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  • 1
    Electronic Resource
    Electronic Resource
    The design and application of a microfoil tensile test apparatus for monitoring the degree of ultraviolet degradation of polymers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1620-1623 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microfoil tensile test apparatus has been developed to determine the tensile strength of thin slices cut from the surface of uv-degraded plastic products. It will be shown that it is possible to obtain data on the degree and depth of ultraviolet degradation in polypropylene copolymer and high-density polyethylene with the microfoil tensile test apparatus and to relate this to the impact resistance. The results are in agreement with the results determined by infrared spectroscopy but are obtained in less time and more accurately. The influences of sample preparation and geometry, elapsed time after microtoming, and method of processing on the tensile strength, will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142441
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  • 2
    Electronic Resource
    Electronic Resource
    Natural Fibre Mat Thermoplastic Products from a Processor's Point of View (2000)
    Springer
    Applied composite materials 7 (2000), S. 415-420 
    Details
    ISSN: 1573-4897
    Keywords: composites ; automotive ; natural fibres ; processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Natural fibres have significant advantages over glass, as an alternative fibre reinforcement material. Natural fibres are more environmentally friendly, healthier and safer, and cause less abrasive wear of processing equipment. On the other hand, their mechanical properties show a large scatter, and are at best equivalent to glass (natural fibres, however, have a lower density). Further disadvantages of the current natural fibre reinforced materials are their moisture sensitivity – which makes them prone to swelling and rotting – their smell and their current cost level. Experiments with the application of Natural Fibre Mat Thermoplastics (NMT) on current automotive products proved the disadvantages. On the other hand it yielded several new research themes concerning property limits and gave insight in the area's where to optimize in order to get a broad application of natural fibre reinforced plastic products. Looking towards the long term, other alternatives, like bio-composites or all-PP composites should be further explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026554610834
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Role of oxygen diffusion in polymer ageing: kinetic and mechanical aspects (1994)
    Springer
    Journal of materials science 29 (1994), S. 569-583 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract For an ageing process involving the consumption of a small molecule (typically O2 or H2O) by reaction with the polymer, there are critical conditions of reaction rate and/or thickness above which the process becomes kinetically controlled by the diffusion of the small molecule in the polymer. Suitable lifetime prediction models must then involve the thickness distribution of reaction products. This latter can be predicted from Fick's law, modified by a term relative to the rate of consumption of the diffusing species by the chemical reaction. Some problems related to the use of this approach are examined here. It appears that, in the most frequent case, the thickness of the degraded layer is of the order of magnitude of D/k, where D is the diffusion coefficient and k the pseudo-first-order rate constant for reactant consumption. Some examples of application related to photochemical, radiochemical and thermochemical ageing are examined. It can, for instance, be shown that in photochemical or radiochemical ageing, the thickness of the oxidized layer (TOL) is proportional to the reciprocal of l β, where l is the radiation intensity and Β an exponent depending essentially on the radical chain mechanism. It is generally expected that in the case of thermal ageing, the TOL is a decreasing function of the temperature. Some consequences of diffusion control on accelerated and natural ageing methods are briefly examined. The consequences of the ageing-induced “skin-core” structure due to the diffusion control are examined. The main features of the observed polymer embrittlement can be explained in terms of fracture mechanics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445968
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    Paper (German National Licenses)
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