AbstractStatistical mechanical averages of vectors and tensors characterizing the configuration of amylose chains have been calculated. These quantities are expressed in the reference frame affixed to the first glucose unit, the x axis being situated along the O(4)—O(1) virtual bond vector, and the Y axis in the plane of the virtual bond and the O(4)—C(4) bond. The persistence vector a as defined by the average of the end‐to‐end vector r converges slowly to the limiting persistence vector a∞ with increasing chain length. Configurational averages of the Cartesian tensors formed from the displacement vector ρ = r − a have been computed up to seventh rank according to the generator matrix method. The density distribution functions Wα (ρ) evaluated for xu = 40 by using the three‐dimensional Hermite polynomial expansion truncated at the term involving the tensor of seventh rank are approximately cylindrically symmetric about one of the principal axes of the second‐moment tensor <ρ×2. The density distribution function Wα(ρ) is slightly asymmetric even for xu = 80.
AbstractFar‐infrared spectra of a series of un‐neutralized and neutralized lightly sulfonated polystyrenes with varying sulfonation levels have been investigated to seek spectroscopic evidence for microphase separation known to control the physical properties of these polymers. Broad, strong absorbance bands, not found in the spectrum of unmodified polystyrene, are observed in the spectra of the sulfonated analogs. The effects on the far‐infrared spectra both of sulfonation level and of the mass and charge of the neutralizing cation are discussed in terms of cation motion and the formation of ion‐rich domains.
AbstractThe diffusion of organic solvents in concentrated polymer solutions often deviates from the predictions of Fick's second law, especially when the solution is in the glassy state; such behavior is called anomalous or non‐Fickian. This paper analyzes the one‐dimensional sorption of a solvent into a concentrated polymer solution under a small driving force. The treatment includes the effect of an entanglement network on the process as postulated by Thomas and Windle. The deformation of the entanglement network during sorption creates a normal stress on the solvent equivalent to an osmotic pressure. Including the osmotic pressure gradient in the driving force for solvent diffusion leads to a linear, third‐order partial differential equation for solvent concentration distributions. By evaluating the physical constants in the theory for the system methyl acetate/poly(methyl methacrylate) at 30°C the treatment is shown to predict the anomalous characteristics found experimentally.
AbstractMeasurements of sorption and diffusion of a tribasic acid dye in nylon 6 membranes in the presence of NaCl are reported and critically analyzed by the dual‐mode sorption and diffusion models consisting of either simple partition plus ion exchange, or simple partition plus “Langmuir” modes. It is shown that the former treatment, which is the physically more realistic one, also provides a generally better fit to the data.
AbstractSorption and diffusion of toluene vapor in linear polyethylene with mass‐fraction crystallinity between 0.48 and 0.82 and draw ratios λ up to 10 have been studied at 30°C. The sorbed concentration in the amorphous phase Ca is little affected by crystallinity, indicating that the free‐volume fraction is roughly the same for all isotropic samples. However, the diffusion path becomes more tortuous with increasing crystalline content, thereby leading to a sixfold drop in the zero‐concentration diffusion coefficient D0. Drawing has more drastic effects, reducing Ca and D0 by factors of 4 and 60, respectively, as λ increases to 10. These large changes result from the transformation of the initially spherulitic material into a fibrous structure, which is composed of aligned microfibrils with taut tie molecules lying on the outer boundaries. The effects of crystallinity and orientation on the concentration dependence of the diffusion coefficient are also discussed.
AbstractNonintegral indices are found for the extra meridional reflections in the x‐ray diffraction of drawn polyoxymethylene. The index of one of the extra reflections is estimated at 00l: l = 2.830 ± 0.003. A new model for the molecular conformation which accounts for the nonintegral indices is proposed. The new model is a helix with defects at constant intervals along the helix axis. The defect is an unwinding of the helix by 20° around the helix axis. This defect is believed to be characteristic of crystals of helical polymers. The interval between the defects is estimated as 18 monomers. The crystal structure with these defects is consistent with precise measurements of the layer line positions.
AbstractOriented films of an aromatic polyester containing a triad ester mesogenic group and a decamethylene flexible spacer were studied by polarized light microscopy, small‐angle light scattering, and polarized infrared spectroscopy to determine the nature of the alignment of the polymer chains, induced by shearing, which is responsible for the banded or striped morphology observed. The stripes are apparently composed of fibrils arranged in a zigzag manner containing polymer chains packed in a highly ordered, parallel alignment at an angle of ±26° to the shearing direction.
Journal of Polymer Science: Polymer Physics EditionVolume 23, Issue 3 p. 601-606 Note Phenyl-group rotation in polystyrene Y. Tanabe, Y. Tanabe Research Institute for Polymers and Textiles, 1-1-4 Higashi, Yatabe-machi, Tsukuba-gun, Ibaraki 305, JapanSearch for more papers by this author Y. Tanabe, Y. Tanabe Research Institute for Polymers and Textiles, 1-1-4 Higashi, Yatabe-machi, Tsukuba-gun, Ibaraki 305, JapanSearch for more papers by this author First published: March 1985 https://doi.org/10.1002/pol.1985.180230315Citations: 9AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume23, Issue3March 1985Pages 601-606 RelatedInformation
AbstractThe effect of the depolarization field in crystallites on the ferroelectric behavior of polymers is discussed on the assumption that the crystallite is a prolate ellipsoid with its major axis directed along the electric field. The theory relates the polarization P and the electric field E in the crystallite to the overall values P and E for the polymer. The determination of the P‐E hysteresis of a crystallite from the P‐E hysteresis is given with examples for poly(vinylidene fluoride) (PVDF) and vinylidene fluoride (VDF)–trifluoroethylene (TrFE) copolymer. The ratio R = J/(Ps − P), with J the switching current density and Ps the saturation polarization of polymer, is proved to be free from the depolarization field effect and the plot of logR against logarithmic time is shown to have merit for characterization of switching behavior. Examples of the curves are given for PVDF and VDF‐TrFE copolymers. The temporal change of local electric field in the unreversed domains in the crystallite in the course of polarization reversal is predicted by the theory and this change is proved to be a significant mechanism of switching acceleration.
The initial slopes and intercepts of Zimm plots of scattering experiments yield the centroidal radius of gyration of the scattering particle. In many cases, it is not possible to measure at sufficiently low angle to obtain accurate initial slopes and intercepts. Errors for missing data can be corrected by using calculated scattering functions as models. Such corrections are given here for polydisperse Gaussian coils.
AbstractHydroxyl‐terminatd poly(triethylene glycol terephthalate) was crosslinked with an aromatic triisocyanate. Birefringence–stress–strain experiments, performed on the networks at 70°C, showed an anomalous increase in the modulus and a downturn in the birefringence–strain isotherms at high elongations. These results suggest that crystallinity is not responsible for the non‐Gaussian behavior of the chains at high extension. The same kind of experiments were performed over the range 20–70°C. Values of the optical configuration parameter Δa of the order of 13.3 × 10−24 cm3 with negligible temperature coefficient were found for these networks. The quantities Δa and d In Δa/dT were calculated by means of the rotational isomeric state model. Better agreement between the theoretical and experimental values of these parameters was found for poly(triethylene glycol terephthalate) than for poly(diethylene glycol terephthalate). Since the polarities of the two chains are similar, intermolecular interactions involving terephthaloyl residues may be responsible for the discrepancies observed between theory and experiment for Δa in aromatic polyesters.
AbstractPhase equilibria of polydisperse rods in solution are studied in terms of the Warner–Flory model. Numerical calculations are made with a Gaussian‐like asymmetric distribution of rod lengths. The aim of these studies is to investigate (i) the dependence of the phase diagram on the shape of the polydispersity distribution function and (ii) the isotropic–anisotropic phase separation within the coexistence range. It is shown that, as a consequence of polydispersity, even for a narrow distribution, the phase diagram is very simple, with only one type of anisotropic phase present. However, within the biphasic range, the properties of the anisotropic phase vary significantly with temperature. At high temperatures, they are essentially governed by steric effects and at low temperatures by both steric effects and soft anisotropic interactions between the rods.
Journal of Polymer Science: Polymer Physics EditionVolume 23, Issue 8 p. 1713-1722 Note Synergism in mechanical properties via epitaxial growth in polypropylene-polyethylene blends R. M. Gohil, R. M. Gohil Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112Search for more papers by this author R. M. Gohil, R. M. Gohil Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112Search for more papers by this author First published: August 1985 https://doi.org/10.1002/pol.1985.180230822Citations: 27AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume23, Issue8August 1985Pages 1713-1722 RelatedInformation
AbstractThe temperature ΘA2 at which the second virial coefficient A2 is zero for ring polystyrenes is 28.5°C in cyclohexane, independent of molecular weight in the range 2 × 104 to 4.5 × 105. This cannot be explained solely by the Candau–Rempp–Benoit theory, which takes into account the effect of segment density on ΘA2 The radius of gyration of a ring is found to be approximately one‐half that of a linear polymer with the same molecular weight. The intrinsic viscosities [η] and intrinsic translational friction coefficients [f] of ring polystyrenes with molecular weights ranging from 7 × 103 to 4.5 × 105 have been measured in cyclohexane at 34.5°C (Θ, the Flory theta temperature for linear polystyrenes) and in toluene (a good solvent). The results are compared with those for linear polystyrene. It is found that the Mark–Houwink exponent is less than one‐half in cyclohexane at Θ. In toluene it is 0.67 compared to 0.73 for linear polystyrene. The hydrodynamic measurements suggest that large rings are less expanded than the linear polymers with the same molecular weight, contrary to many predictions.
Journal of Polymer Science: Polymer Physics EditionVolume 23, Issue 11 p. 2410-2410 ErratumFree Access “Polymer fibers drawn to the limit” First published: November 1985 https://doi.org/10.1002/pol.1985.180231114AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume23, Issue11November 1985Pages 2410-2410 RelatedInformation
AbstractProton spin–spin relaxation times and the Weibull coefficient have been measured as functions of temperature for poly(ethylene terephthalate) (PET) drawn at 50°C in both the amorphous and the semicrystalline (50%) states. Two relaxation times T2a (long) and T2c (short) are observed for all samples. They are ascribed, respectively, to the relaxation of the amorphous and of the crystalline components including highly strained noncrystalline segments. Effects of initial morphology are found for chain mobility in the noncrystalline regions and for the crystal perfection, evaluated from T2a and the Weibull coefficient μc of the T2c‐component, respectively. For all draw ratios, T2a for extrudates prepared from the semicrystalline polymer (C‐50) is short compared to that for preparations from the amorphous (A‐50) polymer. In the A‐50 samples, the perfection of stress‐induced crystals increase with increasing draw ratio. In the C‐50 samples, the crystal orientation increases, whereas the perfection decreases with increasing draw ratio. To improve the crystal perfection, annealing at higher temperature or longer time is required for C‐50 as compared with A‐50. The value of μc correlates well with the change in crystal perfection during deformation and annealing.
AbstractThe D‐E (electric displacement vs. field) hysteresis curve of a ferroelectric polymer is conventionally measured by the Sawyer–Tower method. The effect of the electrical conductance of the polymer on the measured hysteresis curve is theoretically analyzed and a new method is proposed for elimination of the error arising from the conductance. Examples of original and corrected hysteresis curves of vinylidene fluoride–trifluoroethylene copolymer are presented.
AbstractRaman spectroscopy is used to investigate the conformation and packing of isotactic crystalline α‐phase polypropylene compared with lower‐order β‐phase isotactic polypropylene and to study the solution behavior of atactic polypropylene. The high‐frequency region of the spectrum is analyzed in light of a normal‐mode calculation that takes into account the methyl‐group vibrations. This region is sensitive to both chain conformation and packing, and because of the high intensity of the methyl and methylene high‐frequency stretching modes, it can be used to probe small changes in intermolecular or intramolecular order. Differences in the thermal behavior between the two solid isotactic polypropylene samples are explained interms of packing defects which exist in the β‐phase form. In the solution study, we demonstrate that, for molecules in which bands sensitive to intermolecular interactions exist, as is the case of the methyl and methylene vibrations of polypropylene, spectroscopic techniques can be used to estimate the minimum overlap concentration.
AbstractSorption of water in quenched amorphous poly(m‐xylylene adipamide) has been studied at 50°C. The sorption process is nearly Fickian at low humidity. At relative humidities higher than about 58%, however, extremely abnormal behavior, such as a decrease in moisture uptake and a change in appearance from transparent to opaque, is found. From x‐ray diffraction analysis, these changes can be attributed to crystallization. Thermal analysis of moistened samples confirmed that the crystallization is due to a drop in crystallization temperature caused by sorption of water. From the relation between the reduction in moisture uptake and the increase in volumetric crystallinity, it is proposed that the change in moisture uptake is caused by the exclusion of water from the crystalline phase.
AbstractSome years ago, Brather proposed a method for calculation of the real and imaginary parts of the complex dielectric permittivity starting from measurements of isothermal polarization current. This method shows some advantages over the Hamon method, which is normally used. Both methods are applied in this work to the β relaxation of poly(butyl methacrylate). It is concluded that, with the usual accuracy of measurement, a combination of the two methods is advisable; Hamon's method is taken to be a first approximation to that of Brather. Results following the two procedures are compared, and their respective advantages and disadvantages are discussed.
