The use of a single-fibre fragmentation test to study environmental durability of interfaces/interphases between DGEBA/mPDA epoxy and glass fibre: the effect of moisture

Abstract The influence of environmental exposure, both thermal and hydrothermal, on the average critical length/diameter ( L c / D ) ratio of fibre fragments, as measured by the single-fibre fragmentation test, has been investigated. The increase in c / D for hydrothermally treated samples indicated that degradation of the interfacial properties was dominant, while L c / D for the thermally treated samples showed no change. Apparently, degradation of both the interfacial shear strength and the fibres occurred under hydrothermal conditions. Analysis of the distilled water in which the hydrothermally treated samples had been soaked detected the presence of ions from E-glass. Furthermore, fragmentation of the fibre after hydrothermal treatment reached its limit (saturation) at a lower value of applied strain than did fibres after exposure to the dry or thermal environments. Changes in strength at the interface and in the fibre appear to be the major factors influencing the L c / D values on hydrothermal exposure.