Characteristics of water in graphite/epoxy composites
- Michigan State Univ., East Lansing, MI (United States). Dept. of Materials Science and Mechanics
The effects of water on physical and chemical property modification were investigated for a graphite/epoxy (Gr/Ep) composite laminate. The laminate was consolidated using unidirectional T300/934 graphite/epoxy prepreg. Specimens were hydrothermally-conditioned by immersion in distilled water at 45, 60, 75 and 90 C for more than 9,000 hours. The composite was characterized by evaluating the specimen weight change due to water absorption, by hygrothermal induced expansion, and by water-induced change of the glass transition temperature (Tg). Optical and scanning electron microscopy were conducted to assess surface modification associated with cracking and mass loss. Water sorption in Gr/Ep material exhibited both Fickian and non-Fickian diffusion behavior. Diffusion data showed that the time for the onset of non-Fickian behavior was inversely related to the exposure temperature. Anomalous (non-Fickian) behavior in the composite resulted from chemical modification and physical damage to the epoxy resin. Cracks, voids, and surface peeling due to moisture sorption were clearly revealed by SEM and optical microscopy. Surface cracking and mass loss in the composite have been used to explain the consequences of water sorption behavior. Thermomechanical analysis (TMA), desorption and infrared (IR) results suggested that retained water in the composite can be characterized, (1) by water residing at crack tips, interfaces and void, (2) by water associated with weak hydrogen bonding in the resin, and (3) by water strongly bonded to hydrophilic groups in the resin.
- OSTI ID:
- 89904
- Report Number(s):
- CONF-9409291-; ISBN 1-56676-220-0; TRN: IM9536%%334
- Resource Relation:
- Conference: 9. technical conference of the American Society for Composites, Newark, DE (United States), 20-22 Sep 1994; Other Information: PBD: 1994; Related Information: Is Part Of Proceedings of the American Society for Composites: Ninth technical conference; PB: 1319 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Space radiation effects on graphite-epoxy composite materials. [Electrons at 5. 0 x 10/sup 7/ rads/hr]
Processing and characterization of thick laminated composites