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  • Polymer and Materials Science  (25)
  • 1970-1974  (24)
  • 1955-1959  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Disulfide interchange in polysulfide polymersPaper presented at the Sixth Canadian High Polymer Forum at Ridley College, St. Catherines, Ontario, on April 14-15, 1955. (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 19 (1956), S. 17-27 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been made on the effect of thiols and disulfides on lowering the molecular weight of polysulfide polymers. It was shown that in the presence of aqueous sodium disulfide there is an interchange of chain segments. This effect is observable if a simple organic disulfide is present in the system, resulting in a lower molecular weight. Co-polymers can be prepared by heating together in the presence of sodium disulfide, aqueous dispersions of two different polysulfide polymers. When thiols are present in the system, interchange of disulfide groups occurs in the absence of sodium disulfide. The results show that disulfide/disulfide redistribution and thiol/disulfide interchange take place in polysulfide polymers. The occurrence of these same reactions has recently been recognized by workers in the biochemical field. A literature survey of thiol/disulfide reactions showed that results formerly attributed to oxidation/reduction reactions could be also explained by an interchange mechanism.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120199102
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular complexes of sulfur dioxide with organic carbonates (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 2601-2613 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectroscopic studies made on the bisphenol A polycarbonate-sulfur dioxide system showed evidence of interaction between polymer and penetrant. Equilibrium studies made on solutions of sulfur dioxide and organic carbonates chosen as monomer analogs showed that complexes of the donor-acceptor type were formed, and that at temperatures of 15°C and less the stoichiometry of these was greater than 1:1. The procedures described are compared with those used in other donor-acceptor studies, and the results observed from the equilibrium studies are interpreted by using data reported for other sulfur dioxide-donor systems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170111014
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid assessment of weathering stability from exposure of polymer films. III. Relative weathering stability of ABS and arylon, a related polymer blend (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1181-1185 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Arylon, a blend of an aromatic polysulfone and a terpolymer of acrylonitrile-butadiene and α-methylstyrene, weathers similarly to ABS. However its first-order rate constant for the loss of unsaturation is only 0.39 cm2(Wh)-1 as against 0.80cm 2(Wh)-1 for ABS. This slower weathering is probably caused by the decrease in light intensity penetrating Arylon compared with ABS as a result of the high degree of light scattering observed in the former.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180416
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  • 4
    Electronic Resource
    Electronic Resource
    Rapid assessment of weathering stability from exposure of polymer films. I. Real and simulated weathering of commercial ABS terpolymers (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1159-1171 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Changes in the infared transmission spectra of thin films were used to follow the natural and artificial weathering of ABS terpolymers. Photo-oxidation of the polybutadiene moiety, which is the major process involved, occurs only after a well-defined amount of ultraviolet energy has been absorbed. Therafter, unsaturation decreases in a first-order manner with respect to UV energy absorbed. Under artificial conditions with constant UV intensity, energy absorbed is synonymous with time, but this is not so in natural exposure because of the variability of solar energy and its UV content. The method permits rapid comparison of commercial grades of ABS with the advantage of using natural conditions. It has been shown that pigmentation (3.6 phr brown and 1.25 phr carbon black) increases weathering stability two- and fourfold respectively, as assessed by induction energy and rate of disappearance of unsaturation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180414
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  • 5
    Electronic Resource
    Electronic Resource
    Rapid assessment of weathering stability from exposure of polymer films. II. The effectiveness of different regions of the solar spectrum in degrading an ABS terpolymer (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1173-1179 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A simple and rapid method has been developed to determine the relative effectiveness of the different regions of the solar spectrum in weathering a polymer. The method is based on measuring the rate of degradation of the polymer in film form, exposed outdoors under a range of materials which transmit different amounts of solar UV. The stability of an unpigmented ABS terpolymer has been examined using this method. It has been shown that the relatively small amount of solar radiation in the range of 295-340 nm accounts for 41% of the total degradation process. Longer wavelengths are shown to be progressively less effective; wavelengths greater than 450 nm (which account for nearly 90% of the total energy of the solar spectrum) contribute less than 5% to the degradation process.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180415
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  • 6
    Electronic Resource
    Electronic Resource
    A cooperative molecular weight distribution test (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 269-282 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The development of gel permeation chromatography (GPC) has provided a convenient tool for the rapid determination of molecular weight distribution. The question has arisen as to the suitability of the method for specification purposes. The present work, suggested by the Naval Air Systems Command, represents an attempt to assess the precision of the method through a series of tests carried out by a number of laboratories using identical procedures on the same samples. Ten laboratories agreed to take part. Naval Ordnance Station, Indian Head, worked out standard conditions for operation of the chromatograph, for calibration of the columns, and for analysis of the GPC curves. Two samples of polystyrene were used by the various organizations for calibration of their instruments. Number-average molecular weight, heterogeneity index, and cumulative molecular weight distribution curves were determined on four samples of carboxyl-terminated polybutadiene (CTPB) and two samples of hydroxyl-terminated polybutadiene (HTPB), all unidentified except by letter code. All laboratories used identical directions for setting up CTPB and HTPB calibration curves which were based on curves determined from vapor-pressure osmometer molecular weights and GPC count numbers of fractionated material. Variation among the different laboratories was 0.15 in heterogeneity index, and a maximum of 1200 in molecular weight provided one aberrant set of values was eliminated. The six samples had heterogeneity indices from 1.15 to 1.54, while molecular weight varied from approximately 3000 to 6000. The average coefficient of variation of the molecular weight values was 6.2 ± 0.7%, which is quite acceptable. Variation in heterogeneity index was too great for specification purposes when considered among the different laboratories, but may be sufficiently good when measured by any one laboratory.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170121
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Free-radical decay in irradiated PMMA (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 75-80 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Data from the literature are analyzed to show that decay of the chain-end radical of PMMA in the regime of 80-130°C and 1-13000 atm occurs by two mechanisms operating in parallel. These processes are characterized by activation volumes of ca. 70 Å3 (I) and ca. ∼7.5 Å3 (II), suggesting that decay by process I occurs by chain-end diffusion and decay by process II occurs by unzipping of the polymer radical to the monomer.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.180120106
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  • 9
    Electronic Resource
    Electronic Resource
    Relevance of cage recombination in the plastic deformation of polymers (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 2441-2451 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For a polymer in which permanent rupture of individual molecules is the rate-limiting process for plastic deformation, the kinetics of chain-end diffusion and secondary radical reactions should be compared with the kinetics of caged radical recombination in the calculation of activation parameters for plastic deformation. If mechanisms of cage escape are slower than those for cage recombination, the activation parameters for plastic deformation will differ from those for the initial bond-breaking process. For the case of polyethylene deformed in the vicinity of 250°K, the critical thermally activated event appears to involve scission of the polymer molecule near the site of an abstracted hydrogen atom. For this system the dominant cage-escape mechanism is diffusion, which is faster than either hydrogen abstraction or unzipping to the monomer. However, at low stresses the rate of cage recombination is expected to be higher than the rate of cage escape, so that the activation parameters for deformation should be the sum of those for chain scission and diffusion. The contribution of diffusion (ca. 15 kcal/mole) to the activation energy for deformation (E*, extrapolated to zero stress conditions) is relatively modest. However, the calculated molar activation volume for deformation V* increases by almost an order of magnitude, i.e., from ca. 10 to ca. 76 cm3/mole when diffusion is required. Consideration of experimental values of E* and V* for high molecular weight polyethylene indicates that, in the regime examined, chain scission plus chain-end diffusion is required to effect plastic deformation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.180111212
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  • 10
    Electronic Resource
    Electronic Resource
    Rigidity of polycarbonate in the presence of sulfur dioxide (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 10 (1972), S. 2325-2331 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A torsional pendulum method was used to study the transient effects of sulfur dioxide at pressures up to 700 torr on the rigidity of Bisphenol-A polycarbonate at 25°C. Incremental increases in pressure led to a decrease and then to an increase in rigidity. Removal of sulfur dioxide at the rigidity minimum led to a rapid recovery in rigidity, but after apparent equilibrium had been reached the rigidity was not fully reversible. These observations provide evidence that sorption of sulfur dioxide results in structural reorganization of the polymer. A qualitative discussion of the data is presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.180101202
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