Microstructure and thermophysical properties of polymer nanocomposites based on polylactic acid and carbon nanotubes

Using the methods of optical microscopy and differential scanning calorimetry, the microstructure and thermophysical properties of polymer nanocomposite systems based on polylactic acid and carbon nanotubes were investigated. From the data of optical microscopy, it was found that at a content of 0.5% of nanotubes in the system, a percolation transition is observed, in which clusters of nanotubes permeate the entire volume of the material. On the basis of calorimetric studies, it is shown that the temperatures of melting, cold crystallization and glass transition, as well as the degree of crystallinity and heat capacity jump during glass transition acquire minimum values with a filler content equal to 0.5%. It is the surface of the nanotubes that has a decisive influence on the thermophysical characteristics of the studied nanocomposites. The maximally developed surface of the filler, which occurs during the formation of a percolation cluster, complicates the processes of movement of macromolecules and prevents their formation of crystal structures.