Application of Printed Paper Sensors in Characterizing Curing Behavior of Thermosetting Resin Systems Using Dielectric Spectroscopy

This research article discusses the practical application of dielectric spectroscopy (dielectric analysis) in characterizing the curing behavior of a thermosetting resin system, i.e., melamine formaldehyde resin- impregnated paper. The insights of curing behavior help composite panel manufacturers find an optimum pressing time to achieve a trade-off between the composite panel's performance and the production cost. Real-time cure monitoring techniques, such as dielectric analysis (DEA), have been developed to overcome the limitations of trial- and-error methods, which have been in use for a long time for the same purpose. DEA measures changes in the dielectric properties of the material during the cross-linking reactions in resin and provides necessary information for the cure state of the material. In this study, paper sensors based on interdigitated electrodes were employed to measure the curing behavior of melamine formaldehyde (MF) resin-impregnated paper at isothermal conditions in the hot press. Moreover, the performance comparison of paper sensors was also done with commercial sensors. The paper sensors were found to be worked the same in performance, being better in terms of compatibility, thinness, biodegradability, low cost, flexibility, and non-heterogeneity. This study includes curing time measurement for MF resin- impregnated paper in isothermal conditions. Moreover, this study includes an analysis of the effect of temperature and pressure on the curing time of MF resin-impregnated paper. It was analyzed that curing temperature plays an important role in optimizing curing time as higher temperature leads to lower curing time, but applied pressure does not affect the curing time of the resin.