INFLUENCE OF AGING AND WETTING ON DYNAMIC-MECHANICAL PROPERTIES OF MULTIFUNCTIONAL EPOXY-RESINS FILLED WITH PITCH-BASED CARBON SHORT FIBERS

Pitch-based carbon and graphite short fibers (PCF and PGF) as function al filler materials were filled in multi-functional epoxy resin (EP) u sing five types of hardeners with 22.2 wt%. Influence of aging and wet ting on dynamic mechanical properties of these materials was measured by the use of the nonresonant forced vibration method. Aging of the sp ecimens were carried out at 130 degrees C for 5000 h and wetting was c arried out at 21 degrees C in distilled water for 5000 h. The longer t he aging time? the less the weight of the specimens which reached a ma ximum was 5.3 wt% after 5000 h. The glass transition temperature (T-g) for all the specimens increased. The storage moduli (El) for the aged specimens did not change much at low and room temperatures compared w ith those for the unaged specimens (UA) but they increased at high tem peratures. The maximum wetting rate of the specimens was 5.1 wt% and t he values of T-g decreased for all the specimens. The values of E' inc reased in the range from a low temperature (-140 degrees C) to a room temperature (25 degrees C) but they decreased at a high temperature (2 00 degrees C). This tendency was more significantly observed in specim ens cured with diamine hardeners than specimens cured with acid anhydr ous hardeners.