Novel non-destructive evaluation technique for the detection of poor dispersion of carbon nanotubes in nanocomposites

A wide use of advanced carbon nanotube polymer composites can be boosted by new non-destructive evaluation (NDE) techniques that can test the quality of the products to ensure that their specifications are met. It is well known in literature that the parameter that far more than others can affect the enhancing capabilities of the carbon nanotubes is their dispersion. Here we have presented a novel NDE technique based on infrared thermography able to evaluate the dispersion of the added nanoparticles in polymer nanocomposites. The NDE technique was used to compare pairs of samples whose difference is represented only by the level of dispersion. It was found a significant difference in the thermal response to heat transfer transients. Thus, the thermal response of a nanocomposite allows one to identify consistently good levels of dispersion with respect to lower levels of dispersion. A reference product, which has the expected dispersion level and achieves the desired design performance, can be used to test the thermal behaviour of other products coming out of the production process and those with poor dispersion can be identified. The physical phenomena that can explain the effects of multi-walled carbon nanotubes (MWCNTs) dispersion on the thermal response of the nanocomposites to the heat transfer transients were also identified.