Temperature dependence of hydrothermal ageing of CSM-laminate during water immersion

Random glass fibre reinforced polyester resin specimens were exposed to hot water at different temperatures. Effects of the environmental history on strength characteristics of the composite were investigated using the three-point bend tests. The study shows that reduction of the strength of random-fibre composites due to hydrothermal effects is a rate process for which the temperature influences only the rate constant. The rate constant follows the Arrhenius equation 1/τ = 1/τ 0 exp [−E/RT], where 1/τ is the rate constant, E and R are activation energy and gas constant respectively; τ 0 is a constant and T is absolute temperature. The time/temperature superposition principle is applicable for the degradation process and a master curve for strength can be obtained by shifting the data along the logarithmic time scale by a shift distance, ln a D. This allows the estimation of strength at any temperture from experiments conducted only at one temperature.