Monitoring the change of viscosity during cure reaction of epoxy resins with resin position sensor

It was required that the fundamental understanding of the resin's rheological properties, such as viscosity, gel point and degree of cure are known during the processing of epoxy resin. In order to monitor these properties in-situ, a sensor system that can measure the viscosity changes during cure is needed. The resin position sensor (RPS) based on DC conductometry has been able to measure the ionic contents and electrical conductivity of most organic resins. Complex viscosity and electrical resistance were measured simultaneously during the cure of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin with polyamide by mounting the RPS on the upper plate of rotational rheometer. To correlate the viscosity with the resistance, the rheological model for the viscosity changes and the electrical model for the resistance changes were used. From the results, the interrelationship of viscosity and resistance of epoxy resin could be confirmed.