Correlation of dynamic dielectric measurements with viscosity in polymeric resin systems

Dynamic dielectric analysis has been used to study curing polymer systems and thermoplastics. Measurements have been made over a frequency range of six decades. This wide range of frequencies increases the amount of information which can be obtained. The data are analyzed in terms of the frequency dependence of the specific conductivity sigma and the relaxation time tau, parameters which are characteristic of the cure state of the material and independent of size of the sample. Dynamic dielectric measurements have been correlated with viscosity for the polysulfone thermoplastic UDEL-P1700 and with viscosity and ultrasonic measurements on the DGEBA-type epoxy Epon 828 cured with Agent U. The experimental results suggest that when ionic processes dominate the dielectric response, the intensive property sigma is a good monitor of the resin's viscosity. The results show that the dielectric relaxation time tau can be used to monitor the state of the system and the extent and rate of the reaction.