Characterization of Thermosetting Epoxy Systems Using a Torsional Pendulum.

摘要

An automated torsional pendulum has been used to investigate epoxy systems with respect to the effects of cure, transitions, morphology and active environments (water vapor and organic liquid). The findings include: (1) the thermosetting process is characterized by two transition temperatures (T sub gg and T sub g infinity), (2) thermomechanical and optical data correlate through a phase inversion in a rubber-modified system, (3) gelation time can be used to control development of morphology, (4) a reversible low temperature transition (T(H2O ca.) - 70 C (1.6 Hz)) is induced by exposure to water vapor, (5) the glass transition temperature is lowered in the presence of water vapor, and (6) thermomechanical spectra of partially plasticized specimens display the transitions of two phases (unplasticized and plasticized) superimposed. (Author)