Real-time cure behaviour monitoring of polymer composites using a highly flexible and sensitive CNT buckypaper sensor

Abstract

In this study, we developed a buckypaper (BP) composed of a mono-dispersion of multi-walled carbon nanotubes (MWCNTs) via a spray-vacuum filtration method. This highly flexible and sensitive carbon nanotube buckypaper (MWNCTs-BP) sensor can be integrated into complex curved surfaces and at critical stress areas to monitor the dynamic manufacturing process of fibre-reinforced composites in real time. A dynamic heating cure cycle and two revised cure cycles were designed to study the response of the resistance of the buckypaper to resin phase changes during the composite manufacturing process. Dynamic mechanical analysis (DMA) was performed to obtain the cure behaviour of a glass fibre/epoxy composite as a baseline to compare with the MWCNTs-BP sensor output. The experimental results show that the cure behaviour of epoxy/glass composites can be effectively monitored by the relative resistance change of the BP sensor embedded in the composite laminate. The MWCNTs-BP shows that the lowest viscosity point and gelation point of the composite resin were at 78 °C and 125 °C during the dynamic heating cure cycle, which is consistent with the DMA results. The lowest viscosity and gelation point can also be accurately obtained during the revised cure cycles. The MWCNTs-BP system has great potential as a sensor to establish and optimize manufacturing processes and to improve the cure quality of fibre-based resin composites.