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  • 1
    Electronic Resource
    Electronic Resource
    Effect of cross-links which occur during continuous chemical stress-relaxation (1988)
    s.l. : American Chemical Society
    Macromolecules 21 (1988), S. 442-446 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00180a027
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Polymer aging insights available from modulus profiling data (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 29-35 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 recently developed analytical technique, modulus profiling, conveniently allows the mechanical properties of elastomers to be mapped with spatial resclutions approaching 0.05 mm. Thus, spatial heterogeneities in modulus caused by processing and aging phenomena can be easily monitored. This paper describes some typical results from polymer aging studies, which Indicate the insights available from this technique. These include application of modulus profiling to understanding (1) mechanical property deterioration of Viton in an elevated temperature, gamma-radiation environment, (2) recent continuous stress-relaxation results, and (3) the role of ozone for non mechanically-stressed materials in high energy radiation environments.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760290107
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Use of a thermomechanical analyzer to estimate the tensile compliance for polymeric materialsThis work supported by the U.S. Energy Research and Development Administration. (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 1291-1302 
    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: Values of the tensile compliance D for polymers ranging from hard plastics to rubbers have been estimated using a commercial thermomechanical analyzer in a novel manner. By slight modification of the standard instrumentation together with careful attention to experimental procedure, sample geometry, and data analysis, the values of D obtained for a wide variety of materials are shown to correlate well with values of the tensile modulus E obtained using more conventional techniques. The method appears to be capable of quickly and easily estimating values of D-1 ranging from 10+6 to 5 × 109 pascals.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1978.070220511
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Physical and chemical stress relaxation of a fluoroelastomer (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 1597-1605 
    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: Stress relaxation measurements were made at various temperatures on V-747-7, a commercial high-temperature rubber formulation from the Parker Seal Company. The data were analyzed by separating the chemical and physical relaxation processes by a method described in an earlier publication. The chemical relaxation process was found to be Arrhenius with an activation energy of 35.7 kcal/mole. The results allow us to predict the relative useful lifetimes of this material up to approximately 320°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210615
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  • 5
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance relaxation time and self-diffusion coefficient measurements of water in frog ovarian eggs (Rana pipiens) (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 80 (1972), S. 155-158 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Self-diffusion coefficient measurements of water in untreated ovarian eggs of Rana pipiens using nuclear magnetic resonance indicate that cytoplasmic water has reduced translational mobility compared with pure water. Using a simple two-state model, we find that ∼67% is “relatively immobile.” Consideration of the nuclear magnetic resonance spin-lattice and spin-spin relaxation times indicates that the decreased mobility can largely be ascribed to hydration. Our value for the self-diffusion coefficient (6.8 × 10-6 cm2/sec) is lower than those reported by other investigators using isotopic water exchange techniques on frog eggs chemically treated to remove the membrane. However, the results reported here are in agreement with unpublished data on untreated frog eggs implying that chemical treatment has modified the cytoplasm in some manner.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040800117
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  • 6
    Electronic Resource
    Electronic Resource
    Combined environment aging effects: Radiation-thermal degradation of polyvinylchloride and polyethyleneThis work was supported by the United States Nuclear Regulatory Commission as a part of the Qualification Testing Evaluation (QTE) Program conducted by sandia National Laboratories under Interagency Agreement DOE 40-550-75, NRC FIN No-A-1051. (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 2041-2051 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Results are presented for a case of polymer aging in which powerful synergisms are found between radiation and temperature. This effect was observed with formulations of polyvinylchloride and polyethylene and occurred in simultaneous and Sequential radiation-thermal experiments. Dose rate dependencies, which appear to be mechanistically related to the synergism, were also found. The evidence indicates that these aging effects are mediated by a thermally induced breakdown of peroxides initially formed by the radiation. Similar effects could be important to material degradation in a variety of other types of combined-stress environment. A new technique, which uses PH3 treatment of intact polymer specimens to test for the importance of peroxide is the pathway that leads to changes in macroscopic tensile properties, is described.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.170190816
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  • 7
    Electronic Resource
    Electronic Resource
    A kinetic model for predicting oxidative degradation rates in combined radiation-thermal environments (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 2683-2707 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex degradation behavior of a poly(vinyl chloride) (PVC) cable jacketing material in combined radiation/temperature/air aging environments is experimentally separated into two dominant radiation dose-rate effect mechanisms. The first, operative at high dose rates, involves diffusion-limited oxidation, which leads to heterogeneously oxidized samples. The second, important at low dose rates, involves thermally-induced breakdown of intermediate peroxides. In the homogeneous degradation regime, a theoretical kinetic model is derived which, based on experimental evidence, assumes unimolecular termination kinetics and rate-determining, hydroperoxide-mediated branching reactions. Dependent upon the ratio of particular rate constants, the model predicts that dose-rate effects will either continue to increase or eventually disappear as the dose rate is lowered. Theoretical analysis of sequential (radiation followed by temperature exposures) aging experiments allows a time-temperature-dose rate shifting procedure to be developed. Using this procedure, higher temperature combined environment results can be shifted to a lower reference temperature, thereby extending the lower temperature results to lower (and experimentally inaccessible) dose rates. By applying this procedure to experimental PVC data, evidence in support of the theoretical model is obtained. In addition, model predictions are shown to agree with 12-year real-time aging results.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.170231011
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