Based on the well-established theory which has been proven also in practice that the resistivity of a resin is directly related to its viscosity, the rising of the Glass Transition temperature (Tg) can be estimated online using the measurements from resistance and temperature. Following this, Synthesites developed a proprietary software, namely the Online Resin State (ORS) module that is capable to provide accurately the Tg online and with DSC accuracy as can be seen in the table below. The ORS module has been developed for a range of thermoset resins. The ORS module was initially developed for isothermal cases and was further extended to deal with highly non-isothermal conditions i.e. high exotherms with long cooling stages. The ORS software can run independently for each cure sensor while the online estimated Tg can be used for quality control purposes as well as for actively controlling the curing stage of the whole blade. Finally a signal can be automatically transferred to the temperature control unit to stop heating and potentially to cool down. In this way, a considerable speed-up of the curing cycle can be achieved when a specific and fully reproducible Tg level has been achieved independently of the external conditions.
This is a feature that only Synthesites has demonstrated worldwide, makes this cure monitoring technology unique as composite manufacturers can rely on the online Tg estimation to stop heating well before the standard curing time saving time and energy but ensuring the (minimum) Tg of the structure.