LONG-TERM DURABILITY OF POLYMER COMPOSITES

摘要

Creep and creep-rupture of uni-directional composite laminates were characterized and modelled. Individual and interactive influence of stress, temperature, moisture, and physical aging on creep and creep-rupture of a polymer composite (Hexcel F263 epoxy reinforced with 54% by volume of Toray T300 carbon fibers) were studied. The composite exhibited linear creep at constant stresses < 7 MPa in the temperature range 295 - 503K. Moisture accelerated creep through plasticization (i.e. lower the Glass Transition Temperature, T_g) of the epoxy matrix and moisture-induced creep acceleration was found to be equal to creep acceleration in a dry sample by equivalent temperature increase. Moisture accelerated creep-rupture. Physical aging retarded creep and accelerated creep-rupture. In addition to reducing the moisture diffusivity and saturation moisture, physical aging caused a reduction in the magnitude of creep and creep-rupture acceleration by moisture when compared to non-aged material at the same moisture level. Similar interactive influence was observed at various stress and / or temperature levels. The data have been appropriately modelled and are currently being used in the modelling of creep and creep rupture of multi-directional laminates. The results of the modelling will be presented and discussed at the time of presentation.