SYMPOSIA PAPER Published: 01 January 1975

Kinetics of Environmental Degradation in Graphite-Epoxy Laminates


A detailed study of the kinetics of environmental degradation in graphite-epoxy composites show a close correlation between analytical predictions and experimentally observed changes in interlaminar shear and fracture energy response under high moisture exposure conditions. Unaged composite specimens exhibit high interlaminar shear strength λb ⩾ 850 kg/cm2 (12 000 psi) and relatively low fracture energy Wb/A ≅ 10 to 20 kg cm/cm2 (56 to 112 lb in./in.2). Exposure to 95 percent relative humidity or water immersion at 100°C (212°F) for times t ⩾ 200 h produces a 30 to 50 percent reduction in λb accompanied by a concurrent two to fivefold increase in Wb/A and acoustic energy absorption. These property changes are shown to be irreversible and directly related to cumulative moisture degradation of the fiber-matrix interfacial bond. The magnitudes of these property changes are consistent with surface energy analysis and micromechanics predictions.

Author Information

Kaelble, DH
Science Center, Rockwell International, Thousand Oaks, Calif.
Dynes, PJ
Science Center, Rockwell International, Thousand Oaks, Calif.
Crane, LW
Science Center, Rockwell International, Thousand Oaks, Calif.
Maus, L
Rockwell International, Tulsa, Okla.
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Developed by Committee: D30
Pages: 247–262
DOI: 10.1520/STP32312S
ISBN-EB: 978-0-8031-4660-0
ISBN-13: 978-0-8031-0309-2