Moisture-temperature equivalency in creep analysis of a heterogeneous-matrix carbon fibre/epoxy composite

The objective of this study was to investigate the creep sensitivity of a heterogeneous-matrix carbon fibre composite as related to time, temperature and moisture. An interlaminar-toughened composite (Toray T800H/3900-2) was used as a model system for creep analysis. Constant-loading tensile creep experiments were performed on [±45]_2s laminate specimens at several isothermal temperatures for two moisture levels: dry and wet (0.9% moisture content). Long-term predictions of creep of the toughened composite could be made using the analytical results from this study. The effect of absorbed moisture in the laminate on creep compliance was shown to be quantitatively equivalent to an increase in temperature, and the temperature-moisture equivalency was established with the aid of a polymer-diluent miscibility theory.