THE USE OF A SINGLE-FIBER FRAGMENTATION TEST TO STUDY ENVIRONMENTAL DURABILITY OF INTERFACES INTERPHASES BETWEEN DGEBA MPDA EPOXY AND GLASS-FIBER - THE EFFECT OF MOISTURE

The influence of environmental exposure, both thermal and hydrothermal , on the average critical length/diameter (L(c)/D) ratio of fibre frag ments, as measured by the single-fibre fragmentation test, has been in vestigated. The increase in L(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. Appa rently, degradation of both the interfacial shear strength and the fib res occurred under hydrothermal conditions. Analysis of the distilled water in which the hydrothermally treated samples had been soaked dete cted 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 t he dry or thermal environments. Changes in strength at the interface a nd in the fibre appear to be the major factors influencing the L(c)/D values on hydrothermal exposure.