The effect of pressure and temperature on time‐dependent changes in graphite/epoxy composites below the glass transition
作者:
Jovan Mijović,
R. C. Liang,
期刊:
Polymer Engineering&Science
(WILEY Available online 1984)
卷期:
Volume 24,
issue 1
页码: 57-66
ISSN:0032-3888
年代: 1984
DOI:10.1002/pen.760240107
出版商: Society of Plastics Engineers, Inc.
数据来源: WILEY
摘要:
AbstractEffects of pressure and temperature on time‐dependent changes in physical/mechanical properties of graphite/epoxy composites were investigated. Samples were cut from the eight‐ply‐thick laminates of commercially used composites, post‐cured, and then quenched to environments of various temperature and pressure. Time‐dependent changes in their properties were analyzed by thermal and thermomechanical (dynamic mechanical) measurements. An increase in the glass‐transition temperature was found to occur as a function of time. The rate of this process was enhanced by an increase in temperature and/or a decrease in pressure. An explanation was offered in terms of types and mechanisms of molecular events that occur in the glassy state. Time dependent decrease in free volume (and enthalpy) takes place but is not the sole mechanism responsible for the observed increase inTg. After a certain period of time (which depends onTandPof the environment), additional crosslinking appears to
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