Real-time monitoring of resin infiltration process in vacuum assisted molding(VARI) of composites with carbon nanotube buckypaper sensor

In this study, a flexible and highly sensitive carbon nanotube buckypaper(BP) sensor was fabricated and validated which can be embedded in the composite reinforcement to real-time monitor flowing and infiltration of the resin for vacuum assisted liquid composite molding(VARI). The BP sensors were prepared by the spray-vacuum filtration method with mono-dispersion of multi-wall carbon nanotubes. It turns out that the excellent properties of the BP sensors can be obviously characterized; for example, conductivity, sensitivity and permeability, which were confirmed through contrasting the penetration of acetone and resin to the BP sensor. The utility of this novel technology about BP sensor monitoring resin flow front had been demonstrated through penetration evaluation experiment. The change in resistance with time obtained by BP sensors described the advancement of resin flow front with time, and comparing with the information recorded by a camera and a stopwatch, the results were basically the same. Additionally, because the permeability is an important process parameter during infiltration, affecting manufacturing cycle and product quality, four different conditions for the number of layers about the laid glass-fiber-reinforced were investigated. The comparison results of different permeability were gained from the information collected by BP sensors in real-time monitoring and combined with Darcy's law. This paper not only reveals the ability of BP sensor as a new method in real-time monitoring, but also provides a new way to avoid defects and optimize production in VARI processes.