Journal of Polymer Science Part A-2: Polymer Physics

Journal of Polymer Science Part A-2: Polymer PhysicsVolume 10, Issue 3 p. 571-573 Note Effect of molecular weight on the tensile strength of glassy plastics A. N. Gent, A. N. Gent Institute of Polymer Science, University of Akron, Akron, Ohio 44304Search for more papers by this authorA. G. Thomas, A. G. Thomas Institute of Polymer Science, University of Akron, Akron, Ohio 44304 National Science Foundation Visiting Professor, 1969–70 (on leave of absence from the Natural Rubber Producers' Research Association, England).Search for more papers by this author A. N. Gent, A. N. Gent Institute of Polymer Science, University of Akron, Akron, Ohio 44304Search for more papers by this authorA. G. Thomas, A. G. Thomas Institute of Polymer Science, University of Akron, Akron, Ohio 44304 National Science Foundation Visiting Professor, 1969–70 (on leave of absence from the Natural Rubber Producers' Research Association, England).Search for more papers by this author First published: March 1972 https://doi.org/10.1002/pol.1972.160100314Citations: 71 AboutPDF 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 Volume10, Issue3March 1972Pages 571-573 RelatedInformation

AbstractPast differential scanning calorimetry and dielectric relaxation measurements have established that polystyrene (PS)‐poly(vinyl methyl ether) (PVME) mixtures exhibit a degree of compatibility when cast from toluene, whereas they are incompatible when cast from chloroform or trichloroethylene. The present study reports that toluene‐cast mixtures can be phase‐separated by thermal treatment at temperatures exceeding 125°C. This is true for samples containing 20–80 wt‐% PS. The temperature of phase separation varies with heating rate; isothermal heating times needed to cause phase separation increase rapidly as the temperature approaches 125°C. Reversibility of the phase separation process depends upon such factors as cooling rate, annealing time, treatment temperature, and thermal history. By annealing and/or slow cooling, all thermally phase‐separated mixtures have been brought back to their original state of compatibility. That is, there is no evidence for true irreversiblity of phase separation in thermally treated samples. Quench‐cooled samples remain phase‐separated indefinitely at room temperature, but this is attributed to rapid cooling below the glass transition of the PS. Chloroform‐cast and trichloroethylene‐cast mixtures have not been brought to a compatible state by thermal treatment, even after lengthy annealing and slow cooling steps.

AbstractThe elongational viscosity of dilute polymer solutions must always be measured under nonsteady‐state conditions. To predict the time dependence of this viscosity for a polymer solution in which a constant stretching rate is maintained, a simple model is considered in which the polymer molecules are represented by elastic dumbbells. The non‐Hookean elastic force in the dumbbell is determined by the conformational entropy of the chain. Use is made of Peterlin's approximation which replaces the elastic force by a function of the root‐mean‐square end‐to‐end distance. Application to the transient state is straightforward; it can be extended to include the effect of “internal” chain viscosity by means of approximations that are similar to Peterlin's.

AbstractThe glass transition temperature of systems based on epoxy resin and a number of diamines has been determined by using a torsion pendulum. An equation relating composition and crosslink density with the glass transition temperature has been established which gives reasonable predictions of the glass transition temperatures for systems based on aliphatic or aromatic amines and methylated amines and for systems containing a monofunctional epoxy diluent. The equation may be used to predict Tg for systems with non‐stoichiometric quantities of curing agent and blends of amines. Deviation of the predicted and observed values for Tg is interpreted in terms of differences between definitions of Tg used by other workers and, also the occurrence of competing side reactions during polymerization which lead to additional crosslinks.

AbstractRecent literature reports from three laboratories have treated the refraction correction for the Sofica and a noncommercial light scattering photometer. Our re‐evaluation of the data contained in these reports, as well as our experiments, indicate that the usually cited n2 refraction correction has not been unquestionably established for these instruments. In some cases, imprecise experimental techniques have been used to support this particular form of the correction. In addition, we find the optical system of the Sofica instrument results in the detector seeing vertically past the horizontal edge of the illuminated volume in violation of a basic assumption in the deduction of the n2 correction. Our experiments, as well as our interpretation of recent literature data, support an exponent of less than 2.0 for the Sofica apparatus, which is consistent with an instrument whose detector views outside the illuminated volume. However, the experimental methods available to evaluate the exponent lack the desired precision.

AbstractYoung's modulus and mechanical damping of 15 organic liquids in polystyrene have been measured from 4°K to 250°K. The concentration was generally in the range from 10 to 15%, but the polystyrene–toluene system was investigated over the range from 0 to 16%. Some liquids cause the 40°K damping peak of polystyrene to disappear, other liquids do not. Seven of the liquids which cause the disappearance of the 40°K peak give rise to new large damping peaks at the temperature expected for the secondary glass transition temperatures of the liquids, that is, at 0.77 Tg of the liquids. Some of the liquids produced large unexplained damping peaks at temperatures above the expected glass transition temperatures Tg of the liquids. It is suggested that the γ peak in polystyrene is caused by styrene monomer.

AbstractA theory which relates the change in the strength of absorption to the change in crystal orientation function is presented for the anisotropy of dielectric relaxation for the dipolar orientation change in an oriented crystalline polymer. Experimental measurements are presented for the α dielectric absorption of a stretched ethylene–carbon monoxide copolymer and compared with the orientation of crystals of this copolymer as determined by x‐ray diffraction.

AbstractSulfur‐cured natural rubber and other elastomers subjected to tensile tests at low temperatures and low strain rates are found to swell and “foam” after testing when brought to room temperature. The conditions under which this phenomenon can occur are established and related to load‐extension curves. Free radicals formed during tensile testing are studied by electron spin resonance (ESR) techniques. It is found that the free radicals observed at the low temperatures are stable below the glass transition temperature of the material, and it is suggested that these radicals arise from mainchain fracture occurring during yielding of the material. The subsequent swelling at higher temperatures is found to be due to the expansion of environmental gases absorbed during tensile testing and to the release of hydrogen in certain cases from the materials tested. It is also suggested that yielding of the material which gives rise to these characteristics occurs by crazing of the material; the voids in the craze bands absorbing the environmental gases which subsequently cause the foaming at higher temperatures.

Journal of Polymer Science Part A-2: Polymer PhysicsVolume 10, Issue 1 p. 191-192 Note Polymorphism in nylon 12 M. G. Northolt, M. G. Northolt Akzo Research Laboratories Arnhem, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorB. J. Tabor, B. J. Tabor Akzo Research Laboratories Arnhem, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorJ. J. van Aartsen, J. J. van Aartsen Akzo Research Laboratories Arnhem, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this author M. G. Northolt, M. G. Northolt Akzo Research Laboratories Arnhem, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorB. J. Tabor, B. J. Tabor Akzo Research Laboratories Arnhem, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorJ. J. van Aartsen, J. J. van Aartsen Akzo Research Laboratories Arnhem, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this author First published: January 1972 https://doi.org/10.1002/pol.1972.160100114Citations: 32AboutPDF 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 onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1 C. H. Bamford, L. Brown, E. M. Cant, A. E. Elliot, W. E. Hanby, and B. R. Malcom, Nature, 176, 396 (1955). 10.1038/176396a0 CASWeb of Science®Google Scholar 2 F. H. C. Crick and A. Rich, Nature, 176, 780 (1955). 10.1038/176780a0 CASPubMedWeb of Science®Google Scholar 3 D. R. Holmes, C. W. Bunn, and D. J. Smith, J. Polym. Sci., 17, 159 (1955). 10.1002/pol.1955.120178401 CASWeb of Science®Google Scholar 4 D. C. Vogelsong and E. M. Pearch, J. Polym. Sci., 45, 546 (1960). 10.1002/pol.1960.1204514631 CASWeb of Science®Google Scholar 5 L. G. Wallner, Monatsh. Chem., 79, 279 (1948). 10.1007/BF00899404 CASWeb of Science®Google Scholar Citing Literature Volume10, Issue1January 1972Pages 191-192 ReferencesRelatedInformation

AbstractStatistical radii of gyration, second virial coefficients, and intrinsic viscosities of sharp fractions (M̄w/M̄n ≈ 1.1) of polyisobutylene (PIB) covering a wide range of molecular weight (1.6 × 105 to 4.7 × 106) were determined in isoamyl isovalerate (IAIV) at a number of temperatures ranging from 20 to 60°C, in n‐heptane at 25°C, and in cyclohexane at 25°C by light‐scattering and viscosity measurements. It was found that IAIV at 22.1°C is a theta solvent for PIB. Analysis of the data by the methods described in preceding papers of this series indicated that, except for minor differences, the conclusions derived from similar studies with polychloroprene, polystyrene, and poly‐p‐methylstyrene hold equally for solutions of the typical linear polymer investigated here. In particular, no decisive evidence for the drainage effect was found.

AbstractThe following quantities were measured on a number of ethylene–vinyl acetate (EVA) and ethylene–acrylic acid (EAA) copolymers: (1) the small‐angle x‐ray scattering invariant, (2) the overall density, and (3) the crystallinity. Assuming a two‐phase structure, the separate values of the densities of the crystalline and amorphous regions can be calculated from these data. Of these, the crystalline density is compared with the value obtained from the lattice constants. A systematic difference is observed which is ascribed to the presence of comonomeric side groups in the crystalline regions. For the EVA and EAA samples, their concentration is at least 0.3 and 0.5 times the overall concentration, respectively. The amorphous densities are found to be higher than the values calculated from completely amorphous copolymers by extrapolation procedures.

AbstractPoly(vinylidene fluoride) (PVF2) is currently used to form piezoelectric films. The PVF2 molecule can exist in more than one stable conformation and it has electrically polar groups making the polymer amenable to the electrification processes involved in the formation of the piezoelectric film. The two crystalline forms of PVF2 are distinguishable by far‐infrared spectroscopy. Polarized far‐infrared spectra (1000‐50 cm−1) of uniaxially oriented PVF2 show changes in the strong perpendicular dichroism in a number of absorptions before and after being made piezoelectric. The dichroism is attributed to a structural rearrangement from a staggered trans‐gauche‐trans‐gauché conformation to a planar zig zag conformation. In the latter conformation the permanent dipoles are oriented approximately at right angles to the surfaces of the film and result in an electrically polarized film.

The crystal structure of high pressure phase of polytetrafluoroethylene (PTFE) has been determined by X-ray methods. A high pressure X-ray diffraction apparatus which enables to get the fiber pattern of crystalline sample under purely hydrostatic high pressure at high temperature has been constructed. A small specimen of PTFE fiber was held in the bore of a beryllium window for X-ray. The fiber pattern of high pressure phase of this polymer has been recorded on a cylindrical film at 5500km/cm2, 78°C. It is found that in this phase the molecules have a planar zigzag arrangement different from that of a helix at atmospheric pressure. The unit cell is orthorhombic, with a=8.73 A, b=5.69 A, c=2.62 A. The result of the X-ray diffraction studies agrees with that of the other physical properties of PTFE in high pressure phase.

AbstractThe elastic behavior of composite and interpenetrating network structures composed of non‐Gaussian chains is investigated. The chain probability density given by Nagai is employed utilizing only the leading correction terms for finite chain extensibility. The independent‐network hypothesis, proven valid in Gaussian statistics, is shown to be erroneous in non‐Gaussian systems. Further, it is found that composite networks composed of monodisperse chains are elastically isotropic, whereas a most probable contourlength distribution yields a large anisotropy but in the direction opposite to that observed experimentally for rubber. On the other hand, retention of the independent‐network hypothesis coupled with a most probable distribution successfully accounts for much of the observed anisotropy. Interpenetrating networks are shown to be substantially anisotropic when a most probable contour‐length distribution is employed.

Journal of Polymer Science Part A-2: Polymer PhysicsVolume 10, Issue 7 p. 1397-1400 NOTE Theoretical approach to the assignment of molecular mechanisms for cryogenic loss peaks in polymers S. Reich, S. Reich Department of Chemistry, McGill University, Montreal, CanadaSearch for more papers by this authorA. Eisenberg, A. Eisenberg Department of Chemistry, McGill University, Montreal, CanadaSearch for more papers by this author S. Reich, S. Reich Department of Chemistry, McGill University, Montreal, CanadaSearch for more papers by this authorA. Eisenberg, A. Eisenberg Department of Chemistry, McGill University, Montreal, CanadaSearch for more papers by this author First published: July 1972 https://doi.org/10.1002/pol.1972.160100717Citations: 16AboutPDF 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 onEmailFacebookTwitterLinkedInRedditWechat References 1 D. E. O'Reilly and T. Tsang, J. Chem. Phys., 46, 1291 (1967). 2 J. O. Hirschfeld and J. N. Linnett, J. Chem. Phys., 18, 130 (1950). 3 D. W. McCall, in Molecular Dynamics and Structure of Solids (N.B.S. Special Publication 301), R. S. Carter and J. J. Rush, Eds., Government Printing Office Washington, 1969. 4 V. Frosini and A. E. Woodward, J. Polym. Sci. A-2, 7, 525 (1964). 5 J. W. Crissman, A. E. Woodward, and J. A. Sauer, J. Polym. Sci. A, 3, 2693 (1965). 6 J. W. Crissman and R. D. McCammon, J. Acoust. Soc. Amer., 34, 1703 (1962). 7 K. M. Sinnott, SPE Trans., 2, 65 (1962). 8 K. H. Illers, Z. Elektrochem., 65, 679 (1961). 9 R. G. Saba, Ph.D. Dissertation, The Pennsylvania State University, 1967. 10 M. Baccaredda, E. Butta, V. Frosini, and S. De Petris, Mater. Sci. Eng., 3, 157 (1968/1969). 11 O. Yano and Y. Wada, J. Polym. Sci. A-2, 9, 669 (1971). Citing Literature Volume10, Issue7July 1972Pages 1397-1400 ReferencesRelatedInformation

AbstractThe change in x‐ray diffraction intensity with time following rapid stretching by various amounts is measured for a low‐density polyethylene sample at several temperatures. An appreciable decrease in intensity with time at the meridian of the diffraction from the 110 and 200 planes is observed to occur within the first 5 sec following stretching. The change takes considerably longer times at lower temperatures. By use of a calibration curve, the change in crystal orientation functions for the a, b, and c crystal axes were calculated, and an increase in c‐axis orientation was shown. From the results of birerringence measurements on the same sample, the crystalline and amorphous contributions to birefringence were calculated. It was shown that stretching is initially accompanied by a greater amount of amorphous than crystalline orientation, and that relaxation involves an increase in crystalline orientation accompanied by a decrease in amorphous orientation.

AbstractThree types of domain structures, namely spherical, rodlike, and lamellar, of A‐B and A‐B‐A (or B‐A‐B) block copolymers cast from solutions are discussed on the basis of a criterion that the structures originate at a critical micelle concentration as a result of microphase separation of the block segments and the micelles formed maintain their structures into the solid state without reorganization. It is concluded that the micelles shrink mostly in the direction perpendicular to the interface between the two phases within the micelles because of the appreciable orientation of the block segments in this direction. In other words, the spherical micelle shrinks isotropically to form a spherical domain having a diameter proportional to the 2/3 power of the degree of polymerization (molecular weight) of the corresponding block segment. Rodlike and lamellar micelles, on the other hand, shrink anisotropically to form rodlike and lamellar domains such that the diameter and the thickness of the respective domains are roughly proportional to the 1/2 power of the degree of polymerization of the corresponding block segment.

AbstractIn order to investigate the role of solid morphology on molecular relaxation in crystaline polymers, the effect of melting on the α relaxation in poly(hexamethylene sebacamide) (nylon 610) was measured dielectrically. It was found that the α loss peak was continuous into the melt with respect to location in the frequency‐temperature domain and with respect to the shape of the peak. However, the strength of the process, as measured by the difference in the relaxed and unrelaxed dielectric constants, was discontinuous on melting, the process being much stronger in the melt. These observations are consistent with a two‐phase model of discrete crystalline and amorphous regions. The relaxation takes place in the amorphous regions, and melting creates more of this material but does not greatly after its nature. The correlation of the amount of amorphous material as measured by dielectric relaxation with that infrared from density measurements is discussed for nylon610, polyoxymethylene, and poly(ethylene oxide).

Journal of Polymer Science Part A-2: Polymer PhysicsVolume 10, Issue 7 p. 1401-1405 NOTE Superheating and reorganization on melting of poly(ethylene terephthalate) Arata Miyagi, Arata Miyagi Department of Chemistry, Rensselaer Polytechnic Institute, Tory, New York 12181Search for more papers by this authorBernhard Wunderlich, Bernhard Wunderlich Department of Chemistry, Rensselaer Polytechnic Institute, Tory, New York 12181Search for more papers by this author Arata Miyagi, Arata Miyagi Department of Chemistry, Rensselaer Polytechnic Institute, Tory, New York 12181Search for more papers by this authorBernhard Wunderlich, Bernhard Wunderlich Department of Chemistry, Rensselaer Polytechnic Institute, Tory, New York 12181Search for more papers by this author First published: July 1972 https://doi.org/10.1002/pol.1972.160100718Citations: 30AboutPDF 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 onEmailFacebookTwitterLinkedInRedditWechat References 1 B. Wunderlich, Polymer, 5, 611 (1964). 2 M. Jaffe and B. Wunderlich, in Thermal Analysis, Vol. 1, R. F. Schwenker and P. D. Garn, Eds., Academic Press, New York, 1969, p. 387. 3 H. G. Zachmann, Kolloid Z. Z. Polym., 206, 25 (1965); H. G. Zachmann, Kolloid Z. Z. Polym., 216–217, 180 (1967). 4 M. Jaffe and B. Wunderlich, Kolloid Z. Z. Polym., 216–217, 203 (1967). 5 A. Miyagi and B. Wunderlich, to be published. For preliminary data see preprints of papers presented at the IUPAC Symposium at Leiden 1970, Vol. II, p. 765. 6 A. Miyagi and B. Wunderlich, to be published. 7 B. Wunderlich, in Physical Methods of Chemistry, A. Weissberger and B. W. Rossiter, Eds., Vol. 1, Part V, Wiley, New York, 1971, Chap. VIII. 8 A. Conix, Makromol. Chem., 26, 226 (1958). 9 P. J. Flory, J. Amer. Chem. Soc., 78, 5222 (1956). 10 J. F. M. Oth and P. J. Flory, J. Amer. Chem. Soc., 80, 1297 (1958). Citing Literature Volume10, Issue7July 1972Pages 1401-1405 ReferencesRelatedInformation

AbstractThe enthalpy of dissociation of poly(acrylic acid) and of poly(methacrylic acid) in water and in 0.5N NaCl at 25°C has been measured over a wide range of degrees of neutralization of the polyelectrolytes. In the case of poly(methacrylic acid) the calorimetric data permit the direct evaluation of the enthalpy of conformational transition of the polymer. For this transition, with the aid of standard free energy data derived from potentiometric titrations, the change in entropy was also estimated. The relative accuracy of the thermodynamic data, and the possibility of deriving therefrom information on the mechanism of transitions of the type, globular coils → expanded coils for partially hydrophobic synthetic polyelectrolytes in aqueous solution are discussed.