Wireless chipless cure monitoring sensor for fibre-reinforced plastics

In this work, a novel fully passive chipless wireless cure monitoring sensor for fibre-reinforced plastics (FRP) structures is presented. The sensor is the first system that enables locally wireless monitoring of the rising cross-linking level of the polymer molecules and the reaction temperature of epoxy resins during the exothermic curing reaction at particular critical locations inside FRP structures. The temperature and permittivity of the reacting epoxy resin composition is determined by measuring and evaluating the change in resonance frequency for two substrate integrated waveguide (SIW) resonators. The measurement results obtained show an excellent accordance with the data provided by the widely used, and established, cure monitoring technique, differential scanning colorimetry (DSC).