Hygrothermal effects on the material properties and behavior of thermoplastic polyimide composites

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:237757

VanLandingham, M R; Eduljee, R F; Gillespie, Jr, J W ^[1]

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1. Univ. of Delaware, Newark, DE (United States). Center for Composite Materials

Thermoplastic polyimides are a relatively new class of polymers that exhibit high-temperature stability and are useful in composite applications. One such material is DuPont`s Avimid{reg_sign} K3B reinforced with Hercules` Magnamite{reg_sign} IM7 graphite fibers. This composite system exhibits excellent strength and toughness, as well as excellent retention of strength and toughness, after prolonged exposure to elevated temperatures. IM7/K3B also resists microcracking at extremely low (liquid nitrogen) temperatures. Further characterization of IM7/K3B thermoplastic composites is focused on evaluating hygrothermal effects on the material properties and behavior. Specifically, the dependencies of T{sub g}, G{sub Ic}, and microcrack resistance on the conditioning time, temperature, and humidity level are being explored. Observations and conclusions from these studies include (1) a reduction in glass transition temperature, T{sub g}, with moisture absorption that is recovered when the sample is redried, (2) development of microcracks in cross-ply and quasi-isotropic laminates conditioned for extended periods in steady-state hygrothermal environments, (3) indications of localized degradation of the material from studies using scanning electron microscopy and ultrasonic scanning on moisture-saturated laminates, and (4) non-Fickian anomalies in the moisture diffusion data that are related to the damage development.

• OSTI ID: 237757
• Report Number(s): CONF-9510177--; ISBN 1-56676-376-2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBON FIBERS
COMPOSITE MATERIALS
DAMAGE
DIFFUSION
EXPERIMENTAL DATA
FICK LAWS
FRACTURE PROPERTIES
FRACTURES
HUMIDITY
HYDRATION
IMIDES
LAYERS
ORGANIC POLYMERS
SCANNING ELECTRON MICROSCOPY
TEMPERATURE DEPENDENCE
TRANSITION TEMPERATURE
ULTRASONIC TESTING
WEIGHT MEASUREMENT