SEDL / STP / STP696-EB / STP36037S

Moisture Diffusion Analysis of Microstructure Degradation in Graphite/Expoxy Composites

Leung, CL
Members of the technical staff and senior staff associate, Rockwell International Science Center, Thousand Oaks, Calif

Dynes, PJ
Members of the technical staff and senior staff associate, Rockwell International Science Center, Thousand Oaks, Calif

Kaelble, DH
Members of the technical staff and senior staff associate, Rockwell International Science Center, Thousand Oaks, Calif

Pages: 18    Published: Dec 1979

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Abstract

Directional diffusion coefficients, that is, D¹, D², and D³, for the principal axis i = 1, 2, 3 of a unidirectional fibrous composite were determined by moisture absorption measurements. It was shown that the initial moisture absorption of a cured dry composite is non-Fickian and may relate to microstructural relaxation of internal stresses.

Moisture effusion rates of the specimens were also evaluated. Absorption-desorption kinetics over several cycles showed that there exists a damage mechnism in the composite which enhances moisture uptake from the dry state but does not enhance moisture release from the water-equilibrated state.