Numéro
J. Phys. IV France
Volume 120, December 2004
Page(s) 191 - 199
DOI http://dx.doi.org/10.1051/jp4:2004120022


J. Phys. IV France 120 (2004) 191-199

DOI: 10.1051/jp4:2004120022

Modelling of changes in physical and mechanical properties of structural materials during long-term exposures at elevated temperatures

J. Kohout

Department of Physics, Military Technology Faculty, Military Academy in Brno, Kounicova St. 65, 612 00 Brno, Czech Republic

Jan.Kohout@vabo.cz

Abstract
Long-term exposures of various industrial structural materials at sufficiently elevated temperatures cause substantial changes in materials structures and, consequently, substantial changes in their physical and materials properties. The paper is focused to the influence of thermodegradation of glass-fibre-reinforced polyamide 66 in dry air and gear oil on its mechanical properties. As the thermodegradation of polymer materials is diffusion controlled process, the paper starts with the description of water diffusion in tested material. Then a very simple degradation mechanism is proposed for modelling the main features of real degradation processes. Regression functions describing the changes in mechanical properties of polyamide details during exposure are verified by the fit of experimental results. In the end of the paper some general considerations about the changes in other structural materials during exposures are done and supported by some experimental results.



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