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  • LUNAR AND PLANETARY EXPLORATION  (717)
  • Physics  (470)
  • 1995-1999
  • 1980-1984
  • 1975-1979  (1,187)
  • 1975  (1,187)
Collection
Publisher
Years
  • 1995-1999
  • 1980-1984
  • 1975-1979  (1,187)
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 127-135 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 2
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 43-57 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 3
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 73-86 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 4
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 137-149 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 5
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 223-241 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 6
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 263-274 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 7
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 333-338 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 8
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 9
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 437-441 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 10
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 477-492 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of 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.
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  • 11
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 533-566 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 12
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 599-605 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 13
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 663-666 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 14
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 675-682 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 15
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1167-1176 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the 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.
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  • 16
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1215-1231 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 17
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1269-1274 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 18
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1333-1346 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 19
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1377-1386 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 20
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1417-1446 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 21
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 22
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1705-1719 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 23
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1783-1787 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 24
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1809-1817 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 25
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1849-1854 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 26
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1871-1879 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 27
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1913-1923 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 28
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1939-1944 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 29
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2129-2134 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 30
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2289-2298 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 31
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2331-2343 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 32
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2385-2390 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 33
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2391-2400 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 34
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 303-321 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 351-359 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 443-444 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 455-476 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 38
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 527-532 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 39
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 567-578 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 653-662 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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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  • 41
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 703-714 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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  • 42
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 737-752 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 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.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1651-1653 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
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  • 44
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 361-367 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Freeze-dried single crystals of unfractionated Marlex 6009 polyethylene were irradiated at various doses up to 100 Mrad. Analysis of the data of the present work and those of others showed that the decay of vinyl groups can be best described by second-order kinetics. The decay rate constant is found to increase with decrease in original concentration of vinyl groups. It has been concluded that the increase in the decay rate constant with decrease in initial vinyl concentration is due to a decrease in crystallinity. Some supporting evidence has been presented for this conclusion.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 863-869 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
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  • 46
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 889-899 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 13C NMR configurational assignments are made for an amorphous polystyrene sample examined at 25.2 MHz and 120°C. The assignments are based strictly on a one-parameter Bernoullian fit that was in satisfactory agreement with the nine observed methylene relative intensities. The methylene regions of the 13C NMR spectra of a polystyrene were examined before and after hydrogenation of the side-chain phenyl substituents. It was concluded that ring current effects have influenced the 13C methylene chemical shifts substantially and are limited largely to contributions from adjacent phenyl substituents. In addition, aromatic substituent parameters are reported that can be used in conjunction with the Grant and Paul parameters for calculating chemical shifts in aromatic hydrocarbons and polymers. Finally, it is concluded that free-radical and n-butyllithium-prepared polystyrenes have essentially atactic structures with meso additions favored over racemic additions by approximately 55/45.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 947-951 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the glass-rubber transition region of viscoelastic behavior of amorphous polymers, it is found that \documentclass{article}\pagestyle{empty}\begin{document}$$J\left( {\rm t} \right) \approx J''\left( {1/t} \right)$$\end{document} is a good first approximation. Here J(t) is the value of the shear creep compliance at time t and J″(1/t) is the value of the shear loss compliance at an angular frequency of 1/t. Previous approximations related the creep compliance to the storage compliance. When J(t) is proportional to tm, where m is a positive constant, J″(1/t) is within 30% of J(t) for m 〉 0.6. Over the entire range, \documentclass{article}\pagestyle{empty}\begin{document}$$ J\left( t \right){\rm } \approx {\rm }J_{\rm d} \left( {{1 \mathord{\left/ {\vphantom {1 t}} \right. \kern-\nulldelimiterspace} t}} \right) $$\end{document} is a better approximation than either of the other two. The relaxation modulus G(t) is hardly ever a good approximation for the loss modulus G″(1/t).
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 971-975 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An adiabatic heat capacity study of poly(diethylsiloxane) confirms that it has a single glass transition occurring at 130°K, the lowest glass transition reported to date for a high molecular weight polymer. The two previously reported glass transitions are first-order thermodynamic peaks whose location is dependent upon prior thermal history. Combination of these data with low-temperature x-ray diffraction indicates that the transitions in this temperature range are related to a crystal-crystal transformation. A crystal melting transition is observed near 270°K. In addition an anomalous rise in heat capacity near 60°K suggests a sub-glass transition of unknown origin.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1023-1032 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Interferometric studies of the diffusion of molecular iodine into polyvinylpyrrolidone (PVP) are described. The diffusion process is observed by means of a holographic microscope which, with a camera, permits holograms to be recorded during the polymer-iodine interaction. The holograms are subsequently used to produce interferograms that monitor the diffusion process as a function of time. Measurements taken from the interferograms indicate that the diffusion mechanism is not purely Fickian and that the diffusing boundary of iodine is characteristic of case II diffusion. The interferograms yield values for average diffusion coefficients as a function of sample thicknesses that range from 2.32 to 9.53 × 10-10 cm2/sec.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 825-834 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: EPR and matrix ENDOR spectra have been examined for polyenyl radicals in γ-irradiated PVF, PVF2, PVC, and PMMA polymers. Proton matrix ENDOR is observed for all four polymers, and fluorine matrix ENDOR for PVF and PVF2. By line shape analysis of the ENDOR spectra obtained under comparable conditions, delocalization diameters for the unpaired electron of the polyenyl radical in each polymer are obtained. These diameters indicate extensive delocalization over 5-7 carbon double bonds for the polyenyl radicals investigated. It is suggested that these conjugated and crosslinked radiation products account for the observed nondevelopment of electron beam resist PMMA material at high radiation charge densities.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 835-850 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A systematic study of the dispersion curves of the refractive indexes of nylon 6 yarns was made. The parameters were the draw ratio and strain. The measurements show that the dispersions of the refractive indexes n∥ and n⊥, parallel and perpendicular to the fiber axis, are equal, independently of draw ratio and strain. The average dispersion equals nF - nC = 109 × 10-4. Consequently, the birefringence is, within experimental accuracy, independent of the wavelength. The refractive indexes and the birefringence show a change in trend at 10-12% strain. This point corresponds to the yield strain in the stress-strain diagrams. The inference is that beyond the yield point the overall molecular orientation must increase less strongly with strain than before. An analysis shows that the Lorentz-Lorenz relation holds for the average refractive index n̄ = ⅓ (n∥ + 2n⊥). So the change in n̄ versus draw ratio is mainly due to the change in density. By applying the Lorentz-Lorenz relation to the change of n̄ on straining, a value of Poisson's ratio (μ) could be derived. The average value found for nylon 6 yarns was μ = 0.48, which means that the density hardly changes with strain.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 901-908 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Improvements in the 13C NMR Grant and Paul parameters as applied to polymers have been obtained by noting that the “corrective terms” can be temperature-sensitive. A corresponding temperature sensitivity was not observed for the primary parameters, α through ∊. Results are given for a hydrogenated polybutadiene and six different ethylene-1-olefin copolymers where the standard deviation between calculated and observed chemical shifts has been improved from 1.04 to 0.30 ppm. Since the “corrective terms” in the Grant and Paul empirical analyses of chemical shifts reflect the conformational character of polymers, it is shown that values for these terms can best be obtained directly from the system under study.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1097-1113 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: After flowing in a dilatometer bulb for a small fraction of the duration of the transformation, a relaxed melt of poly(ethylene oxide) (M̄n = (5.9 ± 0.1) × 103) showed marked increases in isothermal crystallization rate. The extent of increase was greater when flow was imposed at modestly later stages rather than at the earliest stage of a crystallization. Kinetic parameters for the flow-induced crystallizations were obtained via modification of the conventional mathematical treatment of the kinetics of phase change, thereby allowing the analytical resolution of the overall process into flowinduced and quiescent components. Determination of the flow-induced crystallization parameters required independent determination of the kinetic parameters for quiescent crystallizations at that temperature. The Avrami exponents nf which characterized the flow-induced portions of the crystallizations were larger for those instances in which flow was imposed at the more advanced stages of the crystallizations, thus indicating a transition in crystallization mechanism. It is suggested that prior crystallinity present at the time of flow contributed to the crystallization by serving as a source of nucleation sites. However, in light of the experimental procedure employed, values of nf approximating 4 that were obtained are not susceptible to mechanistic interpretations now extant.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1159-1166 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fundamental vibrational frequencies of an isolated chain of trans-1,4-polychloroprene have been calculated. The agreement between the calculated and experimentally observed crystalline frequencies supports the molecular model for the structure of trans-1,4-polychloroprene and the force field employed in the calculations. The results of the normal coordinate analysis indicate that there is essentially no coupling between adjacent translational repeat units of trans-1,4-polychloroprene.
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  • 55
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1201-1214 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experiments were designed to demonstrate that the chemical potential gradient required for liquid transport through swollen network polymer membranes manifests itself as a concentration gradient and that the rate of transport is independent of how this gradient is established. The fluxes of various liquids through a crosslinked rubber membrane were measured in hydraulic and pervaporation modes of permeation. The pressure applied downstream in the latter act simply to fix the activity of the liquid in the downstream membrane surface. The experiments show the flux is a unique function of this activity, and it does not matter how it is established. Sorption data were used to convert these results into a plot of flux versus concentration differential across the membrane which was analyzed by Fick's law using a model for the concentration dependence of the diffusion coefficient. Measured ceiling fluxes for pervaporation for a number of liquids were found to be the same as those estimated from hydraulic permeation data. A simple mathematical representation for an ideal system is used as a pedagogical device to demonstrate the conclusions.
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  • 56
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1533-1542 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low molecular weight PVC polymers of known degree of crystallinity (44% by x-ray diffraction), prepared in the presence of the chain-transfer agents n-butyraldehyde and n-butyl mercaptan, are examined by differential scanning calorimetry in order to ascertain temperatures and heats of fusion. Initial thermal scans are accompanied by large endotherms and appreciable weight losses due to the lability of the terminal groups originating from the chain-transfer agents. However, further successive scans result in approximately invariant endotherms attributable to crystalline fusion. The maximum melting point, about 265°C, exceeds the value for commercial PVC, about 210°C, but is lower than a value deduced for a hypothetical completely syndiotactic polymer, about 400°C. The average heat of fusion ΔHu is 1180 ± 90 cal/mole, and the resultant entropy of fusion is 1.1 cal/deg/bond. The present ΔHu value differs significantly from previously reported values of 660-785 and 2700 cal/mole, based on melting point depression theory, but appears to be concordant with known heats for a series of vinyl polymers.
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  • 57
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1563-1576 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Strain-dependent relaxation moduli G(t,s) were measured for polystyrene solutions in diethyl phthalate with a relaxometer of the cone-and-plate type. Ranges of molecular weight M and concentration c were from 1.23 × 106 to 7.62 × 106 and 0.112 to 0.329 g/cm3. Measurements were performed at various magnitudes of shear s ranging from 0.055 to 27.2. The relaxation modulus G(t,s) always decreased with increasing s and the relative amount of decrease (i.e.,-log[G(t,s)/G(t,0)]) increased as t increased. However, the detailed strain dependences of G(t,s) could be classified into two types according to the M and c of the solution. When cM 〈 106, the plot of log G(t,s) versus log t varied from a convex curve to an S-shaped curve with increasing s. For solutions of cM 〉 106, the curves were still convex and S-shaped at very small and large s, respectively, but in a certain range of s (approximately 3 〈 s 〈 7) log G(t,s) decreased rapidly at short times and then very slowly; a peculiar inflection and a plateau appeared on the plot of log G(t,s) versus log t. The strain-dependent relaxation spectrum exhibited a trough at times corresponding to the plateau of log G(t,s). The longest relaxation time τ1(s) and the corresponding relaxation strength G1(s) were evaluated through the “Procedure X” of Tobolsky and Murakami. The relaxation time τ1(s) was independent of s for all the solutions studied while G1(s) decreased with s. The reduced relaxation strength G1(s)/G1(0) was a simple function of s (The plot of log G1(s)/G1(0) against log s was a convex curve) and was approximately independent of M and c in the range of cM 〈106. This behavior of G1(s)/G1(0) was in agreement with that observed for a polyisobutylene solution and seems to have wide applicability to many polymeric systems. On the other hand, log G1(s)/G1(0) as a function of log s decreased in two steps and decreased more rapidly when M or c was higher. It was suggested that in the range of cM 〈 106, a kind of geometrical factor might be responsible for a large part of the nonlinear behavior, while in the range of cM 〉 106, some “intrinsic” nonlinearity of the entanglement network system might be important.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1591-1602 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Composites with a matrix of poly(2-hydroxyethyl methacrylate) (PHEMA) and 10% by volume of various crosslinked PHEMA polymer fillers (prepared by copolymerization with 0.1, 0.4, 1.0, and 20.0% by weight of ethylenedimethacrylate) of particle size about 1 μm were prepared. Some polymer matrixes were prepared from soluble branched PHEMA (Hydron S), and others by copolymerization, in the presence of the filler with 0.4 and 1.0% of ethylenedimethacrylate as a crosslinking agent. In the case of the uncrosslinked matrix, a linear polymer-crosslinked polymer system, resulted; in the case of the crosslinked matrix, a composite heterogeneous network was formed (in the latter case, the particles of the filler were swollen with monomer during the crosslinking polymerization).Stress-strain, equilibrium, and ultimate characteristics were measured at 3, 10, 25, 40, 60, and 80°C on samples swollen to equilibrium in water (Tg ≈ -50°C) and at 80, 110, and 140°C on dry samples (Tg ≈ 100°C). Depending on experimental conditions, above all on the distance from the main transition region and on whether the polymer is dry or swollen, it was found that the measured hydrophilic composite systems behaves as a filled system (with the polymer filler acting mostly as solid particles, irrespective of the crosslink density) or as a system with crosslink density fluctuations (where both networks, the matrix and the filler, contribute roughly additively to the properties of the system), or finally as defect heterogeneous systems (where the properties depend primarily on the character of the polymer-filler interface).
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  • 59
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1577-1589 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The steady shear viscosity η(k) and the stress decay function \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \eta \left({t,k} \right)$\end{document} (the shear stress divided by the rate of shear k after cessation of steady shear flow) were measured for concentrated solutions of polystyrene in diethyl phthalate. Ranges of molecular weight M and concentration c were 7.10 × 105 to 7.62 × 106 and 0.112-0.329 g/cm3, respectively. Measurements were performed with a rheometer of the cone-and-plate type in the range 10-4 〈 k 〈 1 sec-1. The Cox-Merz relation η(k) = |η*(ω)|ω=k was tested with the experimental result (|*(ω)| is the magnitude of the complex viscosity). It was found to be applicable to solutions of relatively low M or c but not to those of high M and c. For the latter η(k) began to decrease at a lower rate of shear than |η*(ω)|ω=k did; the Cox-Merz law underestimated the effect of rate of shear. The stress decay function was assumed to have a functional form \documentclass{article}\pagestyle{empty}\begin{document}$\tilde \eta \left( {t,k} \right) = \sum {\eta _p \left( k \right)e^{ - t/\tau p\left( k \right)} } $\end{document} where τ1 〉 τ2 〉 …, and the values of τ1, τ2 η1 and η2 were determined for some solutions. The relaxation times τ1 and τ2 were found to be independent of k and equal to the relaxation times of linear viscoelasticity. At the limit of k → 0, η1 and η2 were approximately 60 and 20-30%, respectively, of η and the non-Newtonian behavior was due to large decreases of η1 and η2 with increasing k. It was shown that η1(k) may be evaluated from the relaxation strength G1(s) for the longest relaxation time of the strain-dependent relaxation modulus with a constitutive model for relatively high c-M systems as well as for low c-M systems.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1633-1642 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of five heterogeneous network polymers was prepared from poly(D-glutamic acid) (PDG) and poly(oxyethylene glycol) (PEG), and their dynamic mechanical properties were studied. The content of PDG was fixed at 60% by weight, and the molecular weight of PEG was changed to obtain networks with various crosslink densities. An increase in the PEG molecular weight from 330 to 880 caused considerable broadening of tan δ and E″ curves, and peak temperatures for tan δ and E″ decreased slightly. Curves of tan δ and E″ for PDG-PEG 4000 (indicating a PEG component of molecular weight 4,000) were much broader and the existence of two peaks was recognized. These findings and x-ray photographs suggest that PDG-PEG 330, 570, and 880 give films of fairly uniform phase, but that PDG-PEG 1830 and 4000 give films with two-phase structure. The factors influencing the dynamic mechanical properties in decreasing order of effectiveness are found to be the proportions by weight of PDG and PEG, the compatibility of PDG with PEG, the crosslink density, and the concentration of free carboxyl groups. The infrared spectra of these polymers indicate that at least part of the PDG component retains the α-helix conformation.
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  • 61
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    Notes: Mixtures of crosslinkable ethylene-propylene terpolymer with saturated ethylene-propylene copolymer (molecular weights 3.6, 16.7, and 45 × 104) containing up to 50% by weight of copolymer were crosslinked by sulfur, leaving the saturated copolymer unattached and free to reptate in the terpolymer network. Stress relaxation in small simple elongations (stretch ratio about 1.15) and dynamic Young's modulus at frequencies from 3.5 to 110 Hz were measured at temperatures from 10 to 50°C. Comparison with the properties of the terpolymer crosslinked without added copolymer showed contributions to stress relaxation and mechanical loss attributable to the unattached species. The time required in stress relaxation for the portion of the modulus attributable to the unattached species to decay to half its plateau value, t1/2, is approximately proportional to the 3.5 power of the molecular weight; t1/2 appears to be slightly smaller for networks containing 50% than for those containing 25% unattached component.
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  • 62
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1721-1735 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The behavior of narrow molecular weight distribution polymers has been investigated under uniaxial extension at constant deformation rate and at constant stress. It has been established that up to rupture these polymers behave as linear viscoelastic bodies. A detailed investigation of the rupture phenomenon has shown that the rupture of fluid polymers is due to their transition to the rubbery state at critical deformation rates, with the result that they disintegrate like quasi-cured rubbers. The effect of the temperature and the molecular weight on the critical conditions of rupture has been described in terms of viscoelastic relaxation.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1747-1759 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The P-V-T relation and the heat capacity of a chlorinated polyethylene vulcanizate were measured. Several tests on the validity of thermodynamic treatments of the α relaxation process and the glass-transition temperature were performed by using dielectric properties. From a study using excess variables, it was shown that the entropy theories represented by the equations of Goldstein and Adam-Gibbs' were slightly better than the free volume theory represented by Doolittle's equation. However the study provided no distinction between the two entropy theories. Some tests were also performed on the pressure dependence of the glass-transition temperature, dTg/dP, and on H*V/H*V where H*V is the isochoric activation enthalpy and H*P is the isobaric activation enthalpy. Here, too, the entropy theories were better than the free volume theory. Goldstein's expression gave values of both dTg/dP and H*V/H*P closest to those from the dielectric experiments. The Adam-Gibbs' equation gave a temperature dependence for dTg/dP and H*V/H*P most similar to those from the experiments.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1819-1829 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This is the first paper in a series dealing with the crystallization of high polymers at elevated pressures. Through an extension of the thin-film technique using osmium tetroxide staining, the measurement of lamellar growth kinetics at high pressures as well as the observation of micromorphological changes has proved possible. Three different morphological species of cis-polyisoprene have been detected in the pressure-temperature plane. A review is given of the conditions governing their formation and the growth kinetics of lamellar crystals are discussed in detail. Secondary nucleation theory is obeyed, the major effect of pressure being to alter the kinetics through the thermodynamic transitions. Variations in lamellar thickness with pressure may be explained simply in terms of the elevation by pressure of the equilibrium melting point.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1855-1857 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1881-1891 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A terpolymer of butadiene-styrene-vinylpyridine has been crosslinked by addition of iron chloride. Differential enthalpic analysis gives evidence of a two-phase system. Electron microscope studies at 0.1 and 1 MeV show the existence of precipitates. The majority of these ironrich aggregates have diameters less than 100 Å. Their form is polyhedral but very nearly spherical. No crystallinity has been detected inside the clusters. Thus the existence of strong interactions as in crystals of FeCl3 hydrates is excluded.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1945-1957 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It has been presumed in studies of the orientation of low-density polyethylene and its time dependence that the degree of crystallinity remained constant with elongation and did not vary with time following elongation. This paper represents a test of this hypothesis by several methods. The change in crystallinity accompanying stretching has been followed by a modification of an x-ray method for uniaxial orientation proposed by Ruland in which diffraction peaks are resolved into crystalline and amorphous components and their respective areas are determined by two-dimensional integration over both the Bragg angle and the azimuthal angle of diffraction. The weight-fraction crystallinity is then determined from the ratio of the weighted crystalline area to the total area. There appears to be no significant variation in crystallinity up to 50% sample elongation for both slowly and rapidly stretched samples at room temperature. The dynamic crystallinity change accompanying small amplitude vibration has also been determined by the dynamic x-ray diffraction technique and found to be negligible over a wide range of frequency. The degree of crystallinity has also been evaluated from the absolute infrared absorbance of crystallinity-sensitive bands and has also been found to be independent of elongation at room temperature up to 80% elongation. Changes have also been observed by this method during relaxation at constant length following rapid extension and have also been found to be negligible. These results also indicate negligible changes in rotational isomer population. Consequently, we conclude that changes observed during relaxation and vibration arise from orientational changes rather than changes in the degree of crystallinity.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2103-2115 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A theory pertinent to the nucleation of polymer-diluent systems for molecules of finite molecular weight has been developed. These results have been applied to the crystallization from polyethylene-α-chloronaphthalene mixtures using molecular weight fractions of polyethylene ranging from 4,000 to 250,000. This analysis is carried out over the composition range extending from pure polymer to a polymer fraction of 0.30. According to this theory, the interfacial basal free energy decreases as either the molecular weight or diluent concentration decreases.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2155-2171 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of diluent on molecular motions and glass transition in the polystyrene-toluene system was studied by means of dielectric, thermal, and NMR measurements. Three dielectric relaxations were observed between 80 and 400°K. On the basis of NMR measurements on solutions in toluene and in deuterated toluene, relaxation processes were assigned to segmental motions of polystyrene, rotations of toluene, and the local motions of polystyrene and toluene in order of appearance from the high-temperature side. The concentration dependence of the relaxation strength and of the activation energy for the primary relaxation (that at the highest temperature) show a step increment at about 50% by weight. The activation plots for the primary process were expressed by the Vogel-Tamman equation. With this equation, the temperatures at which the mean dielectric relaxation time becomes 100 sec is determined. This agrees well with the glass-transition temperature Tg and hence Tg in concentrated solution is expressed by \documentclass{article}\pagestyle{empty}\begin{document}$$ T_g \approx \frac{{ {B} }} {{ {A + 3} }} + T_0 $$\end{document} in terms of the parameters A, B, and T0 of the Vogel-Tamman equation. The values of A and B are, respectively, about 12 and 0.65 and independent of the concentration. The physical meaning of these parameters is discussed.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2247-2250 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2259-2274 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Previous studies on the fold surface of polyethylene single crystals by means of selective degradation with ozone, together with associated GPC analysis, have been taken further. This refined method led to improved accuracy and reproducibility which enabled new and more quantitative information to be obtained than was possible earlier, and this in turn has led to new conclusions as regards the nature of the fold surface. The postulated picture of the existence of a distribution of fold lengths has received further support together with much additional information about the nature of the distribution itself. Also, differences in this respect between different crystal types have become apparent. The salient feature of the newly mapped distribution is that the majority of the folds terminate within closely defined limits with one minority fraction protruding beyond this level while another is buried within the crystal interior. The protruding folds become progressively looser and can be visualized as collapsed chains on the top surface while the folds which are buried more deeply become gradually sharper when progressing towards the crystal interior. The data on which these conclusions are based can be expressed in quantitative terms by which it could be assessed that there are differences between crystals formed at 90°C and 70°C the latter having a larger proportion of loose folds along the top surface of the crystal. A reasonable agreement between results of GPC and low-angle x-ray analysis gives support to these conclusions.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2313-2320 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the effect of drawing on the glass transition temperature Tg of amorphous polycarbonate was carried out. The Tg attains a maximum at a draw ratio in the range from 1.6 to 2.0. The relationship between the change of structure and Tg is discussed in terms of the configurational entropy and the rate of molecular motion in local mode relaxation. The variation of Tg with drawing may be explained by using the iso-entropy theory. The frequency of the maximum in the dielectric loss fmax and the dielectric relaxation strength Δε of the β mechanism changed with drawing in the same way as that of Tg. Based on the parallel behavior in these results, it is reasonable to consider that the β process of local mode relaxation of polyesters such as PC and PET reflects the structure of the glassy state.
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  • 73
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2345-2355 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The energetics of kinks in polyethylene have been investigated by means of conformational energy calculations on crystalline arrays of C14H30, C18H38, and C22H46. All of the parameters required for assessment of relaxation effects by site theory were calculated including the static defect energies, barriers to defect reorientation, and site strains. Up to two deformable coordination shells in the surrounding lattice were included. In the energy minimization calculations, all molecular internal degrees of freedom were allowed to participate. The effects of chain mismatch along the C axis at large distances from the defect were calculated from a continuum theory. The static defect energy is calculated to be 6.6 kcal/mole for C14H30, and the barrier for reorientation of right-handed to left-handed kinks is 10 kcal/mole. The barrier to “unkinking” to the nondefect state is 2 kcal/mole. The strain induced by the defect is largely a shear in the {0 0 1} plane in the 〈1 1 0〉 direction. It is concluded that although the barrier to reorientation is consistent with kink reorientation contributing to the γ process the predicted intensity rules out any but a very weak contribution to the total process.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2253-2257 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 19-34 
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    Keywords: Physics ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Experiments were performed to determine the effects of strain rate, temperature, and pressure on the flow stress of polyethylene and Lexan polycarbonate deformed in shear. The results were analyzed to determine the activation enthalpy and the shear and dilatation activation volumes of the rate-limiting mechanism of the deformation process. Results show that the activation event involves a volume containing several monomer units and that this volume must dilate by as much as 7% during the activation event. The activation enthalpy was approximately 2.5 × 10-12 erg for polyethylene and 1.1 × 10-12 erg for polycarbonate. The rate-limiting mechanism for polyethylene seemed to be unchanged by plastic strains of up to 250%.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 59-72 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The stress-strain relation is analyzed in terms of the gyration tensor \documentclass{article}\pagestyle{empty}\begin{document}$$S^{\alpha \beta } = N^{ - 1} \sum\limits_{i - 1}^N {x_i^\alpha x_i^\beta } $$\end{document} where the sum is over all N atomic groups comprising the elastomeric material. All groups are taken for convenience to have the same mass. This tensor is linear in the strain, and furthermore it may be evaluated from a configuration integral. The definition of the strain by use of Sαβ gives new insight into the connection between statistical and continuum mechanics, and further clarifies the significance of “affine deformation.” Stress components are obtained as derivatives of the (Helmholtz) free energy A with respect to the invariants of Sαβ. The first invariant is just the radius of gyration S2 of the network, and the dependence of A on S2 alone provides a basis for analysis of stress-strain isotherms.
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  • 77
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 113-126 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Calcium thiocyanate is appreciably soluble in “Phenoxy” polymer. Solutions of this salt have significantly different physical properties compared to the pure polymer. The glass-transition temperature Tg is increased, and the kinetics of the glass transition are affected. The melt viscosity and its temperature dependence are increased. The viscosity changes are predicted from the changes in Tg and thermal expansion coefficients, in contrast to ionomers, in which clustering or domain formation cause viscosity to increase. Mechanical properties of the glassy polymers are also affected by the presence of dissolved salt. The most striking effect is an increased resistance to stress cracking by polar organic liquids. This may be related to the Tg increase, or to changes in solubility parameter, as indicated by insolubility of the salt solutions in solvents for the pure polymer. Increased water sorption and electrical conductivity are also results of salt incorporation.
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  • 78
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 163-175 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A generalization of the radiation-pressure theory of thermal diffusion in liquids explains the genesis of the forces acting in a condensed phase when heat flows through it. The analytical expressions obtained make it possible to connect such forces originated by the radiation pressure of thermal waves with the transport of matter taking place in solutions or suspensions of particles and also with the ultimate result of this transport, that is, the steady-state concentrations of the dispersed phase in the hot and in the cold regions of the nonisothermal solution. The form in which the theoretical results are laid down lends itself to direct and unambiguous experimental verification. The confrontation with a few data found in the literature lends support to the theory.
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  • 79
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 243-251 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pressure dependence of the specific heat of poly(methyl methacrylate), polystyrene, and atactic and isotactic polypropylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300°K and in the pressure range 0-37 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, while the specific heat decreases. The pressure dependencies are most pronounced at low pressures. The results are compared with other experimental results and with theoretical calculations.
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  • 80
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1467-1479 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new method is suggested for the experimental determination of the dependence of the relaxation times on the temperature in dielectrics for which the time-temperature superposition principle is valid. The method makes possible the determination of this dependence for a separate relaxation process (for instance, for the β-relaxation process) over a wide temperature range by means of comparatively simple mathematical operations which are only slightly sensitive to experimental errors. Two or more discharge-current curves, measured with temperatures increasing in an arbitrary way with time, are used for this purpose.
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  • 81
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Heats of mixing of methanol with butyl isobutyrate and with oligomers of butyl methacrylate (monomer to tetramer) having a butoxyl group on one chain end have been measured. To discuss the effect of hydrogen bonding on the heat values, it is appropriate to correlate the heat per mole of binding sites with the binding site fraction. This dependence can be described by a single curve for all oligomers studied, in contrast to the results obtained in a previous paper for the same oligomers with chloroform. This fact suggests that the binding parameters for methanol are not influenced by the degree of polymerization.
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  • 82
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1603-1611 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experiments on electro-osmosis of water through a cellulose acetate membrane have been reported and the data analyzed in the light of nonequilibrium thermodynamics. The linear phenomenological equations have been found to be valid. Study of the directional dependence of phenomenological coefficients has revealed the anisotropic character of the membrane. Efficiency of energy conversion for both electro-osmosis and streaming potential has been calculated and the results have been analyzed in the light of thermodynamic theories.
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  • 83
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2241-2245 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 84
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2221-2235 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rotational isomeric state theory was used to study the unperturbed dimensions 〈r2〉0 of poly(methylphenylsiloxane) (PMPS) chains [Si(CH3)(C6H5)—O—]x as a function of their stereochemical structure. The required conformational energies were obtained from semi-empirical, interatomic potential energy functions and from known results on poly(dimethylsiloxane). PMPS chains were found to differ from monosubstituted and disubstituted vinyl chains primarily in the larger distance of separation between groups in conformations giving rise to “pentanetype interactions.” In PMPS, the relatively large distance of separation, 3.8 Å, makes such in teractions attractive, particularly in the case of two phenyl groups; in contrast, such interactions are strongly repulsive at the ∼2.5 Å separation characterizing vinyl chains. According to the calculated results, PMPS chains are very different from vinyl chains in that increase in isotacticity should cause a significant decrease in 〈r2〉0 and increase in d ln 〈r2〉0/dT. Comparison of theory with experimental results in the literature suggests that PMPS polymers which have been studied in this regard must have been significantly syndiotactic in stereochemical structure.
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  • 85
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2275-2280 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An association of reaction products was observed in the course of GPC analysis of ozone treated chain-folded single crystals of polyethylene which, however, could be eliminated by washing with water. This recognition proved to be important for quantitative studies of the fold surface relying on oxidative fold cutting and should be of interest for studies of oxidative degradation phenomena for their own sake. With the association products appropriately removed, the random fold cutting mechanism could be more closely verified than was possible before. Anhydride linkages are suspected as the source of the association.
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  • 86
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 2321-2329 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Parameters characterizing the interaction of nonidentical polymer molecules in dilute solutions of mixtures of two polymers have been defined on the basis of Stockmayer's theory of light scattering in multicomponent systems. Various procedures for evaluation of the interaction parameters from experimental data have been compared. Specific features of the investigation of such interactions are demonstrated with the scattering behavior of the system polystyrene-poly-(methyl methacrylate)-dioxane.
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  • 87
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1-7 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It has been suggested that transverse sectioning of natural cellulose fibers can be used to test ideas about microfibril structure. This proposal has been examined theoretically and numerical calculations of the weight-distribution curve of sectioned chains are given for several different models. These calculations illustrate the effects that different types of chain folding have on the sectioned size distribution. The difficulties involved in the practical execution of this type of experiment are discussed and it is concluded that fiber-sectioning experiments described in the literature do not disprove the folded-chain hypothesis.
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  • 88
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 35-41 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Graessley's entanglement theory of viscosity modified by a frictional viscosity parameter ηfric is applied to data on solutions of polystyrene in diethyl phthalate at various concentrations and different temperatures. All the data modified give a single master curve over the entire rates of shear, as obtained previously with polydimethyl-siloxanes of various molecular weights and their solutions of various concentrations. The zero-shear viscosity η0, the upper Newtonian viscosity η∞, and ηfric are compared. Three activation energies for flow are estimated from η0, η∞ and ηfric, and are compared. The result suggests that the flow behavior in the upper Newtonian region is much more dependent on ηfric than on the entanglement viscosity term ηent. The ratio of zero-shear entanglement viscosity ηent,0 to ηfric can be used as a measure of the non-Newtonian behavior of the present solutions. Non-Newtonian behavior of the investigated polymer solution becomes appreciable at about ηent,0/ηfric = 2.5. These results are in agreement with previous conclusions based on comparison between η0, η∞ and ηfric for polydimethyl-siloxanes and their solutions.
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  • 89
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 95-112 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity of a number of molten polystyrenes and polypropylenes obtained in various ways from solutions is found to be very strongly dependent on the history of dissolution of the polymer (the concentration of the solution and the “goodness” of the solvent), and on the presence of certain organic oligomeric compounds in very small amounts. The viscosity of the melt may be orders of magnitude less than that of the original samples. The present discussion of these effects is based on the concept of structure formation in amorphous polymers. The structure formed on the solution appears to be very stable with respect to heating and prolonged standing at elevated temperature, although it (and hence the viscosity) strongly depends on the initial concentration of the solution and the nature of the solvent. The role played by additives, present in amounts of small fractions of a percent, is accounted for by the fact that the melt retains the microheterogeneity of the medium. The material moves without its micromosaic structure being disturbed, and the role of the additives is reduced to surface (with respect to structural elements) phenomena.
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  • 90
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 151-162 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By neutron inelastic scattering, a complex low-frequency spectrum is obtained for PET. This is attributed to the complicated structure of the monomer unit, a large number of intramolecular modes being possible. Most of them were identified using infrared and Raman data. Some indication of the presence of intermolecular modes below 200 cm-1 was found in the dependence of resolution and intensity on temperature in this frequency domain. The existence of these intermolecular modes was further supported by the spectra obtained from oriented or annealed crystalline samples.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 203-222 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experiments have been carried out, in connection with those mentioned in Part I of this series, with the general aim of checking some predictions of the radiation-pressure theory of thermal diffusion in the case of macromolecular liquid solutions and in particular with the intent of establishing the dependence of the Soret coefficient on molecular mass of the dispersed particles.The results confirm the dependence of Soret coefficient on the shape and on the mass of the particles. The analytical expressions obtained by the radiation-pressure theory of the phenomenon constitute a satisfactory description of the thermodiffusive behavior of such complex systems. The inner constitution of the particles determines the intensity of the radiation pressures exherted by thermal waves; the molecular cross section determines the total force acting on each particle, while the spatial conformation determines the ratio between mass and cross section and at the same time also the hydrodynamical behavior of a particle within the liquid. All these parameters concur in the phenomenon of thermal diffusion, in the way specified by the radiation-pressure theory of thermal waves, as proved by our experiments.The possibility of a characterization of macromolecules and supermolecular particles dispersed in a liquid on the basis of their thermodiffusive behavior is demonstrated.
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  • 92
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 275-284 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two different polybenzimidazole (PBI) samples have been investigated in order to correlate the differences in molecular weight distribution (MWD) with changes in the elastic modulus and strength of undrawn and drawn fibers. It has been found that within the weight-average molecular weight range (7,000 ≤ Mw ≤ 13,000) there was no obvious correlation with Mw and Mn. However, one sample had a narrow unimodal molecular weight distribution and the other a wide bimodal molecular weight distribution. The small percentage of high molecular weight present in the latter sample gave its fibers better mechanical properties. X-ray diffraction studies showed that the orientation in both drawn fiber samples was equal. This isolated the effects of the molecular weight distribution on mechanical properties.
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  • 93
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 323-331 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to ascertain whether the crystal core of irradiated polyethylene single crystals is free from crosslinks - as would follow from the results of Part I - the fold surface of irradiated single crystals was shaved off with ozone and the resulting product examined by GPC for molecular weight. It was found that on ozone degradation the entire material, which had been insolubilized by radiation-induced crosslinking, has become soluble hence became available for the GPC analysis. The chromatograms displayed the same peaked development with degradation as the unirradiated crystals leading eventually to single traverse dicarboxylic acids. This proves the absence of crosslinks within the crystal interior of the material as examined by GPC. The appearance of some additional low molecular weight material, is attributed to scission at the radiation-induced double bonds due to ozone which eliminates the possibility of the existence of crosslinks within the lattice such as might provide scission sites for ozone. The conclusion could therefore be reached that, to the extent assessable by our GPC test, there are no radiation-induced crosslinks within the crystal lattice, hence the crosslinks produced must be entirely confined to the fold surface region of the crystals.
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  • 94
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 369-386 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Results of experiments on short lengths of nylon 66 and PET monofilament specimens, subjected to lateral compressive force between two parallel platens, are described. In the experimental procedure the change in the compressed diameter and the area of contact were determined as a function of the applied force. From these data elastic moduli in lateral compression were estimated. The load-deformation behavior beyond the elastic range exhibited a yield-like phenomenon. SEM examination of the deformed specimen suggest the possible modes of deformation in the post-yield behavior. It is inferred that the yield occurs due to concentration of deformation along the maximum shear planes. The deformed specimens also show specific forms of fracture initiation and growth.
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  • 95
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 419-429 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The failure properties of crosslinked elastomers are influenced by variables such as the test rate, test temperature, chemical nature of the elastomers, degree of crosslinking, etc. For an elastomer with a fixed degree of crosslinkingthe time dependence of both the stress- and strain-at-break, when determined as a function of the test rate and test speed, can be correlated using a time-temperature shift such as the WLF aT shift factor. When a similar study is carried out with a sample having a different degree of crosslinking, the time dependence of both the stress- and strain-at-break is shifted along the time scale. It is demonstrated here that the time dependence of failure obtained as a function of the degree of crosslinking can be superposed on a master curve by the use of a time shift factor whose value depends directly on the degree of crosslinking.
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  • 96
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 445-453 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The depolarization thermocurrents (DTC) from polyethylene isophthalamide are studied below the glass-transition temperature. The “entire” DTC spectrum is analyzed in terms of a continuous distribution of relaxation times; the corresponding distribution function is very close to that which fits data deduced from bridge measurements.The complex DTC spectrum can be experimentally resolved into single relaxation time processes. The analysis of each “elementary” DTC peak yields dielectric dispersion and relaxation time which allow one to calculate the frequency variation of the complex dielectric constant. The corresponding Cole-Cole plot is in good agreement with that deduced from studies of the “unresolved” γ relaxation.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 509-525 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Shear-band growth velocities have been determined as a function of stress and temperature in polystyrene. The results demonstrate that shear bands can propagate under isothermal conditions; an adiabatic temperature rise at the shear band tip is not necessary for continued localization and growth of the band. The velocity is stress activated with a shear activation volume of 4600 Å3 and thermally activated with an activation enthalpy of 2.8 eV. Comparison of these values of the activation parameters with those for bulk shear flow in polystyrene indicates that the shear band propagation is controlled by the plastic strain rate of the glassy polymer immediately ahead of the tip of the band. Argon's molecular kink model of the elemental deformation process is consistent with measured values of the activation parameters whereas Bowden and Raha's dislocation model is not. The shear bands grow at an angle of ca. 38° to the axis of compression, and if the direction of compression is altered, the shear bands will change direction so as to maintain the 38° angle. Current explanations can not quantitatively account for the large deviation of the shear bands from the 45° plane of maximum shear stress.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 765-774 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To investigate the morphology of unoriented poly(ethylene terephthalate) (PET) films and the selective character of the aminolysis of PET, 67% crystalline polymer samples were degraded with 40% aqueous methylamine at room temperature. The aminolyzed PET samples were subjected to gel permeation chromatography (GPC), viscometry, electron microscopy, and small-angle x-ray diffraction (SAXD). Weight loss and density crystallinity measurements were also made.After 24 hr of aminolysis, the amorphous regions and chain folds were completely removed. The long molecular chains in the semi-crystalline polymer were reduced to monodisperse rods having a molecular weight of 1,800. The corresponding lamellar thickness was calculated to be 101 Å, consistent with the x-ray diffraction and electron microscope (EM) measurements. The EM photographs of “stripped” crystals show the lamellar structure previously found for other selectively degraded polymeric materials. The weight of crystalline debris remaining was consistent with the initial crystallinity. After degradation the crystallinity as determined by density was 96%.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 799-813 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been carried out of the changes in the x-ray diffraction patterns which occur when oriented fibers or tapes of poly(trimethylene terephthalate) (3GT) and poly-(tetramethylene terephthalate) (4GT) are subjected to mechanical tensile stress. Although the polymers show very different behavior in detail, in both cases comparatively large reversible lattice strains are observed (∼ several %). The diffraction pattern of 3GT changes monotonically with increasing macroscopic strain, suggesting that the lattice responds immediately to the applied stress, and deforms as though it were a coiled spring. In 4GT, on the other hand, there is no detectable change in the x-ray diffraction pattern at low macroscopic strains, i.e., low values of the applied stress. At higher stresses, changes in the pattern occur which suggest a definite change in the crystal structure. Finally at the highest values of applied stress, the lattice deformations cease to increase. A preliminary discussion is presented of the relationship of these x-ray diffraction results to the mechanical stress-strain behavior.
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    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 859-861 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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