Abstract
The composite materials were made from three multi-functional epoxy resins (EP) cured with five hardeners and filled with aramid (Technora®) short fibers (AFP) by 2.44 wt%. Effects of aging (heat-treated) at 130°C for 5, 000 h and wetting at 21°C for 5, 000 h in distilled water on the dynamic mechanical properties were studied. The morphology of the fiber dispersion in AFP-filled specimens did not change during the aging. Weight of the aged specimens decreased for a prolonged aging time. The maximum decrease during the aging for 5, 000h was 3.5wt%. The glass transition temperature (Tg) of all the specimens shifted to higher temperature by the aging. The dynamic storage moduli (E') of most of aged specimens decreased at lower temperature (-140°C) and room temperature (25°C) compared with those of unaged specimens. At higher temperature (200°C), the moduli of specimens almost increased and in particularly those of the specimens cured with diamines increased significantly. Absorbed water of wet specimens reached a maximum value of 5.0wt%, and values of the specimens cured with diamines were larger than those of the specimens cured with acid anhydrides. The Tgof all the specimens shifted to lower temperature by the absorption of water. E' of many wet specimens increased in the range of lower temperature to room temperature, but E' of all the specimens at higher temperature extremely fell down.
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