Onto the internal strain self-sensing properties of single walled carbon nanotube-reinforced epoxies

Non destructive, real-time monitoring of the stress/strain state of polymer composites can be achieved through a “nanomodification” of the matrix. Due to their high Raman scattering, electrical conductivity and implicit sensitivity to pressure and temperature, single-walled carbon nanotubes (SWCNT) are ideal elements to fulfil this task. In this work, SWCNT at a loading fraction as low as 0.1 wt% were homogeneously dispersed in a hot-curing epoxy matrix via a three-roll-mill process. Evolution of internal strains resulting alone from the manufacturing process was characterised by in situ monitoring of the Raman shifts during the different stages of the curing cycle. The G’-band shift and change in electrical resistance of the cured material was further analyzed under mechanical strain to estimate the magnitude of the internal stress field as well as the reinforcing effect of the SWCNT itself.