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  • LUNAR AND PLANETARY EXPLORATION  (1.440)
  • Physics  (957)
  • 1995-1999
  • 1980-1984
  • 1975-1979  (2.397)
  • 1977  (1.210)
  • 1975  (1.187)
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Verlag/Herausgeber
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  • 1995-1999
  • 1980-1984
  • 1975-1979  (2.397)
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  • 1
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 127-135 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Fracture surfaces of an oriented polystyrene (by stretching 150% at 280°F) show many of the same features observed in the fracture of ordinary polystyrene: craze formation followed by quasi-viscous separation of the craze layer or by quasi-brittle fracture along the craze boundary. In cleavage fracture along the direction of orientation, advance fractures are initiated in flat areas covered, if at all, by an extremely thin layer of craze: the initiation of the “crazeles” fractures appears to arise from the orientation of the molecules rather than the presence of impurity particles.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 43-57 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: We describe a new technique for producing fibrous crystals from shear-induced crystallization of polymer solutions and polymer melts. Our technique makes use of a modified version of the 4-Roller apparatus originally developed by G. I. Taylor to study the formation of emulsions. This apparatus generates a planar extensional flow field in which macromolecules are extended more easily than in flow fields with transverse velocity gradients.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 73-86 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Extrudates of solid linear polyethylene prepared under proper pressure and temperature conditions have a high c axis orientation along the extrusion direction, with lamellar crystals and amorphous layers stacked alternately along the extrusion direction. Kink bands were formed by compressing the oriented extrudate at room temperature along the extrusion direction. Inspection of the kink bands by wide-angle and small-angle x-ray diffraction and electron microscopy revealed that the fiber axis was rotated from the original axis direction by 70-75° and that the lamellar crystals were inclined to the fiber axis in the kink band by 55-60° and stacked nearly parallel to the kink boundary. The superstructural change during the formation of the kink band could not be interpreted in terms of uniform c axis shear alone. In addition to such a mechanism, it was necessary to take into account intermicrofibril and/or intercrystallite slip.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 137-149 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The complex compliance in extension of gels of poly(vinyl chloride) (PVC) in di(2-ethylhexyl) phthalate (DOP) and in tricresyl phosphate (TCP) was measured over the frequency range from 0.6 to 0.006 cps and the temperature range from -66 to 65°C: the weight fractions of DOP and TCP in the gels were 0.32, 0.40, 0.49, and 0.59. Measurements were carried out in an apparatus using forced low-frequency longitudinal osillations. Data for the gels could not be combined by the method of reduced variables, since there were gradual changes with decreasing temperature, attributable to an increase in crystallinity. Application of the reduction method of Ninomiya and Ferry for solutions of crystalline polymers was found to be successful. The apparent melting temperatures (T′m) were obtained from the temperature dependence of the vertical shift factors. An apparent heat of fusion of ca. 120 cal/mole of monomer unit was found. This melting range was in agreement with that of secondary crystallinity in plasticized PVC reported in calorimetric studies by Juijn. With decreasing temperature, two phenomena occurred in the temperature range from Tg + ca. 80°C to Tg: the vitrification of a concentrated amorphous solution and the slight crystallization of the polymeric component. The larger the difference between Tg and T′m the broader the primary dispersion zone on the frequency scale. This broadening effect was explained as due to the difference in dependence of Tg and T′m on plasticizer concentration, without any need to consider any specific interaction between plasticizer and PVC.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 223-241 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Certain inorganic nitrate salts are quite soluble in the polymers studied, namely, cellulose acetate, poly(vinyl acetate), poly(vinyl alcohol), poly(methyl methacrylate), and poly(methyl acrylate). Large effects upon the glass-transition temperature were observed in those systems where the transition could be readily measured. Large shifts in the infrared spectra of both the inorganic nitrate salts and in the polymer carbonyl and ester ether frequencies have been observed. These observations have been interpreted in terms of complex formation between these polymers and salts in the solid state. The proposed structure of the complex explains the nature of the infrared shifts both for the nitrate salts and the polymers as well as explaining the concentration effects observed. Effects of the solvating environment upon the salt and polymer spectra remain unexplained. The large glass-transition effects are a result of the degree of solubility of the salts in the polymers and the interactions between them. However, the reason why, in some cases, the change in the transition temperature as a function of concentration goes through a maximum is unclear.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 263-274 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The deformational, swelling, and potentiometric behavior of poly(methacrylic acid) gels was measured as a function of the degree of crosslinking, ionic strength, and degree of ionization. The comparison of the stress-strain behavior with theoretical relations derived in the preceding part has shown that the relations are valid only if an increase is assumed in the number of monomeric units in the statistical chain segment with increasing degree of neutralization of the gel. This dependence is affected by the salt content in the swelling solution and is also dependent on the activity coefficient of counterions. The pK0 values for an undissociated gel approach pK0 = 5.0 and increase somewhat with degree of neutralization. The swelling equilibria are in qualitative agreement with theoretical assumptions; their quantitative agreement depends on the activity coefficient of counterions.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 333-338 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Samples of n-hexatriacontane irradiated in the crystalline and molten states were compared as regards the GPC chromatograms of the partially crosslinked products. From differences in the elution volumes it could be inferred that there is a greater trend for random linking along the chain in the sample irradiated in the melt as opposed to preference for end-type linking in the samples irradiated as crystals. In the course of this work the applicability of the GPC technique for detecting short (methyl) branches and for distinguishing between the position of these branches along the chain has also become apparent.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 8
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Partial molar excess free enthalpies (or excess chemical potentials) at infinite dilution were obtained over a large temperature range by gas chromatography. Data on n-alkenes in Apiezon M are interpreted by the Prigogine-Patterson theory; data on normal and branched alkanes in squalane and polydimethylsiloxane (PDMS) are discussed in terms of the Prigogine-Patterson theory and the solution theory of Flory, Orwoll, and Vrij. For the alkane-PDMS systems heats of dilution and partial excess heat capacity data are given.The aim of this work is to get some insight in the applicability of these solution theories to mixtures of fluids, the properties of which may slightly violate the basic assumptions of these theories. It is shown that orientational order in and a large cross-sectional chain diameter of the polymer solvent do not affect their applicability to the partical molar excess free enthalpies of apolar mixtures, whereas large dissimilarities between the force fields around the segments of the mixture components and/or dissimilar chain flexibilities detract from the applicability of these theories (alkanes in PDMS).Special attention has been paid to the effects of dissimilar size and shape of the segments of the mixture compounds on the magnitude of the interchange interaction parameter. It is shown that the multiple-connected segment model after Lichtenthaler et al. does not warrant a reliable combinatorial contribution. Comparison of the interaction parameters obtained for n-alkanes in n-alkanes, Apiezon, squalane, and polyisobutylene and for branched alkanes in squalane reveals that the magnitude of this parameter is affected by small end-effects due to the relative weakness of methyl-methylene interactions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 437-441 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 477-492 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The effect of base stacking interactions on the conformation of poly(9-vinyladenine) (PVAd) was investigated by osmometry, intrinsic viscosity, and light-scattering measurements. At neutral pH, ideal solution behavior (θ conditions) for this polymer was observed at 26 and 40°C. Intrinsic viscosity measurements revealed a conformational transition on heating from 26 to 40°C, while the ultraviolet absorbance of the solution was insensitive to the change. The transition was accompanied by an inversion in sign of the entropy parameter from negative to positive and an increase in the partial specific volume. At 40°, the variation of intrinsic viscosity with molecular weight corresponded to a random coil conformation, but the characteristic ratio, r̄02/nl2 = 8.6 ± 0.2 indicated that the unperturbed dimensions were smaller than usually observed for comparable vinyl polymers. At 26°, a rare macromolecular phenomenon was found, the intrinsic viscosity-molecular weight relation and the estimated r̄02/nl2 of 6.0-6.8 suggested that the PVAd was in a very highly compacted coil conformation, approaching a semirigid sphere. It is proposed that this effect be named the introversion phenomenon. Unlike polyadenylic acid, whose unperturbed dimensions increase with decreasing temperature due to nearest-neighbor base stacking, the results reported here suggest that both nearest-neighbor and long-range intramolecular base stacking occur in PVAd. The different stereochemical arrangements of bases in PVAd and Poly A are probably responsible for the opposite behavior observed.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 533-566 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The deformation of polyethylene in terms of structural processes has been investigated by low-and wide-angle x-ray diffraction in the case of low-density and, to a lesser extent, high-density polyethylene. The samples possessed a range of simple textures which enabled the deformation processes to be identified. The results are interpreted in terms of a model of stacks of lamellae which have axes along the original draw direction and which deform by lamellar slip, chain slip, and lamellar separation. In most cases these processes accounted for the macroscopic strain but in some cases discrepancies were observed which could be accounted for by inhomogeneous deformation or by the effects of a distribution of lamellar thicknesses. Attempts were made to identify fibrillar slip, without success. The relative contributions of the various deformation processes are examined as a function of temperature and sample treatment by defining a compliance constant for each process. Below room temperature, the results are consistent with expectations based on the α and β mechanical relaxations, whereas the unusual effects at high temperatures are attributed to gradual melting. The compliance constants are also found to depend on the annealing temperature of the sample, and are used to predict the mechanical anisotropy. The volume changes accompanying lamellar separation are examined. They were less than expected in low-density polyethylene, but satisfactory agreement was obtained in high-density polyethylene. A general relation is suggested between volume changes and the lateral development of the lamellae. Hence in narrow lamellae the interlamellar layer can contract laterally whereas the greater constraints imposed by wide lamellae lead to void formation. Other effects examined include the reversibility of the processes which is most marked in the case of chain slip and which is explained by the presence of restoring forces in the amorphous regions including the fold surface. Finally, the differences between low- and highdensity polyethylene are highlighted, emphasizing the part played in the deformation by the amorphous component.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 599-605 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 663-666 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 675-682 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In the preceding paper, general equations were established for the motions of chains confined to a tetrahedral lattice. In the present paper, bond orientation correlation and autocorrelation functions are explicitly calculated for the case where only three-bond elementary motions are considered. Effects due to the chain end are analyzed and the relaxation time distribution function is established. The expressions obtained reflect the influence of the chain structure. Finally, to characterize the dynamic behavior of chains in orientation relaxation experiments, the notion of an independent kinetic segment is proposed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1167-1176 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A study of the morphology of thermally induced crystallization in poly(N-vinylcarbazole) has shown the formation of folded chain lamellae. Diffraction analysis of multiple and single lamellae indicates a paracrystalline structure with hexagonal symmetry about the chain axis and an interchain spacing of 12.00 Å. No sharp reflections due to chain axis periodicity were observed and the chain axis period was calculated from the crystalline density extrapolated to 100% crystallinity. This gave a chain axis period/monomer unit of 2.16 Å consistent with an isotactic 3/1 screw axis and a basic trigonal structure with a = 12.00 Å and c = 6.47 Å.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1215-1231 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The viscoelastic properties of chain molecules varying in flexibility and length have been calculated by use of the bead-spring model theory of Zimm. In the evaluation of the hydrodynamic interaction parameter, the number of springs in the bead-spring model, N, has been selected from the range in which the properties predicted by the theory are insensitive to the value of N. The results for limiting viscosity number agree with those predicted by the Yamakawa-Fujii theory of the limiting viscosity number of wormlike chains. The theory also fits the experimental data of Johnson on a sample of polystyrene of molecular weight 860,000 in theta solvents at infinite dilution. The viscoelastic properties of some moderate molecular weight deoxyribonucleic acid solutions are predicted to deviate from the non-free-draining behavior toward the free-draining behavior.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1269-1274 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Earlier work showed that heating causes poly(diethylsiloxane) to undergo a first-order transition from a semicrystalline solid to a more mobile viscous - crystalline material. The latter is composed of two phases and analogies between polymer and liquid crystal morphology and behavior have been made. The viscous - crystalline phase in PDES appears to be unique since the literature is devoid of other documented examples. In this study, spin - lattice and spin - spin relaxation times were measured over a wide temperature range. They show a glass transition at 138°K, a crystal - crystal transition at 206°K, and a transition around 250°K which results from translational motion of the polymer chains with respect to each other. This motion is observed in the amorphous phase at a lower temperature than in the crystalline phase. Translational motion in the crystalline phase is observed on melting of the crystallites. The spin - spin data permitted monitoring of the molecular motions in each phase and the data suggest that these phases exert some influence on the molecular motions of each other. The viscous - crystalline phase in PDES may represent a unique model for studying and understanding “precrystalline” behavior and structure in amorphous solids.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1333-1346 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Real and imaginary parts of the dielectric constant of wet and dry polyglycine have been measured for several temperatures over a wide range of frequencies. A simple, rather crude model, proposed earlier for nylon 66, fits the experimental data rather well, but the blocking coefficient p is larger and adsorption effects are more important.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1377-1386 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Measurements of dielectric relaxation have been made for a series of solutions of poly(methyl methacrylate) in toluene. A range of concentrations between 2% and 20% was used for a number of polymers of differing molecular weights. The dispersion was studied over the frequency range 103-106 Hz for temperatures between -90°C and +20°C. It has been found that both the distribution of relaxation times and the activation energy increase with increasing concentration. The magnitudes of the effects vary with molecular weight. A significant observation is that the increase in dielectric constant with concentration is not linear.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1417-1446 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The melting behavior of restrained isotactic polypropylene fibers is examined quantitatively in terms of the influence the anisotropic structural state of the polymer has on the observed properties. Two endotherm peaks are observed to occur in some of the samples. The formation and location of the multiple peaks are determined by the orientation of the noncrystalline chains, and is independent of the fabrication path used to achieve that orientation. Above a certain minimum orientation of the noncrystalline chains, multiple endotherm peak formation occurs. The high-temperature endotherm (T2M) extrapolates to an ultimate melting point for fully oriented noncrystalline chains of 220°C, while the lower-temperature endotherm (T1M) extrapolates to an ultimate melting point of 185°C. Noncrystalline chain orientation influences the endotherm temperature through its changing configurational entropy. It is shown quantitatively that the noncrystalline polymer must be considered as plastically deformed, since rubber elasticity theory is not followed as predicted. The melting behavior of isothermally crystallized samples are also reported to further elucidate the nature of the observed endotherms.
    Zusätzliches Material: 25 Ill.
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  • 21
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Further stress relaxation experiments, mostly at 50°C, are reported on mixtures of crosslinkable ethylene-propylene terpolymer with saturated ethylene-propylene copolymer (molecular weights 3.6 and 45 × 104) containing up to 50% by weight of copolymer, crosslinked by sulfur to leave the saturated copolymer unattached and free to reptate in the copolymer network. Stress relaxation was measured in small simple elongations (stretch ratio about 1.15) on samples which had been extracted to remove a large part of the unattached copolymer and dried. The relative increase in modulus at long times (104 sec) increased with the proportion extracted; at short times (1 sec), extraction of the lower molecular weight copolymer increased the modulus to about the same extent but extraction of the higher molecular weight copolymer affected it very little. The relaxation modulus of the copolymer extracted from sample 50H (50% copolymer of high molecular weight), obtained by difference, agreed with that for the total copolymer except for a small difference probably attributable to molecular weight selectivity in the extraction. Stress relaxation was measured on sample 50H at six higher elongations up to a stretch ratio of 3. The dependence of stress on time and strain was consistent with an analysis based on the following assumptions: (a) linear additivity of the network and unattached copolymer contributions, (b) strain-time factorization of the stress contributions from the individual components, (c) a strain dependence for the unattached component corresponding to the presence of a Mooney-Rivlin C2 term only, (d) a strain dependence for the network component which does not follow the Mooney-Rivlin equation but is dominated by a simple neo-Hookean term.
    Zusätzliches Material: 5 Ill.
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  • 22
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1705-1719 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Chain characteristics of a linear sulfonate-containing homopolymer, sodium poly(3-methacryloyloxypropane-1-sulfonate), in aqueous salt solutions (ionic strength, Cs = 0.01N to 5N NaCl) have been investigated by light scattering and intrinsic viscosity. The molecular weight (M̄w)-viscosity relation can be well described by the Mark-Houwink and the Stockmayer-Fixman equations. The coil is highly expanded even in the most concentrated NaCl solution (6N), and no 1:1 electrolyte was found to precipitate this polymer.A linear relation was observed between the viscosity expansion factor, α3η, and (M̄w/Cs)1/2. Examination of the data in terms of theories for excluded volume and hydrodynamic interaction suggests that the coil experiences dominant hydrodynamic interaction, corresponding to a nondraining coil, and the second virial coefficient and coil expansion at high Cs can be correlated by the Flory-Krigbaum-Orofino equation. Results for this polymer are compared with those for other polyelectrolytes, and are discussed in terms of chain structure, flexibility, and hydrophobicity.
    Zusätzliches Material: 10 Ill.
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  • 23
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1783-1787 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: When a mixture of two monodisperse samples of poly-α-methylstyrene is thermally degraded, the components behave independently, as a first approximation, as shown by GPC and rate of volatilization data. The ratio Mw/Mn, before approaching the ultimate value of 2.0, first goes through a minimum at a much lower value.
    Zusätzliches Material: 3 Ill.
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  • 24
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1809-1817 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The overall rate of crystallization of isotactic polystyrene from dilute solutions, 1% by weight, in trans-decalin and benzyl alcohol was studied as a function of temperature using dilatometry. These solvents were chosen because the dissolution temperatures of crystalline isotactic polystyrene are practically the same in both solvents. The overall rate of crystallization as a function of crystallization temperature showed a maximum in both solvents at about 50°C. At lower crystallization temperatures the rate of crystallization is much lower. The overall rate of crystallization of isotactic polystyrene in benzyl alcohol is far larger than in trans-decalin at the same undercooling throughout the temperature range, which is in apparent contradiction to present crystallization theories. At very large undercooling (Tc lower than about 0°C) the solutions of isotactic polystyrene in both solvents quickly become “rigid” gels. Surface replicas of freeze-etched gels indicate that a fringed micelle type of crystallization takes place at these low temperatures. The transition from folded chain crystallization to fringed micelle crystallization may be due to a stiffening of the polymer chain below about 50°C, with a reduced rotational mobility of the phenyl groups on the chain. If very dilute solutions, below 0.5% by weight, are crystallized at these low temperatures no gels were formed but fibrous crystals are produced which could be observed under the polarizing microscope.
    Zusätzliches Material: 6 Ill.
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  • 25
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1849-1854 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1871-1879 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The mechanical properties (Young's modulus, ultimate tensile strength, deformation processes) of extended-chain polydiacetylene crystals are investigated. The properties observed are similar to those of metal and ceramic whiskers. The elastic modulus is strain-dependent and the ultimate tensile strength increases with decreasing crystal size. The maximum tensile strength observed was 1700 Nmm-2. The ultimate tensile strength seems to be controlled by the presence of a small number of defects near the surface at which fracture nucleates. Irreversible deformation of the crystals was observed to occur by crack propagation normal and parallel to the direction of the macromolecules. The observed mechanical behavior corresponds to exceptionally high per-chain properties. The per-chain modulus obtained for these crystals is nearly as high as that of diamond. A chain-aligned polyethylene fiber with the same per-chain mechanical properties would have an ultimate strength as high as 0.9 × 104 Nmm-2.
    Zusätzliches Material: 3 Ill.
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  • 27
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1913-1923 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Contraction experiments were performed on hot-stretched polystyrene during isothermal annealing and tempering. Activation energy spectra were obtained from the experimental data using the Primak theory. In the case of isothermal annealing the theory of Kimmel et al. with shift factors was used. There is an appreciable difference between this spectrum and that obtained from the tempering experiment by the original theory without shift factors. These two spectra should be the same according to the theory. In order to resolve the conflict, we have included a correlation between activation processes in the fundamental equation of the Primak theory. A new formula for calculating the activation energy spectra was obtained. For isothermal annealing, it can be written the same as that of Kimmel et al. The shift factor is also included in the formula for tempering. The activation energy spectra obtained by the new formula gives good agreement between the two methods.
    Zusätzliches Material: 6 Ill.
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  • 28
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1939-1944 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Observations by transmission electron microscopy suggest that surface-controlled recrystallization of polyethylene occurs by the solid state nucleation and growth of new crystals with (110) or (110) planes parallel to the free surface. The nucleation site of these crystals is the free surface. The growth process involves the migration of [002] tilt boundaries suggesting that these boundaries have high mobilities. The migration process may occur by the lateral rearrangement of the macromolecules in the [002] tilt boundary.
    Zusätzliches Material: 6 Ill.
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  • 29
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2129-2134 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The peel strength found in the trousers-type peeling process is treated for the case in which the adherends, assumed to be flexible but inextensible are bonded by rubbery viscoelastic adhesives.Taking into consideration energy dissipation during deformation of the adhesive, Griffith's criterion is extended to the peeling of viscoelastic materials. For the peeling force per unit width f it is deduced that 2f = Γ + u′h, where T is twice the surface energy, u' is the energy dissipation per unit volume of adhesive, and h is the thickness of the adhesive layer. Values of u' obtained from peeling tests for various thicknesses are compared with those from the tensile tests and found to agree with the above relation. The deduction that the peel strength is independent of the thickness for adhesives with no energy dissipation is also verified experimentally.
    Zusätzliches Material: 4 Ill.
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  • 30
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2289-2298 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The low-frequency (10-3 to 5 × 10-1 Hz) dynamic mechanical properties were obtained over the temperature range of 25 to 96°C for 1,5-trans-polypentenamer networks prepared in the presence of 0,0.01, 0.02, 0.04, 0.1, 0.2, and 0.4% dicumyl peroxide. For comparison, similar properties of 1,4-polybutadiene crosslinked with 0.02% dicumyl peroxide were also measured. Superimposed curves for the components of the dynamic compliance, Jp′ and Jp″, reduced to 25°C were obtained and the retardation spectra L were calculated over a range of four logarithmic decades deep in the rubberlike region. It was found that networks containing 0.04 and 0.1% DCP have a small loss maximum Jp″ in the reduced frequency region log ωaT between -2 and 0 which can be assigned to relaxations of untrapped entanglements. The values of (Jp′ - 1/ωη) for very lightly crosslinked polypentenamer networks approached equilibrium very slowly compared to 1,4-polybutadiene crosslinked to the same degree, which suggests the participation of very long retardation times of this polymer which is also probably reflected in the comparatively high values of C2 of the Mooney-Rivlin equation.
    Zusätzliches Material: 4 Ill.
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  • 31
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2331-2343 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The dynamic mechanical properties of a number of ultra-highly drawn polyethylenes have been studied over a wide range of temperature. It is shown that the materials possess low temperature Young's moduli as high as 1.6 Mbar, a figure which approaches the theoretical and experimental values for the c-axis crystalline modulus of this polymer.The α and γ relaxation processes are still clearly discernible even at highest drawn ratios (ca. 35) and a quantitative analysis of the results, using structural data obtained from broad line nuclear magnetic resonance (NMR) measurements, suggests that the data are consistent with a modified series model.
    Zusätzliches Material: 10 Ill.
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  • 32
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2385-2390 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In the initial stage of the development of transcrystallinity, nuclei appear sporadically on the substrate. The growth rate and melting temperature of the transcrystalline region are found to be the same as those of spherulites nucleated in the bulk of the polymer. Nucleation densities ns at the interface, and nb in bulk, for the crystallization of isotactic polypropylene, poly(ethylene oxide), and poly(butene-1) in contact with various substrates, have been measured by counting the number of spherulites generated. Despite variations in the results from various causes, the quantities ns and ns/nb are useful parameters for characterizing the nucleating ability of various substrates.
    Zusätzliches Material: 2 Ill.
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  • 33
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2391-2400 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In the melt crystallization of isotactic polypropylene, poly(ethylene oxide) and poly(butene-1) in contact with substrates, the existence of a fixed number of nucleating sites on the substrate surfaces has been established. When these sites become active successively (the transient in the number of nuclei is long) during crystallization, pseudohomogeneous nucleation on the substrate occurs. Nucleation rates for poly(butene-1) and poly(ethylene oxide) on substrates and in bulk have been measured. These data can be used for comparing the nucleating ability of substrates. Estimates of the variation of bulk nucleation rates from one volume element to another as well as for repeated crystallization within a given volume element have been included. Finally, the temperature coefficients of heterogeneous nucleation rates have been combined with the temperature coefficient of spherulitic growth rate of poly(butene-1), to yield values of the interfacial energy parameters appearing in the theory of heterogeneous nucleation. The quantitative characterization of the nucleating ability of substrates by this method is an improvement over the mere use of nucleation densities or nucleation rates.
    Zusätzliches Material: 4 Ill.
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  • 34
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1-9 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The autocorrelation function of orientations, derived for the model of conformational jumps in a chain described in a tetrahedral lattice, has been tentatively applied to dielectric relaxation data. The complex dielectric relaxation of polymers can be interpreted by the aid of only two relaxation processes. In the case of poly(p-chlorostyrene) in solution, the characteristic times that we have calculated agree favorably with the fluorescence-depolarization results. The model has been shown to be consistent with the empirical decay function exp[- (t/τ)β] proposed by Williams.
    Zusätzliches Material: 5 Ill.
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  • 35
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A study has been conducted on the solid-state extrusion of three semicrystalline polymers:poly-propylene (PP), poly(vinylidene fluoride) (PVDF), and high-density polyethylene (HDPE). HDPE has been extruded in continuous lengths with area reductions up to 25× at temperatures substantially below the melting region. Such extrusion has been identified as a solid-state process, since measurements of the temperature of the polymer during extrusion indicate the absence of significant heating due to deformation. In contrast, continuous lengths of PP and PVDF could not be obtained substantially below their melting temperatures, indicating that crystallization during extrusion is an important process for these polymers. Under severe extrusion conditions (low temperatures, high area reductions. etc.), all three polymers failed within the tapered region of the extrusion die. Two modes of failure have been identified, brittle fracture and, surprisingly, necking. Grid-line distortion patterns and a highly simplified upper-bound plasticity analysis both indicate that shear deformations are a major factor during high-stress extrusion.
    Zusätzliches Material: 5 Ill.
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  • 36
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 103-108 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Polystyrenes lightly substituted with either tertiary amine groups or nitrophenol groups have been allowed to interact in concentrated t-butylbenzene solution and in bulk polymer. Above the glass transition temperature a temperature dependent equilibrium is achieved in the bulk polymer between the two substituents and the amine salt of the phenol. The degree of association found is considerably greater in the bulk polymer than in solution. The results show that much interpenetration of the polymer occurs, and the results are discussed in terms of models of the bulk amorphous state of the polymer.
    Zusätzliches Material: 1 Ill.
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  • 37
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 109-125 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The Flory-Huggins formulation of the combinatorial entropy, supplemented with residual free energy, is applied locally to obtain the interfacial free energy and the concentration profile of polymer in the interface between two demixed polymer solution phases. Two choices were investigated for the residual free energy: a “regular solution” formulation and an empirical formulation of Koningsveld for polystyrene in cyclohexane. Asymptotic, analytical solutions of the equations near the critical solution point and solutions obtained by numerical calculations are given as a function of temperature for several molecular weights. At temperatures farther below the critical temperature the equations have no solutions. The reason for this is not entirely clear. The local formulation of the free energy used here is an improved version of a previous one, which gave wrong results for asymmetric systems (polymer in a low molecular weight solvent). This newer version is consistent with our theory of critical opalescence and gives a relation between the interface “thickness” and the correlation range of the concentration fluctuations. The calculated correlation ranges were in good accord with those found experimentally by Debye, Chu, and Woerman. That the newer version of our equations for an interface gives no acceptable solutions at lower temperatures could be caused by a “collapse” of a diffuse to a sharp interface as suggested by Nose.
    Zusätzliches Material: 7 Ill.
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  • 38
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 97-102 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Raman depolarization ratio measurements (ρ) have been made for 20% polydimethylsiloxane (PDMS) solutions in benzene and 10% Polystyrene (PS) solutions in cyclohexane over the temperature range 20 〉 T 〉 200°C. The bands studied were the 2907 cm-1 methyl stretch in PDMS and the 1002 cm-1 ring breathing mode in PS. The measured ρ are related to rotational isomeric state populations and a qualitative picture of the polymer conformation changes over much of their miscible ranges is described. Measurements of ρ for PDMS gum over the temperature ranges 20 〈 T 〈 200°C have been obtained and the upper theta temperature has been determined to be 171 ± 3°C for PDMS/benzene. Quantitative information about the variation of the polymer solvent interaction parameter χ can in principle be obtained.
    Zusätzliches Material: 2 Ill.
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  • 39
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 137-144 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Preferential solvation and intrinsic viscosity measurements are reported for three systems: polystyrene + benzene + methanol, polystyrene + carbon tetrachloride + methanol, and poly(2-vinylpyridine) + ethanol + cyclohexane. Plots of the coefficient of preferential solvation λ′ as a function of variation of the segment density Δρ for a given ternary system, give a single curve for a large range of molecular weight and solvent mixture composition. This correlation between λ′ and Δρ is verified in previously published data.
    Zusätzliches Material: 9 Ill.
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  • 40
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 303-321 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: An extensive study has been carried out on the effect of ionizing radiation on polyethylene in the form of solution-grown single crystals to follow up preceding investigations which had indicated that the radiation-induced effects along the fold surfaces could be significantly different from those within the crystal interior. In this first part of the series, radiation-induced crosslinking was investigated in the case of “crystal core” material. This material, obtained by removal of the fold surface by oxidative degradation with ozone, consists of isolated foldfree crystal layers of dicarboxylic acids of uniform length, the length itself depending on the fold length of the starting crystal. This “core material” was irradiated by γ rays and the effect of crosslinking was followed by GPC analysis by recording the development of dimer, trimer, etc., peaks in the chromatograms. For a given dose, the fractional amount of crosslinked material is independent of the chain length. This, together with other effects described, provides unambiguous evidence that crosslinking occurs at the chain ends or, in other words, that there is no crosslinking within the interior of the paraffinoid lattice. Further, no permanent scission was observed to occur within the lattice, at least in amounts detectable by the present molecular weight measurements. The obvious significance of these effects for radiation studies on paraffinoid substances in general, beyond those of the present long-chain dicarboxylic acids, is discussed prior to utilizing them in the study of chain-folded polyethylene crystals in the following parts of the series.
    Zusätzliches Material: 7 Ill.
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  • 41
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 351-359 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Freeze-dried chain folded single crystals and the single crystals without amorphous surface layers (crystalline cores) of different thicknesses of linear polyethylene were irradiated with 60Co γ-rays up to 600 Mrad. Concentration of trans-vinylene double bonds and conjugated diene produced during irradiation of the crystals was measured by infrared. Concentrations of trans-vinylene and of the conjugated diene were independent of thickness of crystalline core which suggest that the double bonds wer randomly distributed in the crystalline parts of the crystals. Concentrations of trans-vinylene and of conjugated double bonds were lower in chain-folded crystals than in the crystalline cores and this suggests that the folds (amorphous surface layers) are less preferential sites for formation of the double bonds. The zero-order growth and first-order decay kinetics of trans-vinylene double bonds was studied by the equation derived by Dole et al1. The equation is strictly obeyed up to 300 Mrad and the results then deviate. Since there is the decay of trans-vinylene double bonds and though there are no crosslinks in the crystalline cores, it has been suggested that the decay of the double bond does not result in the crosslinks.
    Zusätzliches Material: 7 Ill.
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  • 42
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 443-444 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 1 Tab.
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  • 43
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 455-476 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The morphology of several series of segmented polyether-urethanes was studied. The “hard” segments contained urethane and urea linkages formed by 4,4′-dicyclohexylmethane diisocyanate (Hylene W) and selected aliphatic and aromatic monomeric diamines (DA). The “soft” segments were composed of oligomeric poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), or both PEO and PPO. For studying the composition-morphology relationships, the molecular weight and relative content of PEO, and the relative content of PPO were varied systematically. Different diamines were used as chain extenders. The methods of wide-angle x-ray diffraction (WAXD), small-angle x-ray scattering (SAXS), polarizing microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) were employed in the investigation. The effects of PEO content on domain formation were very significant. Calculations based on a highly simplified model indicated that, for two adjacent molecules, if two hard segments are associated with each other, the probability for the association of the next two hard segments varies inversely with the third power of soft segment length. Copolymers composed of both POE and PPO displayed enhanced domain and anisotropic superstructure. The phenomenon was interpreted in terms of polymer incompatibility. The effects on morphology of different DA's as chain extenders were tentatively accounted for by the symmetry, hydrogen bonding, and rigidity of the hard segments as well as their incompatibility with the soft segments. The formation and deformation of superstructure were of particular interest. A model was proposed to account for the formation of the resultant anisotropic structure and mechanical properties.
    Zusätzliches Material: 16 Ill.
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  • 44
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 527-532 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Low-density bulk polyethylene was subjected to gamma radiation doses between 0.1 and 100 megarads. Surfaces produced by fracture at liquid nitrogen temperatures were studied using scanning electron microscopy. The unirradiated polyethylene and polymer irradiated to 0.1 megarad had spherical units with a diameter of about 0.15 micron lying on the fracture surface. The units lay along the edges of the lamellae and were formed by the fracture that was, therefore, not entirely brittle. Polyethylene irradiated between 1 megarad and 100 megarads exhibited spherical voids, with a diameter of about 0.1 micron in the fracture surface. The voids have been produced either by the evolution of gas in the polymer during irradiation, the most likely mechanism, or as a function of the fracture mechanism only.
    Zusätzliches Material: 4 Ill.
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  • 45
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 567-578 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Radical formation during mechanical degradation of solid poly(2,6-dimethyl-p-phenylene oxide) (PPO) was investigated by electron spin resonance (ESR). The ESR spectrum of PPO fractured at room temperature in air consisted of eight lines with a separation of about 5.5 gauss with g = 2.0043, indicating a small asymmetry. For PPO fractured in liquid nitrogen, a similar spectrum was observed at -196°C in air or in vacuo. These spectra have been identified as belonging to a 2,6-dimethyl-substituted phenoxy radical and thus indicate the occurrence of main-chain rupture. The phenyl radical which was expected to be formed together with a 2,6-dimethyl-substituted phenoxy radical could not be detected, but at temperatures below -46°C a small hump was observed at g = 2.034. By subtracting the spectrum observed after decay of this hump from the original one, the resulting curve was the characteristic asymmetric spectrum of a peroxy radical, which was presumably formed by the reaction between a phenyl radical and oxygen. The radical decay curve showed two stepwise-decaying regions; one located in the temperature region between about -120°C and -80°C where only a small number of radicals decayed, another located in the temperature region from about -30°C to 100°C where almost all mechanically formed radicals decayed. The latter radical decay, which occurred considerably below the glass-transition temperature of PPO, was attributed to the molecular motions associated with the mechanical β* relaxation on the basis of the activation energy and the temperature region.
    Zusätzliches Material: 10 Ill.
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  • 46
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 653-662 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The heat of fusion of poly(ethylene oxide) blocks has been measured by DSC on twelve polystyrene-poly(ethylene oxide) multiblock (AB)n copolymers and two ABA triblock copolymers after conditioning at various times and temperatures. Regardless of the length of polystyrene blocks, copolymers with poly(ethylene oxide) blocks with M̄n = 404 showed no heat of fusion, those with M̄n = 900 almost no peaks, those with M̄n = 1960 small broad peaks, and those with M̄n = 5650 clearly observable peaks. the greatest heat of fusion measured for block copolymers was 60-70% of the value for hompolymer. Small-angle x-ray patterns are given. The relation between crystal growth and block length is discussed.
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  • 47
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 703-714 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Stress relaxation and moduli of elasticity of the composite system crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA)-glass beads were studied dry and swollen in water to equilibrium state over the temperature range 5-170°C. The moduli of the composites in the dry state increased with increasing filler concentration, while those of the composites measured in the swollen state up to the volume concentration of the filler vf′ ≅ 0.15 decreased. In this respect the composites behaved as porous systems, i.e., as polymers with macroscopic defects. This effect was explained as a consequence of weak filler-matrix interaction. The results were compared with the existing theories of moduli of the composite materials.
    Zusätzliches Material: 8 Ill.
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  • 48
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 737-752 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Measurements of dielectric constant and loss, broad-line nuclear magnetic resonance, and differential thermal analysis of concentrated solutions of poly(γ-benzyl-L-glutamate) (PBLG) were carried out to determine the effects of intermolecular interactions on the mobility of the side group and the solvent (dichloromethane or dioxane). Only one dielectric loss peak due to the cooperative motion of the side group and the solvent was found. The activation energy of this relaxation process varied from 3 to 47 kcal/mole with increasing concentration of PBLG from 20 to 100% by weight accompanied with steep increases at about 40 and 80%. This result is explained as due to entanglement of neighboring side groups. In NMR, narrowing of the line was observed near the temperature where the dielectric loss was observed. The glass transition was also observed by differential thermal analysis. From these results it was concluded that the relaxation observed in PBLG solution and in pure PBLG have the nature of primary or α relaxations.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
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  • 49
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 303-320 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The design and operation of an automated light-scattering apparatus for studying structures in polymer films are described. The apparatus has angular resolution of 0.02 and 1.0° in radial and azimuthal angles, respectively. The radial scan can be made over the range of 0.5 (or less) to 90° and the azimuthal scan covers 180°. Time resolution is in the order of milliseconds. The operation, data collection, and reduction are fully automatic. Illustrative data on the crystallization of a low density polyethylene are described.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 50
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Light scattering from polybutene-1 films prepared by tubular extrusion was studied in order to investigate its crystalline superstructure and the deformation mechanism. Analysis of the light-scattering patterns together with electron micrographs, indicate the existence of sheaflike crystalline superstructures. The sheaves are aligned nearly side by side with their axes preferentially oriented perpendicular to the machine direction. The Hv scattering patterns exhibit a “butterfly” appearance. Analysis of the patterns in terms of scattering and azimuthal angles at which the scattering intensity is a maximum yields information on the size and shape of the sheaflike texture. The information should be of importance in studies of anisotropic crystal growth caused by molecular orientation in the melt and of the deformation mechanism of the texture. The deformation behavior should be representative of that of different parts of spherulites, at least qualitatively; the deformation of the texture along the machine and transverse directions corresponds to deformation of equatorial and meridional regions of a spherulite, respectively.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 523-540 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: This paper reports of a study on eutectic solidification of the quasi binary system of unfractionated isotactic polypropylene and the dentritic growing diluent pentacrythrityl tetrabromide. This system was characterized by a eutectic-type experimental phase diagram with a eutectic composition of 68% (w/w) of polypropylene. The eutectic temperature was found to depend on kinetics, and was established by differential scanning calorimetry to be 122 and 102°C at a cooling rate of 0.5 and 32°C/min, respectively. A remarkeable nucleating effect of the primary diluent crystals was observed in the solidification of diluted polypropylene solutions. Here the eutectic horizontal was located at a temperature which was 15°C higher than in the eutectic solutions exceeding the temperature at which the pure polymer crystallized from the melt by 8°C. The eutectic microstructures produced were found to depend on the rate of solidification, which was varied by pulling the polypropylene solutions through a fixed temperature gradient of 3°C/mm at different speeds ranging from 0.2 to 80 mm/hr. At rates lower than 3 mm/hr the polymer and the diluent crystallized simultaneously from the eutectic solution in a uncoupled mode of growth, forming a coarse structure of diluent crystals and isotactic polypropylene spherulites with dimensions of about 0.1 mm. At higher speeds the simultaneous crystallization of the macromolecules and solvent molecules proceeded in a co-operative manner with a nonplanar growth front. A rodlike eutectic microstructure was produced, in which diluent rods, lined up in the growth direction, were dispersed in a polypropylene matrix. The lateral dimension λ1 of these rods were found to depend on the growth rate R in the following way: λ12 R = 10-9 mm3/sec, and ranged from 0.3 to 1.0 μm. This was in accord with values calculated by using the current theory of rod eutectic growth of Jackson and Hunt.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 605-616 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Molecular motions in a series of linear aliphatic polyesters [poly(ethylene adipate), poly(ethylene sebacate), poly(hexamethylene sebacate), and poly(decamethylene 1,16-hexadecanedicarboxylate)] were studied by dielectric measurements. Two loss maxima were observed for each polymer in the temperature range from -196 to about 60°C and in the frequency range from 110 to 105 Hz. The loss maxima of these polyesters, lying between -17 and -38°C at 110 Hz (β-relaxation), are due to the micro-Brownian motions of amorphous main chains. It was found that these β-relaxations are well described by the WLF equation. The loss maxima in the range from -88 to -109°C at 110 Hz (γ-relaxation), are attributed both to local mode motions of main chains in the amorphous region and to motions of the polar groups involved at the chain ends. For the β-relaxation, no simple relation between the methylene sequence length and the loss peak temperature was found. Furthermore, as the methylene sequence length decreased, the effective dipole moment of the polyesters increased gradually. These facts were explained in terms of interchain dipole attraction.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 53
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 641-656 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Samples of isotactic polypropylene (PP) were zone-solidified in temperature gradients up to 300°C/cm at growth rates down to 3 μm/min. Oriented α-type spherulites were obtained only by nucleation. While β nucleation is extremely rare, the β phase is easily initiated by growth transformations along the oriented α front. Since the β phase was found to grow considerably faster than the α phase, the α-to-β transformation points diverge across the sample, interrupting growth of the oriented α fibrils. This causes subsequent nucleation to yield teardrop-shaped α spherulites.Differential scanning calorimetry (DSC) studies of zone-solidified PP show the β-phase to be favored by slow growth rates, high temperature gradients, and large degrees of superheat in the melt - all of which tend to suppress nucleation. Differential thermograms of largely β-PP obtained at a heating rate of 1°C/min show the actual melting and recrystallization of the β spherulites into the α form.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 683-692 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A theory has been developed to explain the jump in the relative modulus of filled polymers near the glass transition temperature Tg and the subsequent decrease in relative modulus at temperatures above the glass transition temperature. The theory is based upon the concept that there are some particle-particle contacts in doublets and in agglomerates containing a larger number of particles. Below Tg motion of particles at the contact points is possible because of the high modulus of the polymer. At Tg particle-particle motion mostly ceases because of the low modulus of the polymer. At higher temperatures, the mismatch in the coefficients of expansion allows some motion to occur at points of contact and slippage may occur at the polymer-particle interfaces, so the modulus decreases. It is shown theoretically and experimentally that both the elastic modulus and the mechanical damping depend upon the nature of the surface of the particles.
    Zusätzliches Material: 6 Ill.
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  • 55
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 715-722 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A model is proposed for the electrical polarization that causes the orientation and, hence, the electric birefringence of a suspension containing single crystals of a poly(ethylene oxide)-polystyrene diblock copolymer or a poly(ethylene oxide) homopolymer. It serves to describe how an electric dipole moment lying in the plane of the single crystal can be induced by protons migrating in poly-(ethylene oxide). The resulting Kerr effect is calculated up to saturating fields, and the observed dispersion of the polarization in high frequency fields is explained as a space charge relaxation phenomenon. The estimated relaxation time agrees satisfactorily with published experimental data.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 733-748 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Human transferrin was examined by analytical density gradient equilibrium centrifugation using a short liquid column and employing an iodinated organic gradient salt. Favorable conditions of low pressure and relatively low ionic strength could therefore be obtained. The short liquid column also permitted the layering of extra salt solution above the protein solution in a liquid equalization stage of each experiment. In this stage the amount of preferentially bound water was determined by measurement of solvation arising from the dissolution of the protein which had been added to the centrifuge cell as freeze-dried material. Since schlieren optics were employed, the refractive index of the macromolecular component in the mixed solution had to be known. This quantity was determined from the refractive index difference of the solvent/solution boundary at the liquid equalization stage of each experiment or, alternatively, by regression analysis of the equilibrium data. The new regression method yielded an anhydrous molecular weight of 78,000 daltons which is the same as the value obtained by the classical density gradient equilibrium method performed under the same conditions. Control experiments showed that the analytical ultracentrifuge cell cannot be regarded as a closed, inert system.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 57
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 767-772 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: We propose a new method for the investigation of molecular motion in polymeric solids. In a mechanical step-function experiment, we thermally stimulate the response to a constant stress. The high resolving power of this technique permits detailed study of the complex retardation modes observed in polymers. As an example, we consider the thermally stimulated creep of low density polyethylene. The experimental resolution of the thermally stimulated creep spectra shows the existence of elementary processes well fitted by the assumption of single retardation times.
    Zusätzliches Material: 2 Ill.
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  • 58
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 795-804 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A simple method of measuring the solubility of gases in polymers at elevated temperatures and high gas pressures is described by direct weighing of the sample after cooling to ambient temperatures. Changes in gas content during cooling which would cause errors are largely prevented by nucleating bubbles throughout the samples immediately prior to cooling, with the effect of making the internal partial pressure of gas equal to the external pressure while the polymer is soft and thus preventing gas flux to or from the sample. Results are given for the solubility of nitrogen in branched polyethylene in the temperature range 130-190°C at gas pressures up to 1,030 bar. A kink in the solubility isotherm at temperatures just above the normal crystalline melting point is believed to be caused by a pressure shift of the melting point. Comparison of the results with previous work by Lundberg et al. suggests a systematic error in the latter which reduced the apparent solubility at higher pressures.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 59
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 837-846 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The melting point and the heat of fusion were measured by differential scanning calorimetry (DSC) as a function of draw ratio for linear polyethylene. Both the melting point and the heat of fusion increased with an increase in draw ratio. The plot of the heat of fusion against the melting point was approximately linear. The linear relation is explained theoretically using the assumption that the increases in the melting point and the heat of fusion are due to the orientation of the amorphous phase caused by drawing. The excess free energy of the amorphous phase derived from the orientation increases the melting point, and the amorphous phase absorbs heat for its randomization at the melting point. Hence for drawn samples having an oriented amorphous phase not only the crystal phase but also the amorphous phase contribute to the heat of fusion.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 907-914 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Although hydrogen gas is about tenfold more soluble in hot-filtered mats of polyethylene (PE) single crystals (SC) than in bulk linear PE, we found that no hydrogen solubility at all could be measured in freeze-dried SC. Despite this, hydrogen gas still exerts a catalytic effect on alkyl radical decay on both the fast and slow first-order decay reactions in the freeze-dried samples. Above 40°C the first-order decay constants of the slowly decaying component decrease with increasing fold period.
    Zusätzliches Material: 4 Ill.
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  • 61
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 955-967 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: It has been previously shown that when rigid poly(vinyl chloride) is extended by fully necking the test-piece, subsequent fracture takes place by a novel mechanism. Surface crazes grow into “diamond” -shaped cavities which slowly expand while retaining their shape. We have now found that this new mechanism is of general applicability to a wide range of plastics which fracture after yielding. Examples are given from polycarbonate, poly(ether sulfone), and poly(methyl methacrylate) broken at elevated temperatures. The form of the diamond cavity is determined by the continuation of plastic deformation in the whole test-piece while the diamond grows bigger. After fracture a characteristic cavity is left behind on the fracture surface which demarcates the zone of slow growth. At a given point, which is generally easily observable on the fracture surface, the crack speeds up. This change is believed to correspond to a situation where enough elastic energy is available to propagate a crack. It is favored, not only by the increase in size of the diamond in the test-piece but also by an increase in the average energy stored per unit volume of material.
    Zusätzliches Material: 9 Ill.
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  • 62
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 987-993 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Thermoluminescence of poly(methyl methacrylate) (PMMA) irradiated with x rays, has been studied in the temperature range 100 to 460°K. Two glow peaks with maxima at 136 and 368°K have been observed. These are analyzed by three methods and the results are compared. Both curves obey second order kinetics and correspond to activation energies of 0.17 and 0.88 eV, respectively. It is possible to identify the centers responsible for the two peaks by correlation with electron spin resonance and optical data obtained for the same samples irradiated under the same conditions. Spectral studies of the emission show that the low temperature peak has its maximum at 365 nm while the high temperature peak has its maximum at 480 nm.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1037-1040 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Materialart: Digitale Medien
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  • 64
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1067-1075 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
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  • 65
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1129-1142 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 66
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1651-1653 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 67
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1267-1281 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 7 Ill.
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  • 68
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1315-1317 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 69
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1339-1345 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1397-1407 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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).
    Zusätzliches Material: 7 Ill.
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  • 71
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1451-1473 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 6 Ill.
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  • 72
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1507-1520 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 13 Ill.
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  • 73
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1647-1654 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1675-1683 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1757-1767 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 9 Ill.
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  • 76
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1837-1861 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 77
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1913-1925 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 78
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 1967-1982 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 14 Ill.
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  • 79
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2027-2031 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 80
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2037-2038 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 81
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2055-2056 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 82
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2087-2093 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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%.
    Zusätzliches Material: 6 Ill.
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  • 83
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2127-2142 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 14 Ill.
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  • 84
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 15 (1977), S. 2185-2199 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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
    Zusätzliches Material: 12 Ill.
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  • 85
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 361-367 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
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  • 86
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 863-869 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
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  • 87
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 889-899 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 4 Ill.
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  • 88
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 947-951 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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).
    Zusätzliches Material: 1 Ill.
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  • 89
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 971-975 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 3 Ill.
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  • 90
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1023-1032 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 91
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 825-834 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 4 Ill.
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  • 92
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 835-850 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 8 Ill.
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  • 93
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 901-908 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 1 Ill.
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  • 94
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1097-1113 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 9 Ill.
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  • 95
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1159-1166 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 4 Ill.
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  • 96
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1201-1214 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1533-1542 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1563-1576 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1591-1602 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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).
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1577-1589 
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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