DIELECTRIC PARAMETERS TO MONITOR THE CROSSLINK OF EPOXY RESINS

摘要

Recent developments in dielectric monitoring of cure processes are considered. Direct current (dc) conductivity and dielectric data concerning the crosslinking of an epoxy resin are analyzed and compared with the results of late microwave experiments. The analysis of the dielectric behavior of the system carried out on a rather wide frequency interval ( 10(3)-10(10) Hz) has provided a deeper insight into the relationships between dielectric parameters (i.e., de conductivity, permittivity, relaxation time and shape parameters, and the physical and chemical modifications of the systems). The results confirm the possibility to utilize dielectric quantities to obtain information on relevant parameters such as conversion, viscosity change, sol-gel transition, glass transition temperature, and dynamics of cooperative relaxation phenomena of the system. The required dielectric data can be gathered by simple methods that facilitate in situ applications. (C) 1997 John Wiley & Sons, Inc. [References: 36]