SEDL / STP / STP658-EB / STP34857S

Some Anomalies Associated with Moisture Diffusion in Epoxy Matrix Composite Materials

Whitney, JM
Materials research engineer, Air Force Materials Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio

Browning, CE
Materials research engineer, Air Force Materials Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio

Pages: 18    Published: Jan 1978

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Abstract

Diffusion of moisture into graphite/epoxy composites was investigated and some anomalies observed. In particular, data are presented which indicate a departure from classical Fickian behavior. An apparent two-stage diffusion process is observed in both the neat epoxy resin and derived graphite/epoxy composites. Evidence is presented which suggests time-dependent matrix cracking as the mechanism associated with the two-stage diffusion process. Comparison of laminate diffusion data with unidirectional data suggests that the diffusion coefficient is stress dependent.