2000 Volume 12 Issue 3 Pages 291-297
This paper reports on a comparative study carried out for different type of sensors which are able to monitor in-situ curing of thermosets resin. In fact, the thermoset matrix composites are increasingly used as structural parts in complex technological structures. So, monitoring the matrix microstructural evolution and the development of internal stresses during the cure is now of the utmost importance. Taking in account their inhomogeneous structures and processing methods, mesoscopic sized sensors may be embedded into the composite materials. Until now different characterisation techniques have been applied independently in order to monitor essentially the cure process:
-Frequency dependant dielectric measurements provide a sensitive in situ sensor able to give access to the electrical conductivity and complex permitivity of the surrounding medium. The conductivity parameter related to the ionic mobility is linked to the polymerisation advancement
-The ultrasonic waves are generally used for global characterisation of mechanical properties. For in situ applications, a piezoelectric element is embedded in the structure during its processing and the rheological properties of such a material-system can be monitored.
-Refractive index measurement is carried out with a fibre-optic sensor. This optical parameter allows to determine the density of the thermoset resin during the cure process and to access to the extent of cure.
The multidetection measurement seems to be a powerful tool to understand the chemorheological mechanisms occurring during the thermosets resin cure process.
