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  • 1
    Electronic Resource
    Electronic Resource
    Molecular fracture in natural rubber during tensile testing at low temperaturesPaper presented at the Symposium on Mechano-Chemistry of Polymers, American Chemical Society National Meeting, Washington, D.C., September 16, 1971. (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 585-598 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sulfur-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.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100402
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  • 2
    Electronic Resource
    Electronic Resource
    Free radical formation in oriented polybutadiene during mechanical deformation below Tg (1974)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 22-27 
    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: The tensile behavior of oriented polybutadiene at 83°K is systematically studied as a function of strain rate and pre-test orientation. Electron spin resonance studies of radical formation are made in conjunction with the mechanical tests. Three different modes of mechanical behavior are observed (brittle, crazing and a second ductile behavior without crazing), depending on test conditions. Radical formation is observed in association with the two ductile modes of behavior. The ESR spectra obtained are attributed to a combination of allyl radicals formed by chain scission between the α-methylene groups and peroxy radicals. The relative quantity of the two radical species present is thought to be related to the ratio of cis/trans-isomerism. Stability of the radicals observed with time and with an increase in temperature is studied. Further studies are made of the quantity of environmental test gases absorbed during crazing.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760140105
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  • 3
    Electronic Resource
    Electronic Resource
    Impact failure of poly(methyl methacrylate) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 2131-2137 
    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: Damage development during instrumented falling weight impact (IFWIM) testing of poly(methyl methacrylate) (PMMA) is recorded using short pulse photography. The first visible damage is cracking on application of the peak force. Finite element analysis predicts the deformation and state of stress throughout the specimen until the first point of failure is reached. A variation in the specimen geometry produces a significant change in initial failure energy, while the maximum tensile stress is approximately constant. The proposed failure criterion is the attainment of a critical time-dependent value of tensile stress. © 1992 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070461209
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  • 4
    Electronic Resource
    Electronic Resource
    Hydrogen evolution from natural rubber during tensile tests (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 5 (1967), S. 317-320 
    Details
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.110050408
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  • 5
    Electronic Resource
    Electronic Resource
    Impact damage in a composite materialPresented in part at the 8th Int. Conference Deformation, Yield and Fracture of Polymers, Cambridge, U.K. (1991). (1993)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 14 (1993), S. 286-291 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Damage development in plates of a glass fiber-reinforced polypropylene is recorded, using short pulse photography, during instrumented falling weight tests using the excess energy approach. It is seen that the damage is progressive throughout the test but its initiation cannot be detected either by freeze-frame photography or visual observation. Specimens are therefore subjected to low-energy impact followed by microscopic observation of the tensile face. It is found that the initial damage mechanism is cracking of the matrix at the fiber-matrix interface, the crack propagating along the fiber. The finite element method is used to estimate the stress distributions at damage initiation in 4-ply and 8-ply samples cut from unidirectional and cross-ply plaques. The computed results indicate that initial damage occurs when the transverse tensile stress reaches a critical value.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750140403
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