Influence of physical aging on the time-dependent properties of network epoxies and epoxy-matrix compositesThe matrix-dominated properties of a network epoxy and its carbon fiber-reinforced composite are noted to be affected by sub-glass transition temperature T(g) annealing in a nitrogen atmosphere. The damping behavior, stress relaxation rate, and enthalpic state of the matrix material were found to decrease as functions of sub-T(g) annealing time. This time-dependent change in physical properties is explained on the basis of a free-volume collapse which is related to the recovery process of the nonequilibrium glassy network of the epoxy. The physical aging in network epoxies has been demonstrated to be thermoreversible. Aging kinetics are studied by means of differential scanning calorimetry, stress relaxation tests, dynamic mechanical analysis, and thermomechanical analysis.
Document ID
19840046596
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Kong, E. S. W. (NASA Ames Research Center Materials Science and Applications Office, Moffett Field; Stanford University; Stanford Joint Instit, United States)