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  • Physics  (171)
  • Atomic, Molecular and Optical Physics  (22)
  • Wiley-Blackwell  (193)
  • National Academy of Sciences
  • 1970-1974  (193)
  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of radiation-induced grafting reactions. I. Polyethylene-styrene systems (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 10 (1972), S. 259-273 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By means of bromine labeling and ESR, the grafting reactions of styrene onto preirradiated polyethylene have been investigated. Not all the radicals produced by irradiations participate in grafting reactions all together, but they are rendered active bit by bit by the swelling of crystalline parts of polyethylene. The growing rates for polystyryl graft chains at 20°C decrease from 4 monomer units/active site/sec to one-fourth the initial value after 100 min. On the contrary, the average lifetimes increase from 〈103 sec to 〉2.6 × 103 sec. The number-average molecular weight of graft chains also increases with reaction times and rises to 3.5 × 105 after 90 min at 20°C.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.150100123
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of bending and stretching of polyethylene strips on the adsorption of surface-active substances (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 595-603 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The adsorption of tritium-labeled sodium stearate and 35S-labeled sodium dodecylsulfate from aqueous solution on bent and on stretched polyethylene strips was directly measured. The amount of adsorption increased from 2.5 to 4.5 times on surfaces of various polyethylene samples stretched from 5.2 to 5.3 times the original length. For one sample, adsorption increased 8 and 2.5 times, respectively, on the convex and concave surfaces of a bent strip. Autoradiographs of the strips taken after adsorption revealed the appearance of both homogeneous and heterogeneous adsorption on the stretched surface of the polyethylene. The electron micrographs of the strips showed that many small fissures, about 1-5μ in length, formed on their surfaces after the strips were bent or stretched. Enhanced adsorption of the surface-active substance along these fissures was suggested. On the basis of these observations, it is proposed that in stretching or bending, fissures increase adsorption of the detergent, and the adsorption in turn promotes further development of fissures. Thus, bending and adsorption mutually promote the growth of fissures which finally result in failure of the polyethylene.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080410
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  • 3
    Electronic Resource
    Electronic Resource
    Rheo-optical studies of high polymers. XVII. Time-temperature superposition of time-dependent birefringence for high-density polyethylene (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1195-1209 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The strain-optical coefficient and relaxation modulus were simultaneously measured for high-density polyethylene at various temperatures ranging from 12 to 100°C. Not only horizontal but also vertical shifts were necessary to obtain smooth master curves by the application of time-temperature superposition. However, the relaxation modulus decreases with rising temperature while the strain-optical coefficient increases. This behavior indicates that the variation of the relaxation modulus and the strain-optical coefficient with time can not be explained by a decrease in crystallinity with rising temperature since a decrease in crystallinity usually causes a decrease in the strain-optical coefficient with time can not be explained by a decrease in crystallinity with rising temperature since a decrease in crystallinity usually causes a decrease in the strain-optical coefficient. It was emphasized that another explanation should be sought for the vertical shift in the time-temperature superposition of the time-dependence curves of the relaxation modulus and the strain-optical coefficient at various temperatures. The master curve of the strain-optical coefficient at various temperatures. The master curve of the strain-optical coefficient or the optical distribution function of relaxation times determined from it serve to distinguish the type and thermal history of the polyethylene.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080714
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  • 4
    Electronic Resource
    Electronic Resource
    Crazing of polystyrene containing two rubber balls: A model for ABS plastics (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 1085-1095 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to study the crazing behavior in rubber-toughened glassy polymers, polystyrene samples containing two rubber balls of the same diameter with varying separations have been prepared. They were subjected to simple tension, and their crazing behavior was observed. When the two balls are close together, the craze-initiation stress is considerably lower than that of single-ball samples. With increase in the distance between the two balls the craze-initiation stress increases at first almost linearly and levels off when l/d reaches about 1.45, where l and d are the center-to-center distance and the diameter of the balls, respectively. When l is sufficiently small, the crazes are seen to develop extensively at the inner surfaces of the balls and finally bridge with each other. The crazes bridged between the balls expand largely in the plane perpendicular to the applied load.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100610
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of methods for determining the refraction correction for light-scattering photometers (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 193-200 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recent 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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100201
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  • 6
    Electronic Resource
    Electronic Resource
    Generalization of the diffusion equation (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 569-570 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100313
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  • 7
    Electronic Resource
    Electronic Resource
    Rheo-optical studies of high polymers. XVIII. Significance of the vertical shift in the time-temperature superposition of rheo-optical and viscoelastic properties (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1211-1225 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To determine the true reason for the increase in birefringence and the decrease in relaxation modulus for high-density polyethylene with rising temperature, changes in crystalline structure as well as in thermal, viscoelastic, and rheo-optical properties with temperature were measured, by several techniques, including DSC, DLI, infrared dichroism, x-ray diffraction, and NMR. The values for degree of crystallinity obtained from the DSC fusion curve, density, and infrared absorbances coincide very well and show almost no divergence till about 80°C. The optical vertical shift factor pT can be related to the ratio of the orientation function for the crystal c axis at an arbitrary temperature to that at the references temperature, fε/fε0. The mechanical vertical shift factor bT, on the other hand, is associated with the temperature dependence of the mobile fraction, as determined by NMR measurements, but not with variations in degree of crystallinity.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080715
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal analysis of polysiloxanes. II. Thermal vacuum degradation of polysiloxanes with different substituents on silicon and in the main siloxane chain (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1823-1830 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermogravimetric (TG) investigations of various substituted polysiloxanes of the type \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm R}_1 {\rm R}_2 {\rm SiO\rlap{--} )}_n $\end{document} have been carried out in vacuo and the activation energies for the depolymerization processes calculated from the resulting thermograms. (R1 and R2 are methyl, ethyl, n-propyl, trifluoropropyl, or phenyl.) It is postulated that the activation energy is mainly a function of the inductive effect of the substituent group and that electron-withdrawing groups attached to silicon increase the activation energy, whereas electron-donating groups decrease it. A linear relation is found between the Taft constant σ* for the substituent on silicon and the calculated activation energy for depolymerization. Product analysis results from isothermal degradations indicate that the degradation mechanism in a silmethylene siloxane polymer and a silethylene-siloxane polymer is very similar to that in polydimethylsiloxanes (PDMS). For the \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm R}_1 {\rm R}_2 {\rm SiO\rlap{--} )}_n $\end{document} polymers, the amount of cyclotrisiloxane in the degradation products increases with the size of the substituent on silicon, and it is postulated that the rate of depolymerization is mainly influenced by short-range steric interactions between the substituents on the silicon atoms of the siloxane chain.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160081016
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  • 9
    Electronic Resource
    Electronic Resource
    Diffusion and reaction in polyester melts (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1671-1682 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An understanding of the physical and chemical processes involved in the melt polymerization of polyesters in the higher inherent viscosity ranges is of fundamental importance in polyester preparation. For example, the volatile condensation product must diffuse to a polymer-vapor interface before polymerization can take place. Thus, the rate of polymerization of a polyester may be dependent not only upon the chemical kinetics of the polymerization reaction but also upon the diffusion of the condensation product through the polymer melt. The objective of the work presented in this paper was to determine to what degree diffusion or reaction kinetics, or both, limit the melt polycondensation of poly(ethylene terephthalate). Degrees of polymerization in melts between 0.0285 and 0.228 cm in depth at 270°C were measured for various reaction times and were compared with the predictions of mathematical models. The polycondensation rates under these conditions depend upon both the polycondensation rate constant k1 and the diffusivity D of ethylene glycol through the melt. Estimates of the values to these parameters are: k1 = 0.0500 (moles/mole of repeat unit)-1 sec-1; D = 1.66 × 10-4 cm2/sec.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.180110901
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  • 10
    Electronic Resource
    Electronic Resource
    Light-induced graft copolymerization of vinyl monomers to collagen by use of benzophenone as sensitizer (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 2953-2956 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170121221
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