Assessment of dispersion in carbon nanotube reinforced composites using differential scanning calorimetry

For assessing the state of dispersion, which plays an important role in improving the mechanical properties of carbon nanotube (CNT) reinforced composite material, the relationship between the state of particle distribution and the change in the cure kinetics was experimentally investigated by the use of differential scanning calorimetry. It was found that the addition of CNTs to epoxy resin reduced the total heat of reaction. This may be because CNTs act as obstacles to the cross-linking reaction. The decrease was found to depend on the CNT concentration as well as the state of dispersion. To obtain a correlation between the decrease in the total heat of reaction and the quantity of well-dispersed particles, the mass of aggregated particles was measured by dynamic light scattering. The results showed that there is a correlation between the concentration of well-dispersed CNTs and the total heat of reaction. Any departure from this correlation could be interpreted as poor dispersion and the magnitude of the difference may serve as an indicator of the overall state of dispersion.