties of the polymer, are critically reviewed.
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  • 130
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 501-511 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A previous study of poly(ethylene oxide) (PEO) in aqueous salt solutions has been extended to incorporate cloud-point measurements in potassium thiocyanate solutions (salt concentration range 3.3-3.8M where salting out occurs) and, particularly, viscosity measurements. A few osmoticpressure measurements were made and molecular weights (∼2 × 104) from gel-permeation chromatography (GPC) compared. The theta temperature for PEO in water from cloud points was found to be 369 ± 3°K. An empirical linear relation has been found for sodium and potassium salts between the finite change of theta temperatures with change in ionic strength, δθ/δI, and (v3 - v̄3), the difference between the molar van der Waals volume and the partial molar volume of the salt. Values of the Huggins constant k′ are less than 0.5 for PEO in pure water at 303.2°K, indicating a good solvent, whereas in salt solutions they vary from 0.59 to 1.14 in nontheta solvents. They and other findings are attributed to binding of salt to the polymer and to water structure breaking. Kraemer's constants k″ were also determined: k′ - k″ = 0.5 for PEO in pure water, and for aqueous salt solutions of PEO, k′ - k″ = 0.666 at 298°K. Values of K0(= M-1/2[η]θ) with M = 2 × 104 were found to very with salt type (valence) - mean values of 103 K0/dlg-1 with number of observations in brackets are 1:1, 1.19 (2); 1:2, 1.45 (3); 2:2, 1.75 (3). Unperturbed dimensions 〈r2〉01/2 vary from 11.0 to 12.6 nm from 1:1 to 2:2 salts. Values of the characteristic ratio Cn, the steric parameter σ, and the enthalpy and entropy of dilution parameters χH and χS have also been calculated.
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  • 131
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 159-169 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phenylmercurated poly(ethylene terephthalate) (PET) chain-ends are obtainable through the transesterification of PET by phenylmercury hydroxide or acetate in solution in nitrobenzene at 165 ± 10°C. The reaction results in an average of one mercury atom per chain. The phenylmercuration may be followed by infrared or x-ray fluorescence. Reaction with concentrated HCI Affords the elucidation of some structural parameters of the resultant partially crystalline tagged PET, through analyses of changes in viscosity and molecular weight, in percent crystallinity, and in the amount of mercury in the system. The chain-ends are almost completely excluded from the stem region of the PET crystal with no more than 2% remaining. The chain-ends are distributed unevenly throughout the amorphous phase. This is corroborated by sharp decreases in scattered intensity of small-angle x-ray measurements. Two models for the distribution of chain-ends in the amorphous phase are considered. The one in which the ends are pushed farthest from the crystal surface and concentrate halfway between crystallites is tentatively adopted. Analysis of the HCI hydrolysis kinetics and products leads to the following picture concerning the fold tightness and position. About one out of five folds extends significantly into the amorphous matter where it is mingled with cilia, tie molecules, and unattached molecules. Random scission throughout such an amorphous mass should lead to a preponderance of cleaved molecules whose length should be four to five times the lenght of the crystalline stem region, as is indeed observed.
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  • 132
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1891-1901 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A nonisothermal creep experiment has been analyzed to ascertain its suitability for determining the temperature dependence of low activation energy viscoelastic processes in elastomers far above Tg. The nonisothermal method was employed to determine the activation energy for creep near 35°C in a lightly crosslinked cis-1,4 polybutadiene elastomer at small strains within the linear viscoelastic region, and at various large deformations up to rupture. The observed activation energy was essentially independent of the level of strain, and the value of ΔHa (∼11 kcal/mole) determined via the nonisothermal creep method was in good agreement with the result (∼12 kcal/mole) obtained via time-temperature superposition of isothermal linear viscoelastic creep data. The nonisothermal data allowed for an estimate of the volume of the “flow unit” associated with the controlling viscoelastic creep mechanism, attributed here to slippage of entanglements within the lightly crosslinked network.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1877-1890 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric relaxation and Brillouin scattering are jointly used in studying molecular relaxation in poly(propylene oxide) (PPO) and its solutions in methylcyclohexane. The dielectric method was applied to the more concentrated (100%, 80%, 60%, by volume) solutions over a wide temperature and frequency range (30 Hz to 8 GHz) in order that the variation in activation energy characteristic of a glass-forming substance could be delineated. The present work extends previous work on the undiluted polymer to higher frequencies so that range of 12 decades in the dielectric loss maximum fmax as a function of temperature is now available. The “Antoine” equation is found to represent the behavior of log fmax, of the bulk concentrated solutions very well. The more dilute (40%, 20%) solutions were studied only in the high-frequency (GHz) region since phase separation occurred at low temperatures. Both the temperature and dilution effects were interpreted in terms of free-volume theory. Brillouin scattering spectra were obtained at several scattering angles and a wide range of temperatures. A maximum in the curve of hypersonic attenuation versus temperature was observed in each polymer solution. The attenuation maximum shifts toward lower temperature upon dilution, in agreement with the dielectric relaxation result. The Brillouin scattering follows different activation parameters and evidences a more rapid process than does the dielectric relaxation. It is speculated that it monitors a secondary or subglass relaxation, due perhaps, to damped torsional oscillations.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 759-766 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Characterization measurements of a commercial phenol-formaldehyde resin prepared from constituents including phenol and formaldehyde in the molar ratio 1:1.33 are reported. The measurements consist of (1) the linear thermal expansion coefficient between approximately 85 and 270°K; (2) the specific heat capacity between approximately 6 and 100°K; (3) the Young's modulus at room temperature. A critical examination of the data reveals that: (1) the vibrational behavior is predominantly that of a three-dimensional assembly; (2) as far as data available from other sources permit an assessment to be made, the principle of additivity appears to be applicable to the specific heat capacity between approximately 50 and 100°K; and (3) the data lie near the limit of an empirical relationship observed between the Young's modulus and linear thermal expansion coefficient of other polymers.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 427-430 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Radiothermoluminescence has been used to show that the surface of latex globules in nonvulcanized latex films contain segments which become mobile at a temperature 20°K below that observed in bulk polymer. Vulcanization in latex films takes place mainly on the surfaces of the latex globules; vulcanized latex films are microheterogeneous systems.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 457-466 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Smoluchowski formalism is used to solve the problem of a bead of frictional resistance β attached to a surface with a spring of force constant k over which a linear shear field of strenght α flows. The power dissipation is given by βα2kT/k. k and T have their usual meanings. The result is generalized to an n-bead polymer. It is found that the power dissipation of a Rouse model polymer attached to a surface at one end is twice that of an identical polymer flowing freely in solution. If the force constant k arises from an entropy force, then, because of the effect of the surface on the number of polymer configurations, there is an additional factor of two. The same relationship is expected to also hold for the frequency-dependent power dissipation. It is argued that a net circulation exists in the beads above the surface and that the magnitude of the circulation is roughly comparable to that which exists in a polymer freely rotating in solution under a shear field of the same magnitude.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 523-528 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By measurement of integrated intensities of high-resolution proton nuclear magnetic resonance (NMR) bands, associated structures of isotactic (i) and syndiotactic (s) poly(methyl methacrylate) (PMMA) in dilute toluene-d8 and dimethylformamide-d7 solutions were detected and characterized. In 1% (w/v) solutions of highly stereoregular s-PMMA in toluene-d8 at 27°C, 76% of the monomer units are present in the form of compact aggregates. Consequences of this finding for the polymerization of methyl methacrylate in toluene in the presence of s-PMMA are discussed.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 555-564 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A theory of variability in lifetimes of identical polymer specimens under identical test conditions is formulated, using the theory of fracture of amorphous crosslinked polymers developed previously by the authors. Variability in fracture times follows from the assumption that the critical number Ncr of bonds that must fail in order to cause fracture of a specimen varies from specimen to specimen. A plausible physical explanation for the variation in Ncr may well lie in the variability of the spatial distribution of weak local regions. The scale of locality may vary from molecular to grosser dimensions. The theory is applied to styrene-butadiene rubber (SBR) under creep conditions and fares well in its prediction of observed results. Most notably, it predicts that the shape of the distribution curve of the observed lifetimes remains invariant with changes in the levels of stress and temperature and that the effects of these manifest themselves through shifts of the curve on the logarithmic time axis. The theory also predicts correctly that the fracture process is accelerated if the creep test is interrupted by unloading-reloading cycles at high strain rates. This last result is shown to be a direct consequence of the concept of “the endochronic time to fracture,” previously introduced by the first author.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 599-612 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Morphological changes accompanying the deformation of polypropylene filaments with varying degrees of melt-induced orientation are examined using wide-angle x-ray scattering (WAXS), small-angle x-ray scattering (SAXS), and electron microscopy, and their behavior is compared both to completely unoriented film samples and to very highly oriented, hard elastic filaments. Melt-oriented filaments are shown to deform predominantly by a voiding mechanism at low temperatures (〈100°C), and destruction of the lamellas to produce fibrils occurs only after extensive drawing. The bimodal crystal texture of the filaments does not appear to greatly affect the low temperature deformation mechanism. High temperature (〉100°C) drawing produces a fibrillar structure containing elongated voids.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 667-678 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three of the Poisson's ratios have been measured on a low-density polyethylene (LDPE) sheet with parallel lamellas morphology over the temperature range from +20 to -60°C. The measurements were carried out using a specially constructed lateral extensometer which utilized the Hall effect to detect the very small strains involved. The Poisson's ratios show considerable temperature dependence, and at high temperature the overall deformation approximates to pure shear as previously noted. It is suggested that this relates to the onset of the c-shear relaxation.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 1297-1319 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The load-elongation behavior during the postneck drawing stage in the deformation of crystalline polymers is shown to be modeled quantitatively by an aligned short-fiber composite in which crystalline fibrils form the reinforcing phase in a matrix of less well-ordered material. Three modes of deformation are distinguished in the model and are shown to correspond to the observed loadelongation relations in polyethylene and polypropylene. The regions are (I) elastic-plastic crystals in an elastic matrix, (II) elastic-plastic crystals in an elastic-plastic matrix, (III) elastic crystals in an elastic-plastic matrix. A requirement of the theory is that the flow stress in the crystals is little affected by temperature whereas that in the matrix falls as the temperature rises. Expressions are given for stress in terms of the applied strain and the relevant parameters of the system: concentration of fibrils, length and diameter of fibrils, and elastic and yield properties of fibrils and matrix.
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    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 1365-1379 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The four-center solid-state photopolymerization of distyrylpyrazine (DSP) and of 2,6-naphthalene bis(acrylic acid-2,4-dichloro phenyl ester) (NBA-DCP) was investigated by x-ray and microscopic techniques. In both cases the polymer grows as a separate product phase topotactically well arranged with respect to the monomer matrix. In the case of polymerization of DSP the space group of the monomer (Pbca) is not maintained but the polymer phase has space group P21ca. Nucleation and growth of the polymer phase was observed by light and electron microscopy. Nucleation occurs at defect sites. The polymer grows at different rates in different crystallographic directions which were identified by electron diffraction in the case of DSP. Polymerization thus occurs in the transition region between monomer crystal and product phase and not in the bulk of the crystal so that the four-center-type photopolymerization is best described as a heterogeneous solid-state reaction.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 361-367 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Freeze-dried single crystals of unfractionated Marlex 6009 polyethylene were irradiated at various doses up to 100 Mrad. Analysis of the data of the present work and those of others showed that the decay of vinyl groups can be best described by second-order kinetics. The decay rate constant is found to increase with decrease in original concentration of vinyl groups. It has been concluded that the increase in the decay rate constant with decrease in initial vinyl concentration is due to a decrease in crystallinity. Some supporting evidence has been presented for this conclusion.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 863-869 
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    Keywords: Physics ; Polymer and Materials Science
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 889-899 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 13C NMR configurational assignments are made for an amorphous polystyrene sample examined at 25.2 MHz and 120°C. The assignments are based strictly on a one-parameter Bernoullian fit that was in satisfactory agreement with the nine observed methylene relative intensities. The methylene regions of the 13C NMR spectra of a polystyrene were examined before and after hydrogenation of the side-chain phenyl substituents. It was concluded that ring current effects have influenced the 13C methylene chemical shifts substantially and are limited largely to contributions from adjacent phenyl substituents. In addition, aromatic substituent parameters are reported that can be used in conjunction with the Grant and Paul parameters for calculating chemical shifts in aromatic hydrocarbons and polymers. Finally, it is concluded that free-radical and n-butyllithium-prepared polystyrenes have essentially atactic structures with meso additions favored over racemic additions by approximately 55/45.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 947-951 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the glass-rubber transition region of viscoelastic behavior of amorphous polymers, it is found that \documentclass{article}\pagestyle{empty}\begin{document}$$J\left( {\rm t} \right) \approx J''\left( {1/t} \right)$$\end{document} is a good first approximation. Here J(t) is the value of the shear creep compliance at time t and J″(1/t) is the value of the shear loss compliance at an angular frequency of 1/t. Previous approximations related the creep compliance to the storage compliance. When J(t) is proportional to tm, where m is a positive constant, J″(1/t) is within 30% of J(t) for m 〉 0.6. Over the entire range, \documentclass{article}\pagestyle{empty}\begin{document}$$ J\left( t \right){\rm } \approx {\rm }J_{\rm d} \left( {{1 \mathord{\left/ {\vphantom {1 t}} \right. \kern-\nulldelimiterspace} t}} \right) $$\end{document} is a better approximation than either of the other two. The relaxation modulus G(t) is hardly ever a good approximation for the loss modulus G″(1/t).
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 971-975 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An adiabatic heat capacity study of poly(diethylsiloxane) confirms that it has a single glass transition occurring at 130°K, the lowest glass transition reported to date for a high molecular weight polymer. The two previously reported glass transitions are first-order thermodynamic peaks whose location is dependent upon prior thermal history. Combination of these data with low-temperature x-ray diffraction indicates that the transitions in this temperature range are related to a crystal-crystal transformation. A crystal melting transition is observed near 270°K. In addition an anomalous rise in heat capacity near 60°K suggests a sub-glass transition of unknown origin.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1023-1032 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Interferometric studies of the diffusion of molecular iodine into polyvinylpyrrolidone (PVP) are described. The diffusion process is observed by means of a holographic microscope which, with a camera, permits holograms to be recorded during the polymer-iodine interaction. The holograms are subsequently used to produce interferograms that monitor the diffusion process as a function of time. Measurements taken from the interferograms indicate that the diffusion mechanism is not purely Fickian and that the diffusing boundary of iodine is characteristic of case II diffusion. The interferograms yield values for average diffusion coefficients as a function of sample thicknesses that range from 2.32 to 9.53 × 10-10 cm2/sec.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 825-834 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: EPR and matrix ENDOR spectra have been examined for polyenyl radicals in γ-irradiated PVF, PVF2, PVC, and PMMA polymers. Proton matrix ENDOR is observed for all four polymers, and fluorine matrix ENDOR for PVF and PVF2. By line shape analysis of the ENDOR spectra obtained under comparable conditions, delocalization diameters for the unpaired electron of the polyenyl radical in each polymer are obtained. These diameters indicate extensive delocalization over 5-7 carbon double bonds for the polyenyl radicals investigated. It is suggested that these conjugated and crosslinked radiation products account for the observed nondevelopment of electron beam resist PMMA material at high radiation charge densities.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 835-850 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A systematic study of the dispersion curves of the refractive indexes of nylon 6 yarns was made. The parameters were the draw ratio and strain. The measurements show that the dispersions of the refractive indexes n∥ and n⊥, parallel and perpendicular to the fiber axis, are equal, independently of draw ratio and strain. The average dispersion equals nF - nC = 109 × 10-4. Consequently, the birefringence is, within experimental accuracy, independent of the wavelength. The refractive indexes and the birefringence show a change in trend at 10-12% strain. This point corresponds to the yield strain in the stress-strain diagrams. The inference is that beyond the yield point the overall molecular orientation must increase less strongly with strain than before. An analysis shows that the Lorentz-Lorenz relation holds for the average refractive index n̄ = ⅓ (n∥ + 2n⊥). So the change in n̄ versus draw ratio is mainly due to the change in density. By applying the Lorentz-Lorenz relation to the change of n̄ on straining, a value of Poisson's ratio (μ) could be derived. The average value found for nylon 6 yarns was μ = 0.48, which means that the density hardly changes with strain.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 901-908 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Improvements in the 13C NMR Grant and Paul parameters as applied to polymers have been obtained by noting that the “corrective terms” can be temperature-sensitive. A corresponding temperature sensitivity was not observed for the primary parameters, α through ∊. Results are given for a hydrogenated polybutadiene and six different ethylene-1-olefin copolymers where the standard deviation between calculated and observed chemical shifts has been improved from 1.04 to 0.30 ppm. Since the “corrective terms” in the Grant and Paul empirical analyses of chemical shifts reflect the conformational character of polymers, it is shown that values for these terms can best be obtained directly from the system under study.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1097-1113 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: After flowing in a dilatometer bulb for a small fraction of the duration of the transformation, a relaxed melt of poly(ethylene oxide) (M̄n = (5.9 ± 0.1) × 103) showed marked increases in isothermal crystallization rate. The extent of increase was greater when flow was imposed at modestly later stages rather than at the earliest stage of a crystallization. Kinetic parameters for the flow-induced crystallizations were obtained via modification of the conventional mathematical treatment of the kinetics of phase change, thereby allowing the analytical resolution of the overall process into flowinduced and quiescent components. Determination of the flow-induced crystallization parameters required independent determination of the kinetic parameters for quiescent crystallizations at that temperature. The Avrami exponents nf which characterized the flow-induced portions of the crystallizations were larger for those instances in which flow was imposed at the more advanced stages of the crystallizations, thus indicating a transition in crystallization mechanism. It is suggested that prior crystallinity present at the time of flow contributed to the crystallization by serving as a source of nucleation sites. However, in light of the experimental procedure employed, values of nf approximating 4 that were obtained are not susceptible to mechanistic interpretations now extant.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1159-1166 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fundamental vibrational frequencies of an isolated chain of trans-1,4-polychloroprene have been calculated. The agreement between the calculated and experimentally observed crystalline frequencies supports the molecular model for the structure of trans-1,4-polychloroprene and the force field employed in the calculations. The results of the normal coordinate analysis indicate that there is essentially no coupling between adjacent translational repeat units of trans-1,4-polychloroprene.
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  • 154
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1201-1214 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experiments were designed to demonstrate that the chemical potential gradient required for liquid transport through swollen network polymer membranes manifests itself as a concentration gradient and that the rate of transport is independent of how this gradient is established. The fluxes of various liquids through a crosslinked rubber membrane were measured in hydraulic and pervaporation modes of permeation. The pressure applied downstream in the latter act simply to fix the activity of the liquid in the downstream membrane surface. The experiments show the flux is a unique function of this activity, and it does not matter how it is established. Sorption data were used to convert these results into a plot of flux versus concentration differential across the membrane which was analyzed by Fick's law using a model for the concentration dependence of the diffusion coefficient. Measured ceiling fluxes for pervaporation for a number of liquids were found to be the same as those estimated from hydraulic permeation data. A simple mathematical representation for an ideal system is used as a pedagogical device to demonstrate the conclusions.
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  • 155
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1533-1542 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low molecular weight PVC polymers of known degree of crystallinity (44% by x-ray diffraction), prepared in the presence of the chain-transfer agents n-butyraldehyde and n-butyl mercaptan, are examined by differential scanning calorimetry in order to ascertain temperatures and heats of fusion. Initial thermal scans are accompanied by large endotherms and appreciable weight losses due to the lability of the terminal groups originating from the chain-transfer agents. However, further successive scans result in approximately invariant endotherms attributable to crystalline fusion. The maximum melting point, about 265°C, exceeds the value for commercial PVC, about 210°C, but is lower than a value deduced for a hypothetical completely syndiotactic polymer, about 400°C. The average heat of fusion ΔHu is 1180 ± 90 cal/mole, and the resultant entropy of fusion is 1.1 cal/deg/bond. The present ΔHu value differs significantly from previously reported values of 660-785 and 2700 cal/mole, based on melting point depression theory, but appears to be concordant with known heats for a series of vinyl polymers.
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  • 156
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1563-1576 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Strain-dependent relaxation moduli G(t,s) were measured for polystyrene solutions in diethyl phthalate with a relaxometer of the cone-and-plate type. Ranges of molecular weight M and concentration c were from 1.23 × 106 to 7.62 × 106 and 0.112 to 0.329 g/cm3. Measurements were performed at various magnitudes of shear s ranging from 0.055 to 27.2. The relaxation modulus G(t,s) always decreased with increasing s and the relative amount of decrease (i.e.,-log[G(t,s)/G(t,0)]) increased as t increased. However, the detailed strain dependences of G(t,s) could be classified into two types according to the M and c of the solution. When cM 〈 106, the plot of log G(t,s) versus log t varied from a convex curve to an S-shaped curve with increasing s. For solutions of cM 〉 106, the curves were still convex and S-shaped at very small and large s, respectively, but in a certain range of s (approximately 3 〈 s 〈 7) log G(t,s) decreased rapidly at short times and then very slowly; a peculiar inflection and a plateau appeared on the plot of log G(t,s) versus log t. The strain-dependent relaxation spectrum exhibited a trough at times corresponding to the plateau of log G(t,s). The longest relaxation time τ1(s) and the corresponding relaxation strength G1(s) were evaluated through the “Procedure X” of Tobolsky and Murakami. The relaxation time τ1(s) was independent of s for all the solutions studied while G1(s) decreased with s. The reduced relaxation strength G1(s)/G1(0) was a simple function of s (The plot of log G1(s)/G1(0) against log s was a convex curve) and was approximately independent of M and c in the range of cM 〈106. This behavior of G1(s)/G1(0) was in agreement with that observed for a polyisobutylene solution and seems to have wide applicability to many polymeric systems. On the other hand, log G1(s)/G1(0) as a function of log s decreased in two steps and decreased more rapidly when M or c was higher. It was suggested that in the range of cM 〈 106, a kind of geometrical factor might be responsible for a large part of the nonlinear behavior, while in the range of cM 〉 106, some “intrinsic” nonlinearity of the entanglement network system might be important.
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  • 157
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1591-1602 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Composites with a matrix of poly(2-hydroxyethyl methacrylate) (PHEMA) and 10% by volume of various crosslinked PHEMA polymer fillers (prepared by copolymerization with 0.1, 0.4, 1.0, and 20.0% by weight of ethylenedimethacrylate) of particle size about 1 μm were prepared. Some polymer matrixes were prepared from soluble branched PHEMA (Hydron S), and others by copolymerization, in the presence of the filler with 0.4 and 1.0% of ethylenedimethacrylate as a crosslinking agent. In the case of the uncrosslinked matrix, a linear polymer-crosslinked polymer system, resulted; in the case of the crosslinked matrix, a composite heterogeneous network was formed (in the latter case, the particles of the filler were swollen with monomer during the crosslinking polymerization).Stress-strain, equilibrium, and ultimate characteristics were measured at 3, 10, 25, 40, 60, and 80°C on samples swollen to equilibrium in water (Tg ≈ -50°C) and at 80, 110, and 140°C on dry samples (Tg ≈ 100°C). Depending on experimental conditions, above all on the distance from the main transition region and on whether the polymer is dry or swollen, it was found that the measured hydrophilic composite systems behaves as a filled system (with the polymer filler acting mostly as solid particles, irrespective of the crosslink density) or as a system with crosslink density fluctuations (where both networks, the matrix and the filler, contribute roughly additively to the properties of the system), or finally as defect heterogeneous systems (where the properties depend primarily on the character of the polymer-filler interface).
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  • 158
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1577-1589 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The steady shear viscosity η(k) and the stress decay function \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \eta \left({t,k} \right)$\end{document} (the shear stress divided by the rate of shear k after cessation of steady shear flow) were measured for concentrated solutions of polystyrene in diethyl phthalate. Ranges of molecular weight M and concentration c were 7.10 × 105 to 7.62 × 106 and 0.112-0.329 g/cm3, respectively. Measurements were performed with a rheometer of the cone-and-plate type in the range 10-4 〈 k 〈 1 sec-1. The Cox-Merz relation η(k) = |η*(ω)|ω=k was tested with the experimental result (|*(ω)| is the magnitude of the complex viscosity). It was found to be applicable to solutions of relatively low M or c but not to those of high M and c. For the latter η(k) began to decrease at a lower rate of shear than |η*(ω)|ω=k did; the Cox-Merz law underestimated the effect of rate of shear. The stress decay function was assumed to have a functional form \documentclass{article}\pagestyle{empty}\begin{document}$\tilde \eta \left( {t,k} \right) = \sum {\eta _p \left( k \right)e^{ - t/\tau p\left( k \right)} } $\end{document} where τ1 〉 τ2 〉 …, and the values of τ1, τ2 η1 and η2 were determined for some solutions. The relaxation times τ1 and τ2 were found to be independent of k and equal to the relaxation times of linear viscoelasticity. At the limit of k → 0, η1 and η2 were approximately 60 and 20-30%, respectively, of η and the non-Newtonian behavior was due to large decreases of η1 and η2 with increasing k. It was shown that η1(k) may be evaluated from the relaxation strength G1(s) for the longest relaxation time of the strain-dependent relaxation modulus with a constitutive model for relatively high c-M systems as well as for low c-M systems.
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  • 159
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1633-1642 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of five heterogeneous network polymers was prepared from poly(D-glutamic acid) (PDG) and poly(oxyethylene glycol) (PEG), and their dynamic mechanical properties were studied. The content of PDG was fixed at 60% by weight, and the molecular weight of PEG was changed to obtain networks with various crosslink densities. An increase in the PEG molecular weight from 330 to 880 caused considerable broadening of tan δ and E″ curves, and peak temperatures for tan δ and E″ decreased slightly. Curves of tan δ and E″ for PDG-PEG 4000 (indicating a PEG component of molecular weight 4,000) were much broader and the existence of two peaks was recognized. These findings and x-ray photographs suggest that PDG-PEG 330, 570, and 880 give films of fairly uniform phase, but that PDG-PEG 1830 and 4000 give films with two-phase structure. The factors influencing the dynamic mechanical properties in decreasing order of effectiveness are found to be the proportions by weight of PDG and PEG, the compatibility of PDG with PEG, the crosslink density, and the concentration of free carboxyl groups. The infrared spectra of these polymers indicate that at least part of the PDG component retains the α-helix conformation.
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  • 160
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Mixtures of crosslinkable ethylene-propylene terpolymer with saturated ethylene-propylene copolymer (molecular weights 3.6, 16.7, and 45 × 104) containing up to 50% by weight of copolymer were crosslinked by sulfur, leaving the saturated copolymer unattached and free to reptate in the terpolymer network. Stress relaxation in small simple elongations (stretch ratio about 1.15) and dynamic Young's modulus at frequencies from 3.5 to 110 Hz were measured at temperatures from 10 to 50°C. Comparison with the properties of the terpolymer crosslinked without added copolymer showed contributions to stress relaxation and mechanical loss attributable to the unattached species. The time required in stress relaxation for the portion of the modulus attributable to the unattached species to decay to half its plateau value, t1/2, is approximately proportional to the 3.5 power of the molecular weight; t1/2 appears to be slightly smaller for networks containing 50% than for those containing 25% unattached component.
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  • 161
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1721-1735 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The behavior of narrow molecular weight distribution polymers has been investigated under uniaxial extension at constant deformation rate and at constant stress. It has been established that up to rupture these polymers behave as linear viscoelastic bodies. A detailed investigation of the rupture phenomenon has shown that the rupture of fluid polymers is due to their transition to the rubbery state at critical deformation rates, with the result that they disintegrate like quasi-cured rubbers. The effect of the temperature and the molecular weight on the critical conditions of rupture has been described in terms of viscoelastic relaxation.
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  • 162
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1747-1759 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The P-V-T relation and the heat capacity of a chlorinated polyethylene vulcanizate were measured. Several tests on the validity of thermodynamic treatments of the α relaxation process and the glass-transition temperature were performed by using dielectric properties. From a study using excess variables, it was shown that the entropy theories represented by the equations of Goldstein and Adam-Gibbs' were slightly better than the free volume theory represented by Doolittle's equation. However the study provided no distinction between the two entropy theories. Some tests were also performed on the pressure dependence of the glass-transition temperature, dTg/dP, and on H*V/H*V where H*V is the isochoric activation enthalpy and H*P is the isobaric activation enthalpy. Here, too, the entropy theories were better than the free volume theory. Goldstein's expression gave values of both dTg/dP and H*V/H*P closest to those from the dielectric experiments. The Adam-Gibbs' equation gave a temperature dependence for dTg/dP and H*V/H*P most similar to those from the experiments.
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  • 163
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1819-1829 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This is the first paper in a series dealing with the crystallization of high polymers at elevated pressures. Through an extension of the thin-film technique using osmium tetroxide staining, the measurement of lamellar growth kinetics at high pressures as well as the observation of micromorphological changes has proved possible. Three different morphological species of cis-polyisoprene have been detected in the pressure-temperature plane. A review is given of the conditions governing their formation and the growth kinetics of lamellar crystals are discussed in detail. Secondary nucleation theory is obeyed, the major effect of pressure being to alter the kinetics through the thermodynamic transitions. Variations in lamellar thickness with pressure may be explained simply in terms of the elevation by pressure of the equilibrium melting point.
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  • 164
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1855-1857 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 165
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1881-1891 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A terpolymer of butadiene-styrene-vinylpyridine has been crosslinked by addition of iron chloride. Differential enthalpic analysis gives evidence of a two-phase system. Electron microscope studies at 0.1 and 1 MeV show the existence of precipitates. The majority of these ironrich aggregates have diameters less than 100 Å. Their form is polyhedral but very nearly spherical. No crystallinity has been detected inside the clusters. Thus the existence of strong interactions as in crystals of FeCl3 hydrates is excluded.
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  • 166
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1945-1957 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It has been presumed in studies of the orientation of low-density polyethylene and its time dependence that the degree of crystallinity remained constant with elongation and did not vary with time following elongation. This paper represents a test of this hypothesis by several methods. The change in crystallinity accompanying stretching has been followed by a modification of an x-ray method for uniaxial orientation proposed by Ruland in which diffraction peaks are resolved into crystalline and amorphous components and their respective areas are determined by two-dimensional integration over both the Bragg angle and the azimuthal angle of diffraction. The weight-fraction crystallinity is then determined from the ratio of the weighted crystalline area to the total area. There appears to be no significant variation in crystallinity up to 50% sample elongation for both slowly and rapidly stretched samples at room temperature. The dynamic crystallinity change accompanying small amplitude vibration has also been determined by the dynamic x-ray diffraction technique and found to be negligible over a wide range of frequency. The degree of crystallinity has also been evaluated from the absolute infrared absorbance of crystallinity-sensitive bands and has also been found to be independent of elongation at room temperature up to 80% elongation. Changes have also been observed by this method during relaxation at constant length following rapid extension and have also been found to be negligible. These results also indicate negligible changes in rotational isomer population. Consequently, we conclude that changes observed during relaxation and vibration arise from orientational changes rather than changes in the degree of crystallinity.
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  • 167
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2103-2115 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A theory pertinent to the nucleation of polymer-diluent systems for molecules of finite molecular weight has been developed. These results have been applied to the crystallization from polyethylene-α-chloronaphthalene mixtures using molecular weight fractions of polyethylene ranging from 4,000 to 250,000. This analysis is carried out over the composition range extending from pure polymer to a polymer fraction of 0.30. According to this theory, the interfacial basal free energy decreases as either the molecular weight or diluent concentration decreases.
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  • 168
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2155-2171 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of diluent on molecular motions and glass transition in the polystyrene-toluene system was studied by means of dielectric, thermal, and NMR measurements. Three dielectric relaxations were observed between 80 and 400°K. On the basis of NMR measurements on solutions in toluene and in deuterated toluene, relaxation processes were assigned to segmental motions of polystyrene, rotations of toluene, and the local motions of polystyrene and toluene in order of appearance from the high-temperature side. The concentration dependence of the relaxation strength and of the activation energy for the primary relaxation (that at the highest temperature) show a step increment at about 50% by weight. The activation plots for the primary process were expressed by the Vogel-Tamman equation. With this equation, the temperatures at which the mean dielectric relaxation time becomes 100 sec is determined. This agrees well with the glass-transition temperature Tg and hence Tg in concentrated solution is expressed by \documentclass{article}\pagestyle{empty}\begin{document}$$ T_g \approx \frac{{ {B} }} {{ {A + 3} }} + T_0 $$\end{document} in terms of the parameters A, B, and T0 of the Vogel-Tamman equation. The values of A and B are, respectively, about 12 and 0.65 and independent of the concentration. The physical meaning of these parameters is discussed.
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  • 169
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2247-2250 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 170
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2259-2274 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Previous studies on the fold surface of polyethylene single crystals by means of selective degradation with ozone, together with associated GPC analysis, have been taken further. This refined method led to improved accuracy and reproducibility which enabled new and more quantitative information to be obtained than was possible earlier, and this in turn has led to new conclusions as regards the nature of the fold surface. The postulated picture of the existence of a distribution of fold lengths has received further support together with much additional information about the nature of the distribution itself. Also, differences in this respect between different crystal types have become apparent. The salient feature of the newly mapped distribution is that the majority of the folds terminate within closely defined limits with one minority fraction protruding beyond this level while another is buried within the crystal interior. The protruding folds become progressively looser and can be visualized as collapsed chains on the top surface while the folds which are buried more deeply become gradually sharper when progressing towards the crystal interior. The data on which these conclusions are based can be expressed in quantitative terms by which it could be assessed that there are differences between crystals formed at 90°C and 70°C the latter having a larger proportion of loose folds along the top surface of the crystal. A reasonable agreement between results of GPC and low-angle x-ray analysis gives support to these conclusions.
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  • 171
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2313-2320 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the effect of drawing on the glass transition temperature Tg of amorphous polycarbonate was carried out. The Tg attains a maximum at a draw ratio in the range from 1.6 to 2.0. The relationship between the change of structure and Tg is discussed in terms of the configurational entropy and the rate of molecular motion in local mode relaxation. The variation of Tg with drawing may be explained by using the iso-entropy theory. The frequency of the maximum in the dielectric loss fmax and the dielectric relaxation strength Δε of the β mechanism changed with drawing in the same way as that of Tg. Based on the parallel behavior in these results, it is reasonable to consider that the β process of local mode relaxation of polyesters such as PC and PET reflects the structure of the glassy state.
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  • 172
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2345-2355 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The energetics of kinks in polyethylene have been investigated by means of conformational energy calculations on crystalline arrays of C14H30, C18H38, and C22H46. All of the parameters required for assessment of relaxation effects by site theory were calculated including the static defect energies, barriers to defect reorientation, and site strains. Up to two deformable coordination shells in the surrounding lattice were included. In the energy minimization calculations, all molecular internal degrees of freedom were allowed to participate. The effects of chain mismatch along the C axis at large distances from the defect were calculated from a continuum theory. The static defect energy is calculated to be 6.6 kcal/mole for C14H30, and the barrier for reorientation of right-handed to left-handed kinks is 10 kcal/mole. The barrier to “unkinking” to the nondefect state is 2 kcal/mole. The strain induced by the defect is largely a shear in the {0 0 1} plane in the 〈1 1 0〉 direction. It is concluded that although the barrier to reorientation is consistent with kink reorientation contributing to the γ process the predicted intensity rules out any but a very weak contribution to the total process.
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  • 173
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2253-2257 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 174
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 165-171 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The preparation of chloroprene-methyl methacrylate copolymers in the presence of Lewis acids (Et1.5AlCl1.5) in hydrocarbon solvent and the effect of Lewis acids concentration on copolymer composition are described. 13C NMR spectra were obtained on these copolymers. In samples of high MMA content, tactic placements of MMA were observed as well as several different kinds of sequences for chloroprene and MMA. In samples of low MMA content, no tactic placements of MMA were found but several different kinds of chloroprene sequences were observed. From the analysis of the 13C NMR spectra of the different copolymers examined, it is apparent that all the various kinds of chloroprene sequences in these copolymers can be determined.
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  • 175
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 187-210 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been made of the crosslinking of linear polyethylene in solution. Networks containing a low number of trapped entanglements and elastically ineffective chain ends were prepared by crosslinking high molecular weight linear polyethylene in 1,2,4-trichlorobenzene solutions with dicumyl peroxide at 120°C. No syneresis was observed during crosslinking except at high peroxide concentrations. The networks were characterized by swelling measurements, infrared spectroscopy, and differential scanning calorimetry. The crosslinking efficiency, calculated from swelling, was found to be proportional to the square of the polymer volume fraction. The proportionality constant was 0.8, indicating close to unit efficiency for undiluted polymer.Chemical modification of the polyethylene chains by attachment of peroxide and solvent fragments was of the order of one foreign unit per elastically active network chain, depending on peroxide and polymer concentration. Sol-gel analysis indicated that no chain scission occurred. These results are shown to be consistent with a “cage” mechanism for crosslinking. The possible topological consequence of this mechanism, preferential crosslinking of entanglements, is discussed. The concentration of trapped entanglements was also found to be proportional to the square of the polymer volume fraction. The proportionality constant corresponds to a molecular weight between entanglements of 4000 for the undiluted polymer, which is close to the value of 4200 found for networks prepared from the undiluted polymer. Since the results obtained are based mainly on the use of the swelling equation, different aspects of the applicability of this equation for the evaluation of the crosslinking process are discussed. As regards the reference dimensions, which should be known for a quantitative application of the elastic theory, the results strongly support the use of the dimensions of the network chains after completion of crosslinking.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 251-262 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isolated spherulites of poly(methyl D-glutamate) (PMDG) were nucleated in bromoform. The morphology of these spherulites was investigated by SEM and photographic small-angle light scattering (SALS). From the SALS patterns, the development and growth of the spherulites could be noted. Films of PMDG cast from bromoform solution were found to be partially spherulitic. The mechanical properties of these films, prepared by different procedures, were compared with the general behavior of PMDG films cast from chloroform, the latter of which does not contain spherulitic texture.
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  • 177
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 299-308 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Data are presented to show that two correlations of viscosity-concentration data are useful representations for data over wide ranges of molecular weight and up to at least moderately high concentrations for both good and fair solvents. Low molecular weight polymer solutions (below the critical entanglement molecular weight Mc) generally have higher viscosities than predicted by the correlations.One correlation is ηsp/c[η] versus k′[η], where ηsp is specific viscosity, c is polymer concentration, [η] is intrinsic viscosity, and k′ is the Huggins constant. A standard curve for good solvent systems has been defined up to k′[η]c ≍ 3. It can also be used for fair solvents up to k′[η]c ≍ 1.25· low estimates are obtained at higher values.A simpler and more useful correlation is ηR versus c[η], where ηR is relative viscosity. Fair solvent viscosities can be predicted from the good solvent curve up to c[η] ≍ 3, above which estimates are low. Poor solvent data can also be correlated as ηR versus c[η] for molecular weights below 1 to 2 × 105.
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  • 178
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 317-322 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray line broadening measurements were used to determine the apparent “mosaic block” sizes of randomly oriented polyethylene and polyoxymethylene single crystals. Both dried-down and uncollapsed crystals were examined. PE lamellae were grown at 80, 85, and 90°C by isothermal crystallization from a 0.1% solution in xylene. POM crystals were grown at 125°C by self seeding from an 0.05% solution of the polymer in o-dichlorobenzene. A given preparation was split into two parts. One part was dried down in the usual manner, the other was exchanged to paraffin oil and the crystals never permitted to dry down. Previously reported studies used dried-down crystals and gave crystallite sizes of approximately 300 Å. More recently, using electron microscopy, it has been postulated that PE single crystals are free of “mosaic block” over regions of several thousand angstroms. It is evident from this present study that crystallite sizes in uncollapsed lamellae are significantly larger than those observed for the same crystals dried down. In the case of uncollapsed lamellae, one can explain the observed crystallite sizes solely on the basis of chain obliquity rather than by invoking the “mosaic block” model. It has also been determined that there is an upper limit to the crystallite sizes that can be observed in PE and POM crystals using wide-angle x-ray techniques. This limit may account for discrepancies between x-ray and electron diffraction.
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  • 179
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 323-342 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The morphology and thermal behavior of trans-1,4-polybutadiene single crystals prepared from dilute solutions in n-heptane have been investigated by electron microscopy, wide-angle and low-angle x-ray diffraction, and differential scanning calorimetry. The thickness of the single crystals of trans-1,4-PBD is much greater, for the same undercooling, than that of other linear polymers. From the calorimetric study, convincing evidence of the presence, in the single crystals, of crystalline blocks of form 1 with two different thermodynamic stabilities is obtained and the relative amounts are calculated. From thermodynamic considerations we find a value of 75°C for the equilibrium transition temperature between forms 1 and 2, 139°C for the equilibrium melting temperature of form 2, and 31.2 erg/cm2 for the fold-surface free energy of modification 2.
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  • 180
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 343-352 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Complete and partial alcoholyses of ethylene-vinyl acetate (E-VA) copolymers yield ethylene-vinyl alcohol (E-VOH) copolymers and ethylene-vinyl acetate-vinyl alcohol (E-VA-VOH) terpolymers, respectively. From the 220-MHz proton NMR spectra of E-VOH copolymers the stereoregular and chemical sequence distributions of the comonomers can be readily determined. Partially hydrolyzed E-VA polymers were acetylated with perdeuterated acetic anhydride. The monomer distributions in the terpolymers were then quantitatively determined by examining the proton spectra of the derived products. It was found that alcoholysis of E-VA polymers occurs preferentially at VA units which have neighboring VA groups.
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  • 181
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 353-365 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The small-angle x-ray scattering (SAXS) from quenched and annealed rigid polyvinyl chloride (PVC) has been measured using a Bonse-Hart system. After correcting for absorption, background, and beam divergence, the scattering has been placed on an absolute basis using a standard silica suspension as a reference. The scattering from annealed (6 days at 75°C) and unannealed PVC was identical within experimental error, varying with scattering angle in a manner similar to the SAXS from other amorphous polymers. The intensity decreases rapidly with increasing scattering angle over the ranges from 20 sec to 20 min. Beyond 20 min the intensity is fairly constant, decreasing only slightly with increasing angle. At the largest angles of measurement (in the range of 120 min), the measured intensity is close to the value calculated for thermal density fluctuations frozen-in at the glass transition.The angular variation of intensity is well described by the scattering from heterogeneities of various sizes and concentrations superimposed on the scattering from thermal density fluctuations. These heterogeneities range in radius from 50 to 4500 Å and, assuming the crystalline excess density, the total concentration of heterogeneities is less than 0.5%. The mean-square fluctuation in density, determined from the measured intensity invariant, is also consistent with such a distribution of heterogeneities.The present SAXS results on rigid PVC are inconsistent with the presence of nodular features as representative of the bulk polymer. Rather, it is suggested that they are associated with surface effects. It is further suggested that previously indicated volume fractions of crystallinity in rigid PVC (generally in the range of 5-12%) are incorrect, and that the model of a three-dimensional network of crystallites used to explain the rheological behavior of this material should be re-examined.
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  • 182
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 427-435 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal structure of poly(m-phenyulene isophthalamide) was determined by x-ray analysis. The triclinic cell, with a = 5.27 Å, b = 5.25 Å, c (fiber axis) = 11.3 Å, α = 111.5°, β = 111.4° and γ = 88.0° and space group P1, contains one monomeric unit. The crystal density is 1.47 g/cc. The molecules in the crystal are contracted by 1 Å per monomeric unit from the fully extended conformation, and the planes of the benzene rings and adjacent amide groups make angles of about 30°. The crystal is composed of molecular chains connected by N—H···O hydrogen bonds along the a and b axes forming a “jungle gym” network structure. The low tensile modulus of this polymer as compared with that of poly(p-phenylene terephthalamide) is attributed to the contracted molecular conformation.
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  • 183
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 521-529 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Raman spectroscopy has been used to analyze the characteristics of the crystal-crystal phase transition of trans-1,4-polybutadiene. The low- and high-temperature structures were found to coexist at the transition. The Raman spectra obtained at high temperature can be understood on the basis of the change in chain conformation associated with the phase transition.
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  • 184
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    Notes: Relaxation of stress and birefringence in simple extension has been studied for two samples of 1,2-polybutadiene with 95% and 88% vinyl content and weight-average molecular weight 1.9 and 2.9 × 105, respectively. The extension ratio, λ, ranged from 1.14 to 2.08, temperatures from 0 to 15°C, and times, reduced to 0°C, up to 3 × 105 sec. The stress-optical coefficient C was negative and positive, respectively, for the two samples, the difference being attributable to opposite signs and very different magnitudes of the contributions of the 1,2 and 1,4 moieties to the birefringence. For each polymer, C was independent of time but increased (algebraically) with temperature. For one polymer a very minor dependence of C on λ was observed. At any instant of time, the dependence of both stress and birefringence on λ could be described by equations of the Mooney-Rivlin form with coefficients C1,C2 and B1,B2, respectively. At short times the contributions of the C1 and C2 terms to the stress and of the B1 and B2 terms to the birefringence are roughly equal. With increasing time, C1 and B1 decrease gradually while C2 and B2 remain constant over several decades in time. Finally, C2 and B2 decrease rather rapidly. A tentative interpretation of these phenomena in terms of motions of entanglements is given.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 759-768 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experimental data on styrene-acrylonitrile (St-AN), and styrene-methyl methacrylate (St-MMA) copolymers reported in Part I of this series are tested by “two-parameter” theoretical relations. The Fox-Flory (F-F) parameter K is estimated using the F-F, Stockmayer-Fixman (S-F), and Inagaki-Ptitsyn (I-P) equations. In general, the K values obtained by the F-F equation are low for the three St-AN copolymer samples in the systems studied while the values obtained from S-F and I-P equations agree within the limits of experimental error. Values of K obtained from Kurata-Stockmayer (K-S) equation for sample SA1 agree with values obtained by the S-F and I-P equations. The specific solvent effect on the K values is discussed. Values of the unperturbed dimension r̄02/M̄w, calculated from the K values estimated from the S-F equation and from the homopolymer data are compared. Except in one case, the calculated r̄02/M̄w values from homopolymer data are low in comparison with the values obtained from experimental data, which shows that the presence of the repulsive interactions between unlike monomer units brings about an expansion of copolymer molecule. The effect of composition on the steric factor σ values is discussed. The long-range interaction parameter B, the excess interaction parameters ΔBAB, and χAB are calculated. The effects of composition and solvent on these parameters are discussed.
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  • 186
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 821-831 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The possible explanations for the temperature-induced reversible changes in long spacing in polymers are reviewed. The observation of particularly large changes in certain irradiated samples of oriented low-density polyethylene is reported. By combining these results with those obtained by DSC and other means it is concluded that the spacing changes are caused by partial melting of small lamellae within the lamellar stacks which alters the mean periodicity. The requirement of an irregular lattice explains why the effect is observed primarily in bulk samples and especially in materials which contain intrinsic irregularities.
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  • 187
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 861-867 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A technique is described which enabled exceptionally thin sections of rubbery material to be cut for electron microscopy, and applied to samples of polystyrene-polybutadiene-polystyrene (SBS) copolymers which contain the segregated S phase in the form of cylinders arranged in a regular hexagonal macrolattice throughout the macroscopic specimen, with center to center distance of 300 Å. The technique consisted of sectioning the material hardened by a combination of osmic acid treatment and cooling with liquid air. By this method longitudinal sections containing single layer S rods could be obtained as verified by appropriate tilting tests. Such sections enabled the viewing of single cylinders without overlap which in turn enables the study of the structure of individual cylinders and the effect of various treatments on this structure. Examples quoted include the yielding or breaking of individual cylinders on longitudinal deformation of the macroscopic sample relating to our mechanical studies to be reported elsewhere. The technique also enabled sectioning in the swollen state of samples which are not sectionable other wise and this leads to the recognition of new structures and results in an overall improvement of image quality even when the thinness itself is not the prime requirement.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 879-895 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Metal-insulator-semiconductor (MIS) techniques were used to show that 86-210 nm thick plasma-polymerized tetrafluoroethylene films on silicon stored only negative charge (electron acceptors). This property persisted at a reduced level when a 7 nm thick inner layer of hydrolyzed γ-aminopropyltriethoxysilane was combined with an outer layer of plasma-polymerized tetrafluoroethylene. The dispersion force contribution to the surface energy, γds, for the fluorocarbon films was found to be 6 mJ/m2 (erg/cm2) which is comparable with the lowest values found in the literature. X-ray photoelectron spectroscopy (XPS) revealed a substantial content of —CF3 groups in the fluorocarbon films. This finding coupled with the reported effects of noncrystallinity, crosslinking, and branching on the surface energies of fluorocarbon systems were used to explain the low surface energy and electrophilicity of the plasma-deposited poly(tetrafluoroethylene)s.
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  • 189
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 913-920 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple treatment based on continuum mechanics shows that weak interlamellar forces in crystalline n-alkanes should result in a characteristic upward shift of the frequencies of the longitudinal acoustical (LA) modes, which is independent of the chain length and decreases inversely with the mode order. A raman spectroscopic determination of the LA mode frequencies of a series of different n-alkanes confirms the theoretical conclusion and permits a derivation of a force constant characteristic of the interlamellar forces. The discussion results in a new formula valid for the LA mode frequencies of the orthorhombic n-alkanes in the acoustical limit and yields a new determination of the limiting elastic modulus Ec of crystalline polyethylene. The value obtained, Ec = 2.9 × 1012 dyne/cm2, is markedly smaller than the value derived by Schaufele and Shimanouchi neglecting the influence of the interlamellar forces on the LA mode frequencies.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 959-961 
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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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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1097-1109 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spectra of polarized light scattered from model networks of polystyrene swollen by benzene have been measured by optical mixing spectroscopy. Various series of networks of different functionalities and different lengths of the elastic chain elements have been investigated. A theoretical expression for the characteristic time constant of fluctuations has been derived from rubber elasticity theory. An analysis of the experimental results within the framework of this theory allows determination of the frictional constants of the gels.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1451-1459 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface tension γ of four copolymer latices, of their respective serums, and of aqueous solutions of dispersant alone were measured at various dilutions. By extrapolating the surface excess of dispersant (calculated by the Gibbs adsorption equation) both at the aqueous solution surface and at the serum surfaces to 1/c = 0 (c being the bulk concentration of dispersant) the same limiting site area Alim per adsorbed molecule was determined. Amounts of dispersant adsorbed by copolymer particles at various dilutions were determined from differences between the known total concentrations of the dispersant in latex and in serum at the same γ. These values were then extrapolated to the maximum adsorption at 1/c = 0 in latex. The surface area of copolymer particles was determined therefrom by using Alim. The average particle radius calculated this way agrees reasonably well with electron microscope measurements. Thus it appears that the method for determining latex particle surface area by surfactant titration may be calibrated by means of the Gibbs adsorption equation, provided one uses Alim and not the site area at the critical micelle concentration of dispersant.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1629-1639 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Intrinsic viscosities have been measured at 25° on five ethylene-propylene copolymer samples ranging in composition from 33 to 75 mole-% ethylene. The solvents used were n-C8 and n-C16 linear alkanes and two branched alkanes, 2,2,4-trimethylpentane and 2,2,4,4,6,8,8-heptamethylnonane (br-C16). This choice was based on the supposition that the branched solvent would prefer the propylene segments and the linear solvent the ethylene segments, due to similarity in shape and possibly in orientational order. It was found that [η]n - [η]br ≡ Δ[η] is indeed negative for propylene-rich copolymers, zero for a 56% ethylene copolymer, and positive for ethylene-rich copolymers. The Stockmayer-Fixman relation was used to obtain from Δ[η] a molecular-weight independent function of composition. The quantities (Δ[η]/[η])(1 + aM-1/2) and Δ[η]/M are linear with the mole percent ethylene in the range investigated with 200 ≤ a ≤ 2000. The possibility of using these results for composition determination in ethylene-propylene copolymers is discussed. Intrinsic viscosities in the same solvents are reported for two samples of a terpolymer with ethylidene norbornene.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1717-1720 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 195
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    Notes: The development of the shear stress at the start of shear flow at constant rate of shear κ was measured for polystyrene solutions in diethyl phthalate with a cone-and-plate rheometer. Ranges of molecular weight M and concentration c were 3.10 × 106-7.62 × 106 and 0.112-0.329 g/cm3, respectively. The shear stress as a function of time t exhibited a marked maximum at large κ when either M or c was relatively low. When M and c were high, the maximum was broad and low. In a few extreme cases no maximum was observed in the range of κ studied. The constitutive model of Bernstein, Kearsley, and Zapas could describe approximately the shear stresses at a sudden start and on cessation of steady shear flow with a memory function evaluated from the strain-dependent relaxation modulus. The strain dependence of the memory function for solutions of low M or c was approximately expressed as exp{-α|s|} where α is a constant (ca. 0.37) and |s| is the absolute value of shear strain. When M and c were high, the strain dependence was found to be more diffuse and to require several terms if approximated by exponential functions of |s|. The Lodge model based on a strain-rate dependent relaxation spectrum was not able to describe the strain-dependent relaxation modulus as well as the interrelation between shear stresses at a sudden start and a cessation of steady shear flow.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1729-1730 
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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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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1755-1767 
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Low dielectric loss polyethylenes have been produced by γ-radiation polymerization of oxygen-free ethylene monomers. Dielectric measurements were made at 500 MHz and 20°C. The lowest dielectric loss tangent of the polyethylene was 3.3 × 10-5. Polar groups contributing to the dielectric loss have been found to be carbonyl groups, terminal vinyl groups, methyl groups, and hydroxyl groups contained in the polyethylene. The contribution of each group to the loss tangent has been calculated from a comparison of the variation of the loss tangent with the content of each group as determined by infrared analysis. It has been found that the reduction of the loss tangent is mainly due to the decrease in the concentrations of the carbonyl groups and the terminal vinyl groups and that the presence of a considerable amount of the hydroxyl groups prevents a further reduction of the loss in the polyethylenes. The results obtained from the analysis of the radiation-polymerized polyethylenes were applied to commercially available polyethylenes.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1789-1800 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: From the temperature dependence of integrated intensities and from line widths in high-resolution 1H-NMR spectra, the relaxation times T1 and T2 of protons in CH2 and CH3 groups of polyisobutylene in CCl4 solution have been determined. Although the relaxation time T1 of methylene protons is determined mainly by intragroup interactions, intergroup interactions of two methyl groups from each two consecutive monomer units were found to contribute considerably to T1 of methyl protons. The Structure and mobility of polyisobutylene (PIB) molecules in solution is discussed on the basis of the relaxation time data.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1839-1854 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Highly porous interpolymer ion-exchange membranes have been prepared from poly(styrene sulfonic acid), PSSA and poly(vinylidene fluoride) PVdF using a casting solvent of dimethylformamide and hexamethylphosphoramide. The membranes have been characterized by their water content, concentration potential, ionic conductivity, and their hydraulic permeability. An estimation of the porosity of the membranes has been made from the relative conductance of the potassium and the tetrabutylammonium ions in the film. This porosity has been compared with that derived from a consideration of the water flux through a Poiseuille-type pore.
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    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1725-1727 
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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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